“But Twilight, you promised!”

“I know,” Twilight Sparkle said. She finished signing her name with a flourish, lifted her quill, and inspected the paper closely. She nodded, and levitated it to the top of the pile beside her. “And I have every intention of following through, Rainbow.”

Rainbow Dash snorted. She was lying on her back on the floor of the Friendship Palace’s formal office, her legs splayed in all four directions. Her wings twitched beneath her as she groaned. “But you’re not gonna come now.”

Twilight bit her lip as she floated down the next form. Beside her, a towering stack of unfiled paperwork groaned and swayed menacingly. By contrast, the pile of completed work looked pathetically small. “Look, I know I promised that we’d have a flying lesson soon. But I said soon. Not right this second.”

Dash’s wings twitched restlessly, flexing with an obvious desire to be used. “So then when?”

“Later,” Twilight said crisply. She scanned over the form, prodding her lips with her quill. Then, she dipped it into her inkpot and got to work making some notations down the side. “This evening, maybe. Or tomorrow.”

“Tomorrow?” Dash groaned. “That’s, like, forever away. And who knows if Princess Celestia won’t just show up on your doorstep after breakfast and dump another ton of work on your plate?”

“Then I’ll just have to work through it as best I can.” Twilight nibbled on the end of her quill, staring at the paper with a furrowed brow. Dash’s complaining was making it increasingly difficult to concentrate.

“C’mon.” Rainbow said. “Just an hour. Celestia wouldn’t even have to know. Just get out there, stretch your wings a bit, and fly.”

It was tempting. It really was. Twilight said as much. “But Celestia trusts me, Rainbow Dash,” she went on. “If I just took a random break, then I’d feel really guilty about it, whether she found out or not. And besides, can’t you just go flying on your own?”

Dash sat up, leaning her weight back on her hooves. “I could,” she said reluctantly. “But I really wanted to give you that lesson I promised you on thermals. And…”

And?

“...and I might have a new trick that I wanted to show you.”

There it was. Twilight gave her a look. “Right,” she said. A tired smile tugged at the corner of her mouth. “No ulterior motives whatsoever.”

Rainbow Dash grunted. “Come on, Twilight,” she moaned. “I’m bored. And you promised.”

“Rainbow,” Twilight said, carefully. She put down the form she’d been squinting at and rubbed her eyes. “Do you know what I’m doing?”

“Uh.” Dash crossed her hind legs and folded her wings. “Paperwork?”

Twilight sighed. “Technically, yes,” she said. “But this is very important work! These are patents and development forms for new magic spells. The Canterlot Academy is relying on me, as the Princess of Friendship (and, by auxiliary relationship, of Magic), to go through and approve these for public use. That means reviewing trials, analyzing focus group results, approving methodologies, signing off on grants and other funding - “

“So you need to sign a bunch of stuff for a bunch of stuffy, eggheaded unicorns.” Rainbow Dash waved a hoof and snorted. “Why not just sign off on the bunch? Why d’you have to read ‘em all?”

Twilight sighed again, heavily. She felt a vein tugging on the back of her neck. She’d already been at this for three hours, and she did not need Rainbow sassing her methods right now. “Because these are experimental spells,” she said, very slowly. “I’m responsible for ensuring that they’re used safely, Rainbow! That they’ve been developed properly.”

Rainbow scoffed. “They’re probably just a bunch of namby-pamby paperwork spells or something,” she said. “How dangerous could they possibly be?”

Twilight looked at her sharply. “They - “ She glanced back down at the title of the paper sitting innocently before her. Good sense warred with her ego for a few moments. She massaged her forehead for a bit and grit her teeth.

Ego won out.

“They’re not ‘paperwork’ spells,” Twilight said. “They are, in fact, quite a bit more complex and dangerous than that.”

“Oh?” Rainbow said. She raised an eyebrow. “Then what kind of spell are they, anyway?”

Twilight almost held her tongue. Almost. “They’re from the Equine Biology department of the Academy,” she said, only somewhat reluctantly. “Specifically from a researcher specializing in reproductive biology.”

Rainbow’s muzzle scrunched up thoughtfully. “What, like sex?” she said dubiously.

Twilight levitated the first page of the paper up to her face and read the title aloud. “On The Bestowal of Male Gametes and Reproductive Organs To X-Chromosomal Equines.”

She glanced over the top of the paper. Rainbow Dash was blinking cluelessly at her.

Twilight rolled her eyes. “It’s about a spell that can be used to give a mare a penis,” she said bluntly. “So yes, Rainbow - exactly like sex.”

Dash’s eyes lit up. “Give a mare - no way!” she blurted. “That’s crazy!”

“It is,” Twilight said. “Which is why I have to be extra careful in reviewing the safety checks applied to the developmental - “

“You should totally give it a try!”

Twilight blinked. Her train of thought derailed in an interest, diving off of a cliff and dying in the resulting inferno. “What,” she said flatly.

Dash had sprung to her hooves. Her wings were stretched out, her legs bouncing up and down a bit. She was grinning like a madpony. “C’mon!” she said. “It’d be totally awesome!”

“Rainbow Dash!” Twilight said, aghast. “I can’t just cast an experimental spell on myself, especially not without reviewing the necessary safeties and procedures first.”

“Not you, dumbass,” Rainbow said, rolling her eyes. “Me!”

Twilight nearly choked. “I - what? That would be the absolute pinnacle of irresponsibility!” She blushed. “And besides, given the subject matter… I hardly think it’d be appropriate.”

“Come on, Twi.” Dash smirked. “At least it’ll give me some way to entertain myself while waiting for you.”

A slew of rather...lewd images rushed into Twilight’s mind. She stumbled over her words, her thoughts spinning. “I - but - ack! Rainbow, no!”

Rainbow sighed. “Fine. How ‘bout this? Think of it as a test, right? You can make sure that the spell works the way it should by testing it out on me. Doesn’t it come with a counterspell or something?”

Twilight mentally flipped through the notes she’d skimmed through earlier. “Well...yes,” she said, reluctantly. “But that’s no excuse to - “

“Then we’re golden,” Dash said. “Just cast the spell, and if it turns me into a giant dick monster or something, you can just cast the counterspell and turn me back.” She snickered. “Or not. Actually, a giant dick monster sounds kinda hilarious.”

Twilight shook her head, hardly able to believe what she was hearing. “I really don’t know how comfortable I am with this, Rainbow.”

“C’mon,” Rainbow urged, egging her on.” It’ll be fine. And who better to test a new spell than one of the Elements of Harmony?” She flexed her foreleg, smirking. “The Princess of Friendship herself? And you can personally make sure that it’s absolutely, totally safe - “

“Okay, fine,” Twilight blurted. She was blushing like mad when she said. “I will...attempt to cast the spell. As long as it gets you off of my back.” Her eyes met Rainbow’s. “Is that clear?”

“Crystal, ma’am.” Rainbow snapped off a smart-looking salute.

“Okay,” Twilight said. She took a slow breath. “Just...stand still, okay? I need to make sure that I’ve got this down.”

Rainbow waited patiently as Twilight checked, double-checked, then triple-checked the instructions. Once she was sure she’d gotten it, Twilight pushed the scroll aside, stepped around her desk, and faced Rainbow Dash head-on. Squaring her shoulders, she closed her eyes and summoned up her magic, her horn beginning to glow. She felt for Rainbow’s aura through her magic, weaving the spell and searching for a place to link it to Dash. She felt it slide into place, sparks flaring around her horn - and then released the magic.

Dash actually recoiled a bit, as if zapped. “Whoa!” she said loudly. “That stings!”

“Sorry!” Twilight said. “Oh, my gosh, this was a terrible idea. I can’t believe I just - Rainbow I’m sorry - I should have never - “

But Rainbow wasn’t paying any attention to her. Instead, her eyes were fixated firmly on her crotch, where a fat bulge was protruding just above her vulva. Mesmerized, with her muzzle hanging open slightly in awe, she watched as a thick, throbbing horsecock pushed its way out of her body. It flopped heavily down over one of her thighs, the flare stretching past the edge of her leg. A trickle of milky-white liquid drooled from the tip, running down her leg onto the floor and staining her fur dark.

“Wow,” Rainbow breathed. She gave her new appendage a prod and shuddered with obvious pleasure when it twitched in response. “Wow.”

“Um.” Twilight caught herself staring as well, and quickly yanked her gaze up to Rainbow’s face. Still, she’d been ogling long enough to catch an eyeful of the pair of heavy, musky orbs that had plopped out to accompany her friend’s new organ. Each one could rival a cantaloupe for size, and the skin around them was stretched tight; Twilight tried to keep herself from imagining just how full they were. Swallowing, she fixated on Rainbow’s eyes—don’t look down, don’t make it weird, it’s just a spell—and cleared her throat. “Do you feel alright, Rainbow?”

“Alright?” Twilight’s gaze darted down just long enough to catch one of Rainbow’s hooves curving around the circumference of her plump orbs, her wrist caught between that swollen surface and her thick, veined cock. Blushing, she looked back up to see Rainbow looking at her bemusedly. “I feel awesome. This is—ooh—fantastic. And it feels so good...”

“I’m not so sure,” Twilight said worriedly. She tried to keep her tone cool and analytical as she glanced over Rainbow’s stallionhood, struggling to keep her thoughts strictly scientific. “That’s nowhere near the normal size for a stallion’s normal genitalia, Rainbow. And the spell didn’t mention anything about increased, um…” She searched for the word, found it, and flushed. “Pleasure.”

Rainbow bit her lip, stifling a moan as she gave her hearty horsecock a squeeze.  She’d already begun rubbing her hooves up and down her length, her soft fur brushing gently against her throbbing shaft. It seemed to loom in Twilight’s vision, steadily stiffening and rising up into the air. “And that’s a problem...why?”

“Because these spells are dangerous!” Twilight shot back. She frowned. “And...could you not do that, please?” She blushed, averting her gaze once again.

“Do what? This?” Rainbow knelt down and nuzzled the flare of her shaft. It was easily four inches across, each throb just left it fatter, the steady drool of precum growing larger with each passing second. “Mmff. It just feels so good.” When she pulled her head away, her muzzle was covered in pre; she crossed her eyes to stare at it, giggled, and licked it off.

“It’s a problem because you should not be...well, masturbating! Immediately after receiving such a modification, your body should be adjusting! Preserving energy! It shouldn’t react with...arousal!”

Rainbow stroked a hoof across her tip and gave it a lick. She shivered happily again. “Maybe this is just what stallions feel like all the time?”

“Impossible,” Twilight said. Her biology notes from eighth grade leapt to mind, took one look at Dash’s eighteen-inch (and growing!) horsecock, and leapt right back into the abyss. Most stallions were twelve inches at the most—even Big Mac was only fourteen! And those balls! Those plump, engorged nuts looked like they were all but churning with seed! The largest she’d ever heard of couldn’t have been half that size! Dash’s cock throbbed again, and Twilight swore she could see her testes swelling, filling up with even more cum with each new flare of arousal. She swallowed. “If that were the case, it’d be impossible to keep them from just, well, having sex all the time! This is not what’s supposed to happen!”

She caught Dash staring pointedly at her flank, and her cheeks burned. Tearing her eyes away from her cock—that massive, virile cock—Twilight turned back to her desk and picked up the report in a flicker of magic.

“It just doesn’t make sense,” she murmured, scanning the abstract for clues. “This was supposed to be a simple additive organ spell; there’s nothing in here about increased libido, or oversized biology, or—”

Her thought process was interrupted rather rudely by a long, low moan. Whirling on her hoof, Twilight caught a glimpse of Dash: her torso folded in on itself, her muzzle pressed down over her cock, her lips clamped tightly around her shaft as her tongue lapped hungrily at the cascade of precum drooling down the side.

“Rainbow Dash!” Twilight’s horn flickered, and she pulled Dash’s muzzle back up off of her cock. Rainbow’s lips came off with a wet-sounding pop!, and a milky-white film of pre stretched across her mouth. “This is not okay. I’ve half a mind to just cast that counterspell right now and be done with this—”

“C’mon, Twilight,” Rainbow said. “Don’t overreact.”

“Overreact?” Twilight said. “I gave you that thing thirty seconds ago and you’re already sucking yourself off? Rainbow, I don’t even think it’s stopped growing yet, and you’re just...just…”

“What?” Rainbow raised an eyebrow and licked her lips.

“...encouraging it!” Twilight burst out. She glared at Rainbow for a few moments, her chest heaving.

Rainbow just grinned back at her. “Don’t blame me, Twi,” she said. “This stuff tastes really good.” She dragged her hoof across the tip, scooping up a hefty smear of precum from her slit. She began licking it off eagerly as she cradled her nutsack in her other hoof, curling it around their wide, overfilled radii.

“That’s precum, Rainbow,” Twilight said. “And I really am concerned for you.” Her brows knitted together. Oh, Celestia, why was Rainbow’s stallionhood so distracting? And why was that masculine, heavy musk suddenly the only thing she could smell? She mentally forbade her own libido from reacting, and groaned internally when she felt a trickle of liquid fall down her thigh. No. This was not okay. She had to put her hoof down.

“This spell could be a real problem,” she went on. “It might be addictive, or worse! What if there’s a positive feedback loop, or an unseen mental component, or—”

But Rainbow Dash had already stopped listening, once again. Now, she’d almost managed to reach her medial ring with her muzzle, a fat, bulging ring of flesh easily five inches across. How did she even fit all of that in there. And the scent...oh, Celestia, that was a real stallion’s musk, strong and pervasive and sexual. Rainbow didn’t even to take note of her own scent, though, too preoccupied with slurping loudly at her own cock to take notice of any part of the outside world. Her head bobbed up and down the first half of her dick, her stomach sucking in to let her get her muzzle as far down as possible. Every time she pulled back up, her lips left a sheen of saliva and pre mixing on the sides of her shaft.

Twilight was helpless to do anything but watch, mesmerized by the rhythmic bobbing of Dash’s head up and down her length. Before long, Dash grunted, her cock flexing. She swallowed the entire medial ring, her muzzle widening around it as she gulped down as much as she could manage. Her belly retracted toward her crotch, and her entire core flexed—and then she came. Twilight couldn’t even see the product of her orgam, so tightly was Rainbow’s mouth wrapped around her dick. But she could hear the loud splatter of cum against Dash’s throat, could hear the steady gulp, gulp of seed as Dash swallowed it all down. By the time she was finished, her mouth was streaming with trails of white, and her belly had a noticeable roundness to it.

Twilight’s logical mind reasserted itself. “Darn it, Rainbow!” she said. “This is serious!”

Rainbow’s lips popped off once again, this time with a wetter, dirtier-sounding schlick. Twilight’s legs nearly crossed at the very sound of it. “I know,” she said, her muzzle dripping with pre. “Seriously good. Seriously, Twilight, you have to taste this! My new dick is delicious!”

“That is a terrible idea,” Twilight shot back. She was mostly succeeding with keeping her eyes off of Rainbow’s shaft, an achievement that she congratulated herself... at least until she realized that the mammoth stallionhood was now brushing against the bottom of Rainbow’s chin. Another throb of that massive flare brought a good tablespoon of pre burbling up, a gob of the stuff sticking to Dash’s fur and hanging down in thin, milky strands. If she hadn’t been so concerned, the sight would have almost been comical.

“I am not going to...taste your new equipment,” Twilight said, rather lamely. Rainbow just cocked her head and smirked. She didn’t even need to stroke her shaft anymore; instead, simply moving her head from side to side was enough to tease her fat head further, leaving more and more pre smeared across her chin. Her hooves were curled firmly around her fat, black nuts, petting and massaging them as if inviting more cum to fill them. A flicker of magic from Twilight’s horn showed her that a small aura of magic was still working on Rainbow’s genitalia. What it was doing, she could only imagine.

“You’re acting way too strange, Rainbow,” Twilight went on, swallowing. No, she was not going to imagine herself swallowing a mouthful of that salty...musky...mouth-watering pre. She slurped up a line of drool from the corner of her mouth and for the dozenth time ripped her gaze away from the oversized organ. “I don’t want this spell to hurt you.”

“How could it hurt me when it feels so good?” Rainbow gave her fat nuts a squeeze, and giggled in surprise when a shot of pre splattered across her chest that could have made most stallions’ normal orgasms look small. “Mmff. C’mon, Twilight. Just one little lick. You know you want to.”

Twilight adjusted her hind legs again. She had to intentionally keep her rear from swaying, her rump bobbing from side to side at the sight of such a pure sample of masculine virility. The bedroom eyes that Rainbow Dash was giving her didn’t help either, and every part of her hindbrain was screaming at her to lay down and accept the good, solid rutting that her alpha stallion was offering her. “I...can’t,” she struggled to bite out. “This is...a test. Just a test.”

She caught sight of Dash’s cock again and gulped. It was swaying, bobbing lazily through the air as more and more pre slipped down the sides. And those balls… She hadn’t been aware that anything so big could even exist. Twilight swallowed, hard, her rational mind doing its best to come up with reasons to refuse.

Unconsciously, she took a step forward. “It’s a test,” she told herself, her voice wavering. “I can...test the efficacy of Rainbow’s new genitalia. Measure its…” She licked her lips. “Output.”

“C’mon, Twi,” Rainbow cooed. She petted her cock like it was a pet, albeit a rather large, smooth, and veiny one. “Just one lil’ lick.” Maintaining eye contact, she leaned down and drew her tongue up her shaft with a long, sensual lick.

Twilight shuddered. She stumbled forward with another step. Her marehood felt so hot… “Just a test,” she mumbled to herself. That musk was intoxicating. Could this really be what stallions had to deal with? But there’d never been a stallion like Rainbow Dash before, she amended. Such size, such virility, such lazy, absolute confidence. She could feel her friend’s aura enveloping her, guiding her steps forward, drawing her gaze to that prime, thick slab of meat…

“That’s it,” Dash murmured. Her voice was surprisingly soft. She watched as Twilight slowly leaned forward, her muzzle mere inches from Dash’s flare. “Just one lick…”

Twilight hesitated. Once more, Dash’s cock loomed in front of her muzzle. It filled her vision completely, seeming larger than life. Was she really doing this? She felt something tugging at the back of her thoughts—an urge, a doubt, as though she were doing something she shouldn’t. Wasn’t there something else she should have been doing right now?

But then a wave of arousal rippled through her loins, and Twilight nearly moaned. Her shudder sent her neck leaning forward, her lips parting and muzzle descending—until her mouth and tongue were wrapped firmly around the huge diameter of Rainbow’s enormous cock.

A glob of pre burst in her mouth, and Twilight moaned again. Oh, Celestia, Rainbow had been right. It was like nothing else she’d ever tasted. It was delicious, erotic, and invigorating, all in one. It was anything but fulfilling, though—she quickly found that she wanted more. She eased herself down onto her haunches as Dash’s hoof slid up her side, letting her lips wrap around another inch of Rainbow’s length.

“Like how it tastes, huh?” Dash asked, smirking. Her hoof slid around Twilight’s back and gave her shoulder blade a squeeze. “It’s good, right?”

Twilight made an effort to nod, The motion only sent her muzzle pushing another two inches down. Her jaw opened even wider in an effort to take in more of the enormous cock, and she swore she could hear it audibly creak. Another tablespoon of pre burst against the back of her throat and she moaned, gulping it down with a newfound eagerness. She could taste her stallion’s oncoming seed and arousal on every tastebud on her tongue, and was eager to taste even more.

“Mm. Mmff.” Rainbow grunted, her eyes fluttering shut as Twilight’s tongue lapped against the side of her shaft. “Now that’s some good stuff. But I think…”

Her hoof trailed down Twilight’s back until it found her flank. Twilight’s eyes widened, her cheeks flaring as Rainbow gave her plump ass a squeeze.

Rainbow’s eyes met hers. “...You can do better than that.”

Something like an electric shock passed between them. Twilight suddenly felt an urging, a need to please her stallion, to pleasure him in ways Dash had never before imagined. Her hooves slid up the sides of Dash’s shaft, finding the surface moist and slick. Rainbow groaned lustfully, giving Twilight’s ass another squeeze as Twilight did the same to her medial ring.

“Nngh,” Rainbow grunted, licking her lips. “Just like that.”

Twilight obediently complied. She could feel Dash’s hoof sliding up her back, then the back of her neck as she swallowed inch after inch of her friend’s fat, throbbing girth. She could feel the warmth of Dash’s breath against her forehead, and every pulse of blood in Dash’s cock made her jaw widen just a bit further. The warmth of Rainbow’s hoof on her neck didn’t distract Twilight at all from the magnificent stallionhood that was steadily drooling pre down her throat, a river that was only growing in volume by the second.

“That’s a good little filly,” Dash murmured, leaning in close. Her lips brushed against Twilight’s ear, and Twilight shivered. She could feel Dash pushing her forward, shoving her muzzle further down her vast length until she felt like her throat was bulging with her incredible girth. “Keep goin’, Twi. I want you to go all the way down.”

And down she went, the steady weight of Dash’s hoof forcing her ever-forward. Twilight felt tears coming to her eyes as the strain increased. She did her best to follow Rainbow’s orders, though, rolling her tongue up and down the shaft, each bob of her head pushing more and more of the other mare’s copious meat down her throat. The salty taste of precum covered her tastebuds as Dash’s penis filled her mouth even further. She actually had to reposition herself, leaning further forward to straighten out the stiff cock that was now pushing directly down her throat.

Twilight swallowed Dash’s shaft, letting it slide down her throat as streams of precum trickled down into her waiting belly. She moaned, her forelegs keeping her steady as her hooves stroked gently at the sides of Rainbow’s swollen, fuzzy sack. Dash kept nuzzling her mane, stroking the back of her neck as she guided her mare’s muzzle further and further down her shaft. Twilight suckled harder and harder at Rainbow’s stallionhood, her own cunt pulsing with heat as her thoughts pushed toward a single, defining thought: to help her stallion find release, and to be filled up with Rainbow’s seed.

As her lips met the surface of Rainbow’s groin, Dash groaned. Her hoof tightened around the curls of Twilight’s mane and tugged, forcing her muzzle back up toward the top of her shaft. Twilight’s lips were forced further apart as they neared the curve of Rainbow’s flare...and then pressed tightly together again as Dash pushed her head back down. Twilight’s tongue twisted, swishing along the underside of Rainbow’s penis as the other mare grunted and groaned with pleasure.

On Dash went, pushing and pulling Twilight’s head up and down the length of her cock to maximize her pleasure. Twilight, lost in arousal and submission as she was, was happily powerless to stop her mouth from being used, her throat apparently good for nothing more than a cocksock for Rainbow Dash’s enormous fuckstick.

The next time Twilight kissed Rainbow’s crotch, she could feel the underside of her chin pressing against the sides of Dash’s fat, swollen balls. Her cheeks pressed into them, Rainbow’s plump nutsack squishing beneath her dimples. Twilight moaned gutturally, and felt Dash’s cock twitch inside of her in response. Rainbow was so far inside of her—it was incredible. She’d swallowed nearly two feet of her friend’s cock, and felt woozy from the exertion. Lightheaded, even. Then Dash’s hips pumped forward, and Twilight felt her muzzle press tightly against the vast, churning depths of Rainbow’s overfilled balls. She could feel the seed sloshing inside.

Rainbow Dash’s grunts came with a steady, even beat. She snarled, growled, and moaned with pleasure, all while keeping Twilight’s lips planted firmly around her girth. Pre bubbled over Twilight’s lips, the steady stream of arousal slowly draining into her stomach. Twilight moaned; she already felt so full, and Dash hadn’t even cum yet. Every thrust of Rainbow’s hips drove another few inches of cock down her throat, and letting another spurt of pre down into her gut. She opened her eyes woozily and caught an eye of Dash’s fat, melon-sized nuts. Just how productive was this pony?

With a final, harsh grunt, Dash slammed Twilight’s muzzle down her shaft, her lips bulging around the girth of her medial ring. Dash’s hips bucked, and her member instantly flared in Twilight’s mouth. Twilight’s eyes flew open, but it was too late. Rainbow’s meaty girth had swollen in width, lodging itself firmly in her mouth and throat. Pints of cum rocketed from her tip, a waterfall of jizz that deposited itself directly into her belly. Twilight moaned, a hoof going to her gut as she felt it grow taut with Rainbow’s spunk. Each flare of Rainbow’s member brought a fresh load of jism shooting down her throat, fat globs of cream easily a pint each in volume filling her tummy up to the bursting point.

Her marehood was screaming at her, her whole body thrumming in time with the beat of Dash’s orgasm. Her friend’s thrusts went erratic, her massive balls slapping against her thighs as her hips jerked and twitched. Twilight’s vision blurred, her jaw cracking as Dash’s massive member forced its way in even further, spreading even wider as it bulged with the force of orgasm. There was just so much cum! Her every sexual instinct was surging, egging her on, worshipping the seed that her stallion was unloading into her.

When Dash finished, she groaned lustily. Then she pushed Twilight’s muzzle off of her cock. Twilight weakly complied, allowing her lips to pop off of Rainbow’s flare with another wet pop. A long rope of cum trailed from her tongue to Dash’s wide slit, thick and heavy with seed. Blinking rapidly, Twilight plopped back onto her haunches. She stared at Rainbow for a moment, her thoughts swimming.

“Um,” she finally said. She swallowed, a tablespoon of Rainbow’s cum following her saliva down into her stomach. “...Wow?”

Rainbow Dash moaned. “Aw, geeze,” she grunted. She was stroking her cock, which was still fully hard. “Aw, fuck.”

A final lurch of her shaft left Twilight’s cheek splattered with a messy glob of spunk. Still caught in something of a haze, Twilight lifted a hoof to her cheek, wiped it clean, then glanced down at it. It took an effort of will not to lick her hoof clean, not to lick every drop of that thick, sumptuous cream off of her fur—

“Looks like you agree,” she mumbled. Hazily, she pressed a hoof to her middle and shook it. Her belly was taut to the touch, full and stretched with what had to be more than a gallon of Rainbow Dash’s thick, virile seed. Her hoof sank into her belly with just a little bit of give; when she jiggled it, it sloshed happily, bouncing up against her thighs and rippling like a water bed. Twilight shivered at the sight of it.

“Wow,” Dash said happily. Her dick twitched, and she gave it a little pat. It throbbed in response, swelling up another two inches in length. “Wow…”

Alarm bells were going off in Twilight’s head. Her thoughts, sluggish as they’d been with arousal, were starting to turn once more. “Okay,” she said, taking a deep breath. “That was...impressive. But—”

“But what?” Dash cut in. She gave her plump sack a squish. If anything, emptying her balls down Twilight’s throat had only made them larger. “It was awesome, right?”

“It was...something,” Twilight said. “But it was also bizarre.”

Dash licked off a glob of cum from her cheek. “How so?”

“We both fell into that way too easily,” Twilight pointed out. She stroked her bulging belly gently and winced when her marehood burned even hotter at the sight. Nope. Looked like her arousal was still here. “Dash, you’re a good friend and all, but I never—that is, I didn’t think that we—”

“Would fuck?” Dash said. She sounded far too cheery about it.

“Yes!” Twilight said. Part of her pushed back against her doubts, arguing that anything that felt so good couldn’t possibly be bad. And she had enjoyed it, hadn’t she? And Rainbow Dash did look like she was—

She pushed back against those urges. “I’m just worried that this spell is doing something to you. To us, even!”

“Then why not test that out?”

That stopped Twilight right in her tracks. She blinked. “Um. What?”

“Y’know,” Rainbow said. “Cast the spell again. See if it happens a second time.”

Twilight stared at her blankly for a moment. “But I’ve already cast it on you, so who would we—” Then she got it, and blanched. “Oh, no. Oh, no. I’m very happy with the equipment I’ve already got, thank you very much.”

“You sure?” Rainbow raised an eyebrow at her. Smirking, she leaned down and nuzzled the flare of her cock...except given its new length, she barely had to lean down at all to do it. It swayed gently in her lap, the top ten inches of her bulging black stallionhood covered in a sheen of saliva, pre, and her own creamy jizz. “I thought so, too...but it feels really good.”

“That’s exactly why we shouldn’t!” When had I become we? Since when had the idea of casting the spell become interlinked with the promise of certain...mutual actions to take place directly afterward? Twilight felt the curve of her sloshing belly again and blushed. Goodness; another load like that and she’d look pregnant. Be pregnant, even—that is, if Rainbow Dash used the right hole the next time. Her hormones cried out in agreement, begging for more—

She shook them loose. The right hole? This was insanity! She clenched her thighs, trying to ignore the heat searing her loins. “What if I’m right and it is dangerous, Rainbow Dash?”

“C’mon, Twi.” Dash spread her hooves wide, neither one touching her dick. It leaned against her chest, the head poking up just over her shoulder. It drooled a steady stream of precum down her coat, smearing her fur with white. “You know me. Can you honestly say that if I suddenly got a super-humongous completely awesome penis, I wouldn’t use it for all it was worth?”

Twilight wasn’t entirely sure how to answer that. “Well,” she said quietly, slowly. “Perhaps not. But…”

“And even if you did react the same way...maybe you just needed a little encouragement to let that crazy little bookworm nympho out, huh?” Rainbow Dash’s grin became positively lecherous, her eyebrows waggling.

“Dash!” Twilight blurted. “That’s… No! I am not like that!”

“Says the mare who just finished sucking my cock,” Dash said, deadpan. Twilight blushed.

“Look,” Dash went on. She kept one eyebrow raised, and her hooves at her sides. Her voice was remarkably commanding; even if not for the enormous stallionhood that all but demanded attention, the confidence in her tone kept Twilight’s nerves from fraying on its own. “It’s science, right? You’re testing the spell, so might as well go all the way with it, right? Gotta get that sample...thingie.”

“Sample size,” Twilight murmured, correcting her. Her eyes were back on Dash’s dick, though, its gentle throbbing seeming almost like steady breathing. Her hoof drifted silently toward her marehood; as it brushed against her thigh, she shivered. Dash could see her completely, she realized: her plump pussy lips, winking madly as if begging for a proper stallion to fill them. Her gaze was swaying, too, following the lazy twitching of that oversized shaft like a pendulum.

And that sack… So huge, and full of even more cum. Twilight felt for her stomach and swallowed, hard. So much cum...and Rainbow Dash said it had felt so good. Wouldn’t that be worth experiencing, if only once?

“For science,” she told herself. “Just...just as an experiment.”

Rainbow grinned as Twilight’s horn began to glow. “‘Atta girl,” she said. She hugged her cock to her chest, her hooves facing only a bit of difficulty in reaching all the way around. “Let’s see what you can do.”

Twilight closed her eyes. This time, the spell came more easily, springing to mind as though it’d merely been waiting to be cast again. Once she’d cast it, she kept her eyes closed, squeezing them shut as her crotch reshaped itself, the magic surging through her body as the spell ran its course.

Finally, when she was sure it was done, she took a deep breath...and opened her eyes.

A very large horsecock stared back at her.

It was big. Like, really big. It poked up just past her muzzle, and was almost as wide as her leg. It swayed softly, as though caught in an imaginary breeze, and seemed to throb in time with her heartbeat.

Twilight stared at it dumbly, mesmerized. In the blur of her vision beyond it, she could make out the outline of Rainbow Dash’s member. Twilight’s was longer, it seemed, though Dash’s was slightly thicker, and her medial ring was a good inch and a half wider. Twilight raised a hoof to it, meaning to touch it—and then paused, hesitating. Her hoof fell to her lap...and landed atop her new, giant nutsack.

A moan instantly burst from Twilight’s throat. Right on cue, her new cock flared, and a glob of precum splattered all over her face. She froze, her eyes opened wide, unsure of what to do, or how to react.

And then it hit her; the lust. The arousal. Oh, Celestia, the arousal. Twilight actually moaned again, overwhelmed by the warmth of her new appendage. Her hoof squished a bit against her plump balls, sending another shockwave through her body. Her cock flexed, smearing another glob of pre against her muzzle. Twilight just gasped, her body twitching, her hips and thighs flexing as she struggled with the sudden demands of her new organ for sex, sex, sex, sex sex sex SEX—

“Feels pretty great, right?”

Twilight snapped out of it. Her vision refocused on Rainbow Dash. Sometime when she hadn’t been looking, Dash had stood up. Her basketball-sized nuts hung heavily between her legs, looking slightly squished between her knees. Her fat flare stuck out an inch or so in front of her chest, a steady river of pre drooling from the slit. Dash advanced toward her, her grin toothy and lecherous.

Twilight gritted her teeth, struggling to resist another wave of pleasure. It felt like her entire body was focused at the base of her shaft, her entire essence of being caught up in the rhythm of her throbbing member and churning, swollen balls. “This...this is insane. This shouldn’t feel so good.” She kept flexing her cock again and again, barely resisting the urge to whimper with need. But what did she need? Release? This was stronger than any sort of arousal she’d ever felt before.

Rainbow Dash was very close now. So close, in fact, that it almost seemed like she could bend down and kiss the tip of Twilight’s new member. But she didn’t. Slowly, she bent forward, her lips slightly parting. Twilight stiffened, wishing, hoping, praying that Rainbow would help her find relief.

Instead, Rainbow just breathed, her warm breath brushing across the curves of Twilight’s flare in hot, moist eddies. Twilight did whimper this time, her libido flaring up as Dash’s hot breath teased her to an impossible, ironlike stiffness.

When Rainbow pulled back, her smirk was on full view once more. “But it does,” she said, eyeing Twilight’s soft pants of arousal with amusement. “Doesn’t it?”

Twilight had gotten her hooves around her shaft and had begun to squeeze it. It weighed heavily against her chest; it really did throb in time with her heartbeat. Her fur felt so sweaty and damp with pre, so musky, so masculine in a way that she’d never thought she could feel before. Behind her, her wings were held stiff, so impossibly stiff that she might have feared flexing them too hard and snapping them off. She felt like a marionette, her strings held fast by some alien god of arousal and coitus. She bit her lip, following the playful darting of Rainbow’s gaze and just barely resisting the urges of her new, massive appendage.

Silently, she nodded. Then she felt Dash’s hoof on her shoulder.

“Get on your back,” Rainbow Dash said, looking down at her. A grin tugged at the corner of her mouth. “I wanna see how you look.”

Twilight caught herself obeying without so much as a second thought. She may have been more well-endowed than any stallion alive—even Big Macintosh, even her brother would have felt small and inadequate, even effeminate, compared to her—but the lazy confidence in Rainbow Dash’s voice asserted itself easily over her churning, disorganized thoughts. As lustful as her own musk might have been, Rainbow’s was heavier, stronger, sweatier. Maler. She could see from here that, while Dash’s shaft may have been two inches shorter, her balls were bigger than Twilight’s by a good third, and sloshed with Celestia knew how much more seed. She was the stallion here; dick or no, Twilight was her mare.

Being a herd species, rather than a pack one, ponies rarely had a concept of alpha. But some bestial, primal nature buried deep in Twilight’s mind knew that it was looking at one, and was hungry to service its will. She leaned back slowly onto her back, her wings spreading out beneath her in an instinctual gesture of submission.

Rainbow Dash circled her for a moment, her hoof-falls padding softly on the thick carpet. Twilight’s lip twitched, her eyes following Rainbow’s figure as she moved. Dash’s gaze may have been happy to rove over Twilight’s entire figure, but Twilight had eyes only for the thick, bouncing stallionhood swaying between her friend’s legs. She swallowed, pulling her forelegs up over her chest and wincing when her own cock blorped another glob of pre onto the carpet beside her head.

“Hm…” Dash stopped right above Twilight’s head, looking down at her. Twilight had to tilt her head back and raise her gaze to meet her eyes. The fat, black flare of Dash’s own cock interposed itself between them, a pillar of masculine meat filling up a good third of her vision. Dash’s smirk, though, was almost impossible to miss.

She gave Twilight’s cock a gentle prod, and Twilight moaned in response. “Not a bad cock,” Dash said approvingly. She giggled when Twilight erupted with another splurt of pre. “And productive, too.”

“Nggh…” Every inch of Twilight was aching, shaking, begging to play with her new toy, but something in Rainbow’s gaze kept her pinned in place. She shook faintly, arousal keeping her whole body stiff and hot.

“Nothin’ compared to mine, ‘course,” Dash said flippantly. “But…” She grinned and tossed her mane out of her eyes. “I wonder what your ‘big’ brother would think if he saw his ‘little’ sister with a not-so-little cock.”

She leaned forward and breathed on it again. Twilight felt like she could all but writhe in pleasure at the sensation. The mist of Dash’s hot, moist breath on her tip felt like heaven, her slit growing damp at the touch. Both slits, she realized; her marehood was still there, positioned just beneath her mammoth member, and it was aching and burning as badly as it had ever been. She bit her lip, whimpering softly.

“Dash,” she bit out, panting. “Please—”

“Please what?” Dash raised an eyebrow. “What, you think I’m gonna suck you off, too?” She chuckled at Twilight’s helpless look. “Well, I guess fair’s fair, at least. Especially ‘cuz you gave me this thing in the first place.” She prodded her own shaft playfully, giggling when it splurted its own gob of musky pre over Twilight’s muzzle. Her balls smacked heavily against her thighs as she stepped forward, her flare brushing against Twilight’s forehead. “Might as well help you out a little bit…”

Twilight whimpered as Dash’s hot breath brushed against her slit again. Then she moaned, her spine arching as Dash’s tongue darted out to touch her shaft. It wasn’t a lick, only a touch, but suddenly all of Twilight’s arousal, all of her need and all of her lust was focused in on the tiny, dotlike point where Dash’s tongue had touched her, that tiny spot where precum had been replaced by glistening saliva, where the warmth of another pony’s lips had so briefly brushed across her sex.

And then Dash licked across Twilight’s flare, and Twilight moaned, high-pitched and squealing. The other mare’s tongue scooped up a teaspoon of Twilight’s copious precum, then flicked across her head. Twilight groaned, her body twitching as Dash’s tongue worked its way into her slit, briefly stopping the flow of precum. Dash moved forward, her heavy balls slapping against Twilight’s forehead as she dug her tongue deeper into Twilight’s slit, the mare beneath her moaning and squirming cutely with each new wave of pleasure through her body.

When she felt something prodding against her lips, Twilight opened her mouth by pure reflex alone. As Dash’s tongue exited her slit, a bolt of pleasure surged through her. Her back arched again in pleasure—and she found herself with a mouthful of fat, hot marecock once again. She moaned around Dash’s cock, finding her head pushed back as far as it would go to make way for her friend’s endowment to push further forward down her throat.

It pushed her tonsils up against her esophagus, its sheer size and girth filling up Twilight’s jaw until it cracked. That familiar river of precum was pouring into her belly again, joining the small ocean of jizz waiting there. Twilight groaned, shifting as Dash eased her length down her throat, swallowing each new inch of cock as Rainbow teased her own shaft further.

There was just so much: so much cock, so much pre, so much musk. Every breath filled her lungs with nothing but the smell of Rainbow Dash’s own arousal, mixing with the scent of her own bestial lust. Twilight would have whimpered, but Dash’s cock had already pushed down most of her throat; her gigantic medial ring forced Twilight’s lips even further open as Twilight’s throat bulged hugely around her incredible girth. Twilight found her eyes watering, her breaths growing short as Rainbow’s massive cock dominated her face and throat with ease.

Tauntingly, Rainbow began to lap at the side of Twilight’s cock, slurping up as much of her musky pre as she could. Twilight groaned around the sides of Rainbow’s shaft, her tongue twisting and swishing along the underside of a particularly fat vein as the other mare slowly withdrew her member until only six inches were left inside. Then, with a grunt, Rainbow slammed her cock back inside, bulging out Twilight’s cheeks and throat with her meat until Twilight’s eyes watered with exertion.

Twilight soon found herself losing track of time, losing track, even, of where or who she was. Her thoughts, her libido, her very sense of self were wrapped up around Dash’s length, her heart pounding in time with each throb of the other mare’s stallionhood. She measured time by the thrust of Dash’s shaft down her throat, measured space by the grinding of her flanks against the carpet below. Her shaft may have been hard, but she felt soft, plush and feminine, curled around Dash’s hoof and impaled on her maleness like a broodmare, a toy, a bucket for cum.

She loved it, loved every rough, pounding thrust that brought Rainbow’s heavy balls, groaning with seed, bouncing off of her forehead. She loved the way Rainbow’s tongue curled around the edge of her flare, loved the way Rainbow’s hoof curved across her medial ring. In contrast to the brutal facefucking that Twilight was receiving, Rainbow’s touch to her cock was almost gentle. Teasing. Always taunting, always edging, but never fulfilling. Twilight’s hips twitched and her thighs tensed, eagerly pushing her cock forward, hoping for the warm embrace of Rainbow’s lips around her cock. But that release never came.

Instead, Rainbow had her own ideas. Twilight groaned, clumsily feeling over her cum-bloated belly as Dash facefucked her all the harder. With her head turned like this, Twilight’s whole upper body made for a clean, straight tunnel for Dash to fuck, and Rainbow was taking full advantage. Twilight’s throat was her cocksock, her mouth a simple fleshlight.

Twilight groaned again when she felt something bump against her hoof, a bulge shoving rudely against the taut skin of her stomach. Rainbow’s cock had gone all the way through her mouth, down to her gut, filling more than half of Twilight’s entire body. She could feel Rainbow all but rearranging her insides, her monstrous endowment making room for itself wherever it could. It pushed through a gallon of cum and precum, a sloshing ocean that swelled by the second.

Twilight’s own cock was steadily drooling pre; some of it was caught in Rainbow’s slurping licks, but the majority of it dripped down onto Twilight’s face. It caught on Dash’s cock, then dripped down the sides, rivulets of musky, clear pre that beaded on Twilight’s cheeks and forehead, covering her in the scent of her own arousal. Above, Dash’s teasing licks made Twilight’s loins burn all the hotter, her cunt and shaft clenching together with each wave of arousal that surged in her chest.

Above her, Dash was panting. “T-twilight,” she grunted, grinning with a faraway look to her eyes. “I—I’m getting real close. Nngh. Just...swallow my cock a little bit more…”

Her hips rammed a full foot of black, throbbing cockflesh down Twilight’s throat, bulging out her stomach again. Twilight’s cock lurched, her loins seizing up as her own release approached her. She might not have been under anything close to the pressure or stimulation that Rainbow Dash was enjoying right now, but the constant teasing and the sensation of being filled, of being used… That was enough for her.

With a mighty grunt, Dash bottomed out in Twilight’s muzzle. At the same time, Twilight’s loins flexed—hard. Twilight moaned around Dash’s cock as she came; the vibrations of her throat around Rainbow’s length only made the other mare’s oncoming orgasm all the stronger.

Dash came. A flood of cum of ludicrous proportions came rushing out from her bulging cockslit, the pressure in her churning balls forcing quart after quart of hot, steaming jizz into Twilight’s overstuffed stomach. Twilight groaned, her eyes rolling back as her own orgasm took over. Her cock splurted a half-dozen huge ropes of spunk over Dash’s face, covering her muzzle and chest in a thick, creamy white. Dash just grunted and seized Twilight’s mane by the ends, forcing her cock even further down Twilight’s throat.

Ulp. Ulp. Ulp. Twilight’s throat clenched and spasmed repeatedly around Dash’s length, each bulge of Rainbow’s shaft distorting her throat around its incredible girth and carrying a fresh load of baby batter down to her waiting stomach. Twilight’s mind was cloudy with the indomitable pleasure of her own peak; she felt as though her whole mind and body had become centered at a single, searing hot point at the base of her shaft, where pleasure, pain, and insatiable release were dueling in a clashing, soaring climax. The only other thing she felt was the steady pumping of jizz down her throat, and the steady bloating of her gut as it grew and grew to hold Dash’s enormous load.

Finally, their orgasms finished. Twilight’s shaft shuddered a final time, splurting one last glob of spunk over Dash’s face, then fell still. Dash’s hips shook, her cock twitching weakly in Twilight’s belly before, slowly, grunting in satisfaction, she pulled her tool out of Twilight’s throat and muzzle with a muffled schlick.

Twilight gasped for air. She coughed, a hacking exhale that brought sputters of jizz rocketing from her throat and onto her chest. “Oh, fuck,” she groaned. “Oh, fuck.”

Dash just panted happily. Her tool bounced softly against her chest. It looked suspiciously larger than it had just minutes ago; thicker, too. At least her balls had deflated a bit, if only slightly. Twilight glanced down at her overstretched belly and groaned. So that was where all of Rainbow’s load had gone. She prodded it with a hoof, watching in fascination when it sank a good inch down. She groaned, her arousal flaring up again as her belly sloshed and churned, struggling to digest the liquid meal that Rainbow had served up to it.

“O-oh,” Twilight whimpered. She bit her lip, her eyes fluttering as her cock twitched and flexed. The warmth of one afterglow was beginning to spread through her groin...but one organ in particular felt no more satisfied than it had been before. She groaned, her thighs twisting as she felt the heat in her loins redouble. Her marehood, it seemed, was tired of her mouth getting all the action. It wanted attention, now.

“F-fuck,” Dash panted, grinning lopsidedly. Her eyes were a bit unfocused, but she fixed them with a shake of her head. “Fuck, Twilight, but your throat is a tight fuck.”

Twilight coughed again weakly. She struggled to sit up, but found that her belly was too heavy to make that easy. She just flopped back down instead and groaned, her dick slapping wetly against her cum-bloated gut. A burp forced its way past her muzzle as her cock weighed upon her belly, the scent tinged with Rainbow Dash’s sex.

“I-it’s not my fault,” she mumbled, slurring a bit. “You’re just s-so big.”

“Big, huh?” A coy smile worked its way onto Rainbow’s face. She sat down on her haunches, her cock slapping against the top of her shoulder. “You like how big I am, don’t you, Twilight?”

Twilight shuddered. The lips of her pussy winked, her insides clenching in hopeful anticipation. She needed to be stuffed, fuller than she’d ever felt before, and Rainbow’s stallionhood drew her attention like a moth to a light. She hugged her cock to her chest, her soft belly squishing beneath it. There was only one answer to give here.

“Yes,” she admitted shyly, barely blushing this time. “Oh, yes, Rainbow. You were right. This just feels…” She shivered. “Amazing.”

Dash got back up to her hooves and stretched. Her spine arched much like a cat’s, and she sighed happily. “What’d I tell ya?” she said, smirking. “Looks like we’re both still hard, though.”

Twilight glanced at her shaft and blushed. Her towering stallionhood bobbed silently above her, covered in sexual fluids and saliva. Behind her, Rainbow Dash began wiping Twilight’s cum off of her face, happily licking it off of her hoof with each scoop.

“It does,” Twilight said, eyeing her shaft. Then another wave of arousal swept through her insides and she bit down on a moan. “B-but I… I don’t know if—”

“Know what?” Dash asked. “C’mon. You could totally go for another round.” She grinned toothily. “This is my fourth, and I’m still rarin’ to go.”

“Oh. Yes.” Twilight’s hoof curled around her thigh, and she tried to meet Rainbow’s eyes. “It’s just… Something else. I need...um…”

Rainbow Dash’s eyebrow went up.

“I need you to fuck me,” Twilight blurted. She was almost whimpering by the end. “Oh, please, fuck me. I need it so badly.”

“Is that it?” Rainbow purred. She advanced around Twilight’s said, stepping lightly as her cock swayed and bobbed beneath her. Twilight whimpered, eyeing that fat, black flare with desire. “You want me to rut you like the cute little filly you are, is that it?”

Twilight nodded quickly. It looked almost pathetic. Rainbow Dash chuckled at her. She was just above Twilight’s rear now, their stallionhoods parallel. Dash’s head was nestled comfortably between the cleavage of Twilight’s ballsack, her wide-set flare tapering off again its plump curves.

Dash gave Twilight a smirk. She stroked Twilight’s orbs gently, cupping them in her hoof. “Not a bad size, really,” she said idly, her smirk widening. “You’d make poor Shiny look like a filly with these. But they’re nothing compared to mine.”

She shifted her hips, causing her package to sway and smack against her thighs. Twilight’s gaze moved from the cocky grin on Rainbow’s face to the enormous, jet-black orbs dangling between her legs. They’d filled up once again since their last time being emptied, and were currently hanging down past her knees, absolutely groaning with cum. Twilight swallowed, unable to stop a line of drool from slipping down her cheek.

Dash gave Twilight’s testes a little smack. Twilight gasped in a mixture of pleasure and pain, her plump orbs rippling and jiggling with the force of the impact. What felt like gallons of compressed seed sloshed within, her cock throbbing harder and stiffer with each thump of her heartbeat. Twilight whimpered as Dash’s shaft throbbed atop her nuts, her engorged flare pressing against Twilight’s cum-filled belly.

“And mine are still pretty full,” Dash said slyly. “I guess I could give you a good rutting. After all, I doubt there’s a stallion in Ponyville that could hold a candle to me now.”

Twilight licked her lips. “Please,” she begged. Her marehood felt so empty, her cunt a hollow, burning cavity that needed to be stuffed full of dick. She tried to sit up, but couldn’t; she grunted, her belly bouncing a bit as it folded against the upper side of her shaft.

“Nah.” Dash’s hoof pressed down on Twilight’s stomach, forcing her back down. Twilight exhaled slowly, then groaned as Dash’s hoof sank into her cum-bloated belly. “You can keep lying down. After all, by the time I’m done with you…”

Her grin was the widest and cockiest that Twilight had ever seen it. The sheer confidence radiating from it sent shivers down her spine.

Dash’s hoof traced lazily around Twilight’s flank. “...you’ll be way too full to even get up, much less fly.”

Twilight grunted as Dash pushed forward; even with a cock, it seemed that Rainbow took no more interest in being graceful than she had before. She simply plopped forward, driving the air out of Twilight’s lungs from the impact.

Rainbow Dash’s cock pressed against Twilight’s, their twin shafts twitching from the contact. Twilight felt Dash’s larger balls weighing on hers; she could feel the other mare’s nuts churning with untold amounts of seed. A steady waterfall of precum, Dash’s mixing with hers, was drooling onto her chest and neck, leaving her fur matted and damp. Twilight moaned cutely, the added stimulation only making her dick harder...and her crotch hotter.

And then Rainbow’s lips were on hers, hot and shoving and hungry. Dash’s tongue wormed its way past Twilight’s muzzle, pushing into her mouth, tasting her, owning her. Twilight twisted beneath her weight, their cocks grinding together as Rainbow wrapped both hooves around her shoulder. Twilight’s hips jerked, her thighs flexing, her marehood aching as Rainbow tasted the jizz on her lips and lust on her tongue and found it...satisfying.

Rainbow pulled back after a solid minute of making out, leaving Twilight’s cheeks flushed and her heart thudding in her chest. Dash’s cheeks were red, too, though that cockiness never left her face. “Never done that before, have we?” she said, her chest heaving. Twilight shook her head dumbly.

Slowly, Dash walked her way down Twilight’s body; the flare of her cock bounced on Twilight’s squishy belly, then dragged slowly across it as Dash pulled her hips back. Twilight held her breath as Dash lined her cock up with Twilight’s hidden marehood, then grunted as she felt Dash slipping her member beneath her own balls, pushing them up into the air to get at the warm flower beneath.

Then she felt it: a hot, heavy weight prodding at her slit. Twilight bit her lip, waiting for Rainbow to begin. Dash didn’t leave her waiting long. With a heave of her hips, Rainbow shoved her flare inside Twilight’s dripping cunt, her fat, throbbing cockhead twitching at the sudden tightness.

Twilight’s whole body went stiff. She moaned, her inner walls clamping down around that huge, enormous stallionhood. She felt so stretched, so tight...and so full. She felt her entire marehood being stretched around Rainbow’s shaft, her womb compressing as Dash made more room for herself. She already felt full, and Rainbow couldn’t have been more than halfway of the way in.

“Fuck,” Rainbow choked out. Her hips twitched, and Twilight cried out. “You’re so tight.” Twilight moaned cutely as Rainbow’s hooves found her flanks, beginning to rub and squeeze her Cutie Marks. “”Nggh. Makes me wanna cum inside you right away.”

Twilight moaned again, seemingly incoherent. All her thoughts were caught up in the jizz swirling in her balls, every thump of blood through her searing marehood sending her whole mind shuddering and shaking with pure, unadulterated desire. She needed this, more than anything else. There was nothing filling her mind but sex: satisfaction, need, release.

Rainbow’s forward thrust paused when she felt Twilight’s marehood begin to tighten in resistance against her onslaught. “Unless,” Dash purred, “you can’t take any more of me. Maybe I’m just too big for a little filly like you.”

“No,” Twilight gasped. Her cock was rock-hard, quivering above her, steadily drooling precum onto her muzzle. She panted, crying out as Dash’s member lurched within her. “P-please. More. Fill me up more. I want to feel all of you inside me.”

“All of me, huh?” Dash said. Her grin widened. “Y’mean like...this?”

She jerked her hips forward, forcing another six inches of her length inside of Twilight’s cunt. Twilight squealed in a mixture of pleasure and pain, her vision going white for a moment as she felt her lower body molding around Dash’s shaft.

Rainbow began to pull out—and then shoved herself back in. Twilight inhaled sharply, then moaned again, her marehood spasming around Dash’s oversized stallionhood as she was thrust into again and again and again. Dash leaned forward, her tongue darting out to lick at Twilight’s own oversized stallionhood as she fucked Twilight silly.

“Celestia, but you feel good,” Dash grunted. She tightened her grip on Twilight’s flanks. Each thrust pushed another inch of length inside Twilight’s cunt; already, Twilight could feel her cum-bloated stomach distorting, distending, pushing upward to make room for Rainbow’s magnificent member. “I wonder if I could get you pregnant from this.”

Part of Twilight, something deep and primal, surged at the thought. Yes, it squealed, fill me up, pump me full of cum, give me your foals, make me your mare—

“Wouldn’t that be somethin’?” Dash said, her grin lopsided. “The Princess of Friendship, waddling around Ponyville and Canterlot with a belly almost bigger than her, filled with tiny little future Wonderbolts. Mmff. And every time your belly scraped on the pavement, you’d remember just how big I am, just how full I make you—”

Her slick cock pumped forward and backward with a regular, pounding rhythm. Twilight’s massive nuts were perched atop it, groaning with seed as Dash’s cock grinded against their underside. Twilight could feel her orbs churning even larger, fatter with unspilled cream, as Dash fucked the cleavage of her swelling, fattening ballsack along with her throbbing, abused pussy.

“Yes!” Twilight moaned out. She didn’t even know what she was saying yes to, exactly, but she knew that she wanted it. Loved it. Needed it, in a way that she never knew a mare could even need something before.

With each thrust, Dash walked herself a bit further forward, her weight pressing on Twilight’s torso until she was all but lying on her. Twilight grunted, feeling her gut squish out around Rainbow’s weight as the other mare pinned her cock to her belly. Even more of Dash’s shaft had penetrated her now; a quick jerk of Rainbow’s hips forward drove the final three inches of her member deep into Twilight’s cunt, spearing her.

Twilight cried out; Dash groaned. Twilight found her shaft squeezed between their bodies, an ever-increasing tightness that made her feel as though she were actually fucking the space between them. On one side was Rainbow Dash, her lean, muscular body crushing Twilight’s dick against her abdomen; on the other, was Twilight’s own belly, sloshing with cum, soft and plump with its liquid filling, and molding around the sides of Twilight’s cock to create the perfect fleshlight. Twilight twisted, writhed as Dash planted kisses all over her chest, shoulders, flare and lips, tasting her every part, owning them. as pleasure racked her body from every angle imaginable.

She could even feel the bulge of Dash’s cock in her stomach. It started in her middle, straining against her womb, then wormed up against her gut, her cum-filled tummy flattening where their sweaty bodies met. She could feel that bulge grinding against her own member, each throb of their cocks in sync, each thrust of Dash’s member into her marehood driving another throb of pleasure screaming through her own length.

Mine, Dash’s weight seemed to say, mine, mine mine mine MINE. And Twilight loved it, tossing and turning and squealing, worldless and mindless, as their sex ascended to new planes of pleasure. From the unfocused, dilated look in Rainbow’s eyes, she was feeling much the same, her cock jumping, twisting, throbbing in Twilight’s overstretched pussy. Each thrust brought Rainbow’s fat balls bouncing off of her own, their cum-stretched curves jiggling in time with snorts and groans and wet, meaty slaps.

Yes, she wanted to scream, this, this was what she’d wanted. What she’d needed. How could she have such a fool as to think this was a bad idea? This was amazing. Her cock contracted as her pussy lips twitched and spasmed. She could feel her insides tensing, clenching as she approached that inescapable peak. She was approaching a cliff of pleasure, the pressure in her womb and cock growing to an indescribable, incredible edge—

With a scream, Twilight’s back arched a final time. Her inner walls clamped down hard around Dash’s shaft, forcing it to curve upward as her orgasm fell on her like an avalanche. Waves of hot, searing fire pulsed through every inch of her body, every vein, as she came, harder than she’d ever cum before.

Volley after volley of thick white cum fired from her tip, which swelled and lurched between their bodies. It splattered her face and Rainbow’s with spunk, leaving their coats and muzzles dripping with musky, heavy jizz. Twilight soon found her vision obscured by her own cum, her cheeks dripping with fat globs of her own cum. Her breaths came short and hard as her whole body thrummed with the force of her orgasm, pints—no, quarts—of jizz firing from her dick as her pussy spasmed and clenched, rivers of sweet, tangy nectar streaming around the side’s of Rainbow’s own iron-hard shaft. She rode her feminine pleasures like a wave, screaming, twisting, writhing as she came again and again and again.

And then Rainbow came with her.

It was a subtle thing to begin with, barely even noticeable. It was a low, dangerous rumbling, a boiling of gallons of seed in balls too small to contain them. And then Twilight’s eyes were bulging, her insides clenching as Rainbow’s shaft swelled larger, thicker, bigger inside of her, the pressure building up like a stopped-off valve until she could barely even contain the sense of anticipation—

With a howl, Rainbow erupted. A tsunami of spooge came roaring forth from her fat-flared tip, her slit opening wide as it unleashed load after load of hot, steaming jizz directly into Twilight’s cunt and womb. Twilight squealed with her, riding out her own orgasm as Dash pumped more and more cum inside of her, filling her up, stretching her, making her look like a fat, round filly with all of the jism she was forcing inside. Was this what it felt like to be impregnated? Twilight’s thoughts spun, her head feeling faint as gallons of seed rushed in to fill her womb, her belly bloating, expanding, groaning with Rainbow’s neverending cream.

And then it was done. Twilight wheezed as Rainbow Dash went limp in her hooves. With a grunt, Dash struggled to push herself up—and then failed. She went tumbling off of Twilight’s big, rounded belly, its cum-bloated surface squishing beneath her weight as she rolled off to the side. Her softening cock came slipping out of Twilight’s soaked marehood with a schlip of pressure, letting a cascade of jizz come falling out behind it.

Groaning, Rainbow Dash did her best to rearrange herself. Twilight let her; she was too exhausted, too heavy, too satisfied to do anything more than stare up at the ceiling. Her sobriety was coming back to her, slowly, but for now she was content to rest as the afterglow spread through every vein of her body, a golden warmth that sang with the satisfaction of release. She breathed hard, her chest rising and falling as Rainbow arranged her body across hers, her head using Twilight’s belly as a soft, squishy pillow.

“Whew,” Rainbow wheezed. She coughed; between her legs, her massive cock twitched. “Wow.”

“Wow,” Twilight echoed. They lay there for a few moments: breathing, heaving, sighing softly in satisfaction.

Then Rainbow said, “Maybe you should...ungh...get back to that paperwork.”

The paperwork? Twilight’s brow furrowed. As her sluggish thoughts began to turn, she frowned, then blanched. Then, to her utmost surprise, she burst out laughing.

“I don’t think I’m in any shape to work on that right now,” she said, a few giggles slipping past her muzzle. She patted her round belly and watched it jiggle beneath Dash’s head like a waterbed; Rainbow moaned. “And I’m, at the very least, far too messy at the moment.”

Dash grunted. Weakly, she glanced over and shot Twilight a faint smile. “How ‘bout that flying lesson, then?”

The very notion was so absurd that Twilight just stared at her for a moment, blinking, before bursting out into a chorus of laughter again. Dash joined her, her lower, raspier chuckles mixing with hers in a harmony of amusement.

Twilight prodded her belly, smirking. “Somehow,” she drawled, “I don’t think I’ll be able to get off the ground.”

“So?” Dash said. She raised an eyebrow. “What now?”

Twilight patted her belly and groaned. “Well,” she grunted, watching waves and counterwaves bounce around her taut stomach, “I’ll need to update those spell files and issue a formal rejection to the professor who created this particular spell. Not because it didn’t work,” she added, seeing Rainbow’s confusion, “but because it worked, ah, a little too well.”

“Ah,” Rainbow said. She grinned. “Makes sense.”

Twilight nodded. “In the meantime, though…” She tried to stretch, but was interrupted by her belly gurgling. Evidently, it was having some difficulty digesting its oversized liquid meal. She blushed, also taking note of the huge splotches of cum covering both hers and Rainbow’s coats. “I think cleaning off is the first point of order.”

Dash gave her belly a lick. “Mm. Need some help with that?”

Twilight shivered happily. “I think a shower might be more expedient,” she said, grinning. “But, if you’d like to join me…?”

Dash’s smile stretched from ear to ear. “Now you’re talkin’.”