A deep breath escaped Horizon’s chest as he leaned back tenderly onto a haybale. His hooves throbbed like a metronome as he tilted his head back, sighing and letting his eyes flicker shut.

He’d been hard at work all day. The farmhoof chores he’d been putting off to fulfill his bet had come back with a vengeance, and that was on top of the community service hours he’d had to do to fix up the bar. He hadn’t actually touched any of the wooden planks that he’d used to board up the hole he’d made -- being a unicorn came in handy when it came to manual labor -- but he could swear that his horn had splinters just the same.

A familiar weight on his chest stirred him back to wakefulness. After the events of two nights back, most of the ponies had lost anything resembling a libido, and probably wouldn’t get one back for another few days. Though it may have looked it, Horizon hadn’t been solely responsible for the massive flood of bodily fluids on the bar floor.

He exhaled, savoring the brush of warm air against the head of his sagging cock. For him, however, life was business as usual. Whatever he’d done to his stallionhood had let his reserves spring back within a mere half a day. Admittedly, that was notable for him, as he usually had to stop to beat off at least once every two hours with his balls swollen back to their current soccer-ball size. Even with that momentary respite, however, he’d soon found himself back on the farm and, somehow, alone with his monstrous sex drive.

The tip of his hoof brushed against his medial ring, which was itself almost wider around than his leg. He shivered, a spark going up his spine. His balls throbbed in a sympathetic reaction, their refreshed contents eager to be drained once more.

It was obvious that he needed to let off some steam. Even so, he was too tired to be creative, and there was no harm in keeping things simple. A tired smirk spread across his face as he slowly ran his hoof up and down his shaft, the other resting on his nutsack. He didn’t need anything freaky or magical. He just needed some sweet, sweet release.

Horizon closed his eyes and went to town.

As his hoof met the flared head of his member, he pictured Apple Blossom.  He saw her in his mind's eye: the soft curves of her flank; the slight lilt of her lips; the flutter of her eyelashes, and the inevitable squeal of pleasure and surprise when she would look down at his rock-hard, throbbing stallionhood.

By some quirk of cosmic luck, ever since word of his  “enhancements” had gotten around the farm,  he hadn't caught a single glimpse of Blossom, whether on the farm or off.  Admittedly, their schedules didn't quite mesh up, which was why he had admired her from afar.  Ever since he had tried out his spell out his package, though, he had been seeing so much less of her that it seemed like she had almost been avoiding him.

He waved the thought away with a snicker.  No way; it had to be coincidence.

But that wasn't important right now.  What was important was his dropping erection, and the feel of her imaginary rump beneath his hooves.  Already, his monstrous shaft was oozing precum, making a sizable puddle on the barn floor.  His testicles throbbed as he massaged them.  He bit his lip, imagining the feel and shape of her cheeks hotdogging his massive member.  Idly, he wondered what she would grow around if she had the choice.

He would give it to her if she asked, of course.  He had already been more than generous with his spell around the farmhand village, but for Apple Blossom, there were few things that he could see himself refusing to do…especially if it involved his " area of expertise."

Maybe she wouldn't go for the ass.  It was a little too obvious, he thought.  Maybe she would go for her mammaries -- big boobs were “in” like never before, he remembered reading in some trashy magazine -- or perhaps she would think of something else.  He'd heard of things like mares with big lip fetishes, or fetishes for big, smelly hooves.  Somehow, though, those didn't seem right.  He didn't find anything wrong with them, really, but it just didn't seem to fit with Apple Blossom.

His mind drifted.  The speed of his stroking increased, until he was vigorously pumping away at his throbbing, dripping shaft.  He gave a short grunt as a spurt of pre splattered on the ground beside him, a sudden burst of heat flaring up in his groin.

What if there was something that she wanted of him that he couldn't grow?  He frowned.  So far, his grow-me-up spell had worked on all the subjects but his friends had bothered to put in front of him.

As he slowed his stroking, making small circles around the head of his member, a thought occurred to him.  All of the fruits, vegetables, and animals that he had used the spell on had grown up wholesale; that is, the whole thing had grown.  When he used it on ponies, though, only certain parts grew: a rump, a pair of breasts, a cock and balls.  Had he ever grown a whole pony?  He didn't think so.

Unbeknownst to Horizon -- as was so often the case -- a light green glow had already sprung up around his horn, flickering with each lustful grunt.  Slowly, the green magic spread out over his shoulders, down his torso, and soon over his entire body.  He didn't notice; his eyes were closed, teeth biting down hard on his lip as he imagined riding a giant-assed Apple Blossom.

He gave a soft moan as the green glow tightened around him, spreading a familiar warmth through his body.

His muscles felt tight, his entire body throbbing and twisting with the blood in his cock. With each inhale of breath, his whole body felt tighter; with each exhale, it felt looser than ever before. Horizon grit his teeth, feeling strength surge through his arms as he tightened his grip on his stallionhood, his gasps grunts and gasps coming more and more frequently now -

Wait. He hadn’t made that gasp. He slowly opened his eyes.

There was a mare standing in the doorway of the barn. Her coat was a bright, cheery yellow, her Cutie Mark a blur of red. He squinted, wondering why she seemed so far away...and why he seemed to be staring down at her, even though he could’ve sworn he’d been sitting on the floor. Had he moved up to the rafters at some point?

As if irritated at the pause in stimulation, his oversized cock throbbed once before giving off a spurt of precum. Horizon sputtered as the warm, cloudy liquid splattered over his snout, a bit dripping down from his forehead and onto the floor. Wiping the pre off wasn’t hard - though it was a bit sticky - but when he glanced down to see where the drops had fallen (because as much as he thought he’d be used to it by this point, seeing the massive puddles he could make of pre alone had never failed to drive him wild) he noticed that his flanks were still planted quite firmly on the barn floor.

When he looked back up, the warm pre still dripping from his snout, two things occurred:

First, he realized that the top of the haybale he’d been leaning against was now level with his chin.

Second, the Mark on the mare’s backside resolved into a pair of bright pink flowers. A pair of very familiar flowers.

“Um,” Horizon said.

“Um,” Apple Blossom said. “I...guess this is a bad time to get some supplies.”

“No - wait!” Horizon stumbled up onto his hooves - and the floorboards creaked and groaned beneath his newly-massive weight. His cock slapped loudly against his thighs, already drowning the haybales beneath his belly with pre. She took a step away, and he shrunk back. “I mean… Uh. One sec.”

One shrinking spell later, and he was nearly eye-to-eye with Apple Blossom. His monstrous cock and balls were even a bit smaller as well, though it might have been too much to ask him to admit that some part of his mind had done it on purpose.

He flushed as she stared at the ground. “I’m sorry,” he blurted. “I didn’t realize - I didn’t think that anyone was around. I’m really sorry.”

“Don’t be.”

“I wasn’t - wait.” He stopped. “Don’t...be?”

When she looked up again, her own cheeks were burning a brighter red than his. “It’s...fine,” she said. “I should’ve knocked or something.”

“Knocked to enter the barn,” he said. “Right.”

She chuckled, and he bit his lip, trying to hold in his chuckles as well.

“So,” Blossom said. “I have a bit of a confession to make.”

“What?”

Her hoof traced slowly through the sawdust on the floor. “When I first heard about how you were using your new magic, I felt...confused. I didn’t realize that you could use it on ponies, you see.”

“That makes two of us,” Horizon said. When Apple Blossom stared blankly at him, he chuckled uneasily. “I mean, I didn’t expect it either. Complete surprise. Really.”

A soft smile touched her face. “It shocked me too,” she said. “I guess I never really expected myself to be so much of a...well, prude. When I heard about your new spell, my first instinct was to stay away from it. When I heard about the ponies you were seeing, my first instinct was…”

Horizon gulped.

“...to stay away from you.” Apple Blossom stared at the floor.

“I, uh.” Horizon licked his lips. “I didn’t think - “ No, of course he didn’t think. He didn’t think at all. Maybe he liked Apple Blossom, yeah, but maybe she liked him back. And he just never even asked her out or anything, just started fucking everything in sight. Stupid, stupid, stupid -

“But I changed my mind,” Blossom blurted out. “I...didn’t feel right, judging you like that. It wasn’t like you’d made any promises to me, and…” She sputtered for a moment and then looked up at the ceiling. “Ugh! And maybe I kind of liked you, okay?”

“Well,” Horizon said. “I, uh.”

Go on. Say it, you moron.

“I guess I kind of liked you too,” he said.

There. Done.

They were both quiet for a moment.

“Another thing that I thought about earlier,” she said, “was that bet I heard you made.”

“Oh.” Horizon blinked. “Right. That one.”

“Every pony on the farm,” Blossom said slowly. “Sure, I bet you were drunk, but from the sounds of it, you’ve been keeping up to that vow.”

“Heh. I guess.”

“Every pony,” she said, taking a step closer, “except one.”

Horizon swallowed. That look in her eyes, that sway in her step, that lift of her tail -

“Well,” he said as she took another step. “I’m sure there’re some ponies that I haven’t - I mean, I don’t know if I - and it’s not really that important, and - “

She lifted a hoof to his mouth and shushed him. “So,” she said. “You can make whole ponies bigger?”

“I...I guess,” he said.

She seemed to consider that for a moment. When she let her hoof fall back to the floor, Horizon noticed it was trembling.

“Good,” she finally said. “Then how about...me?”

And then he was on the floor, with her straddling his chest and her lips pressed against his. And his horn was flickering green, and he wasn’t even thinking about it and before he knew he’d already cast the spell.

And her weight on his chest was already heavier than it’d been just a moment ago.

Apple Blossom pulled away from the kiss with a flourish and looked right into his eyes.

“I was an idiot,” she said, panting, “for not doing this sooner.” She glanced back at his cock, which - by this point - had already reflexively grown back to slightly more than its usual length. She smirked down at him, and he flushed. “And it looks like we’ll have to take care of you as well.”

His cock was throbbing, and his legs felt like they were on fire. Horizon gasped as Apple Blossom slowly ran her hooves down his length, planting tiny kisses down on each and every inch. His hooves twitched up in the air, and a shiver went down his spine. He’d always enjoyed sex before, but this, with Apple Blossom, seemed more intense than all the rest put together.

The instant he got his senses together, though, he went to work returning the favor. He leaned up and kissed Blossom’s thighs, making sure to suck hard on her smooth, bright coat. She gasped on top of him and he grunted as her weight suddenly increased on his chest. Her legs grew even longer until they were planted directly on the floor - still bent at the knee - and her pussy grew until it would have dwarfed any normal mare’s.

Now that, Horizon decided, was a challenge. He grinned and got to work.

He ran his tongue along her thighs until he reached her outer lips, and slowly lapped at the juices already leaking there. He gasped as she took the tip of his head in her mouth, her tongue circling around his slit. Precum was already dribbling out of him in generous amounts, and he could imagine it filling her mouth, bulging her cheeks, dribbling out onto the floor -

He redoubled his efforts and stuck his tongue deep inside Blossom, wrapping his lips around the clitoris and sucking, at first gently, and then harder, his head swaying from side to side as he teased her. Blossom shivered, her legs tightening around Horizon’s head - and then pushing him down even further as a green aura surrounded her, growing her body even further.

Horizon let his head spring back with an audible squelch. Blossom’s sweet, tangy taste still ran down his chin, her musk nearly overpowering to his every sense. He looked up at her flank - an enormous, incredible flank, already the size of Lily’s overgrown ass, and yet still perfectly in proportion to the rest of her body.

And what a body it was. She had to be nearly twice his size now - as tall as Celestia, but as thick and as powerfully muscled as any earth pony, with a flank and legs to match. She took a break from her own work on his cock - his head coming free from her tight, teasing lips with a pop - and looked back at him.

“You like that, little stallion?” she asked, fluttering her eyelashes.

“Oh, yes,” Horizon said quickly. “I mean, oh gosh yes right there - “

Blossom had already turned back to his cock and planted her lips directly on the tip - but she hasn’t stopped there. Horizon could feel his shaft’s head twitching inside of her mouth as he filled her, her massive body rocking back and forth as she descended past the tip and directly over the head - and further still.

The green aura returned, and Horizon winced as her weight redoubled. It almost felt like she was crushing her chest, her dripping mound teasing him with each gasping breath he managed to take. For its part, though, his loins didn’t seem to mind at all - if anything, his tool had become even more swollen with fluids and arousal, his entire body seeming to thrum with the beat of blood through his crotch.

Horizon bit his lip, his head tossing back as he struggled not to cry out. Blossom had managed to take not just his entire head, but also his entire shaft into her mouth - all the way down to the base. He swear he could see her winking at him as her tongue roamed its way over his churning balls, his massive cock filling every inch of her mouth - but not even quite reaching to her throat. He could hear her gulping down every spurt of precum he produced, and imagined it going down to fill her massive, growing belly. It’d be like a drop in a bucket.

And that only made his balls produce even more.

He hardly even noticed it when he came the first time, his thrusting hips meeting the sweet warmth of her lips as his cock, never one to be outmatched, finally grew out to meet Blossom’s esophagus. He could feel her jaw widening, shifting to adjust his incredible length...and then his head flared, and he was groaning, snorting, and thrashing as cum flooded out from his groaning balls to fill her.

He would have noticed - but he was busy with his own task, his hooves massaging her enormous thighs as hard as he possibly could as his tongue dove right back in, attacking her pussy. He could feel her vagina winking against his chin, could feel the shifting of pure, powerful muscle against his tongue as it wiggled against her clit. He rubbed his snout against her outer lips, smelling, feeling this pure scent of her, and then she was moaning, her hips bucking into his chest as her tail swished over his face. He lapped up as much of her marecum even as she gulped down his, making sure to get each drip of sweet, sticky nectar even as it flooded all over his torso.

“Mmff,” she moaned, her lips pulling away from his cock with a wet pop. “Salty.” She grinned at him, his sticky ejaculate still dripping from her lips in long, thick ropes.

And then she shifted her weight, and her head was directly above his. He grunted, all the air being knocked out of him with the sudden shift - but his cock was already hardening again, rising up and prodding against Blossom’s slightly swollen belly.

“Aw, geeze,” he said. “Usually…”

“What?” She blinked at him, but then glanced down at her stomach and chuckled. “Oh, I see how it is. I’ve heard how you leave some of your mares as big as balloons by the time that you’re done.”

“It’s not fair!” Horizon said, doing his best to pout. “I must’ve filled you with almost two gallons of cum, but it hardly even made a difference!”

Blossom leaned in close to him and let her breath wash over his chest, her massive muzzle filling his entire field of vision. “Maybe I’m just too big for that now.”

“Maybe,” Horizon said stubbornly. He crossed his hooves over his chest and huffed. “I can just grow my package bigger.”

“What, and try to do to me what I heard you did to the bar?” She snickered as his cheeks turned red. “I don’t think so. From what I’ve heard, you couldn’t even move. It wouldn’t be any fun for me to try and - “

She nudged his hooves to his sides and nuzzled against his chest. He could feel her immense weight over him, could feel the warmth of her body as the hairs of her sagging underbelly brushed against his towering cock.

“ - play with you like that.”

“And if I wanted to be played with?” he offered.

“Still boring,” she said. “Come up here and join me.”

“Up - what?”

“Grow up, Horizon.” She snorted and tossed her mane over her shoulder. “Literally. I’ve never felt so...powerful.”

“Powerful?”

“I’m bigger than Celestia herself! Gosh, what a rush.” She held one oversized hoof beside his hoof and prodded him slightly. “You were like this when I came in. Didn’t you feel it?”

“I...guess I was interrupted,” he said. “What does it feel like?”

“Like a million bits,” she said. “Like there’s nothing in the world that could bring me down. I’ve never felt stronger, more intense, more aroused - “ Her cheeks flushed for a second, but after a moment, she chuckled. “Gosh, I even feel too big to be embarrassed about it.”

“That good, huh?” Horizon asked. She nodded. “Then I guess I’ve got my choice made for me, huh?”

“You betcha.” She wiped a milky strand of cum from his face and flicked it on the ground. “Now, let’s see how big a pony can get.”

Horizon closed his eyes and reached for his magic.

It had been easy before, when he’d called on it unconsciously, and it came just as easily now. He felt the magic flow into him, warming his limbs, his torso, his stallionhood. His heart beat loudly in his chest, and he could feel his cock slowly swelling even farther as the magic flew through his veins. He groaned, shifting his weight as his bones creaked, his muscles pumping and swelling, his shaft heavier and heavier atop his balls.

By the time he opened his eyes, he was meeting Blossom’s. She was still straddling him, his shaft now planted firmly in her pussy, but this time, he could see the bulge it made in her stomach with each tiny motion; could see her slowly swelling stomach as precum flooded into her. This time, she had her hooves hanging around his shoulders, her muzzle rubbing against his own.

“How’s it feel?” she asked.

Horizon glanced down at his hooves. Without even thinking about it, he let it fall to the floor - and grinned as he felt and heard the floorboards shake and creak in response.

He cracked his neck, looking up at the rafters - which, all in all, didn’t seem so far away anymore - and inhaled, feeling the wind rush into his larger, more powerful lungs.

“Twice the size of Celestia,” he muttered, arousal flooding through his head like a wildfire. “Fuck.”

“Only if you’re ready,” she said. She leaned in close and nipped his neck, slowly working her way up his neck to his chin and finally his mouth. He felt his lips open to hers and tasted her tongue, felt her hooves holding him close, felt his hooves crawling up her hips, up her back, tightening their grip until he could feel his own cock-bulge pushing against his chest. He could feel her tongue dueling with his, could feel the sweat dripping down his chest as his head twisted and swayed, trying to force his mouth even further inside of hers -

And then he opened his eyes, and he was looking down.

Blossom’s lips came off of his with a pop. She was breathing hard, her chest heaving up and down. It took her a moment to realize that she was looking up.

“Twelve feet not enough for you, you size queen?” She was grinning the biggest shit-eating grin he’d ever seen.

“Guess not.” Horizon shrugged, and then almost shivered as he almost felt the pure power coursing through his limbs. Fuck; looking down on her now, he could swear that he’d be nearly thirteen feet at the shoulder if on his hooves. As it was…

He looked back up to the rafters. As it was, his head was already a good nine feet off the ground, a whole three feet above Blossom’s. Goddesses, but if he were only two feet taller, she’d be no taller than a foal to him - and a normal pony even smaller still. He snickered as he realized that Plow couldn’t be taller than a single one of his swollen testicles at this point. He snickered even harder when he started to imagine what Plow would look like with all of the cum contained in just one of those testicles sloshing around in his stomach.

“Something funny?”

“Just a joke I remembered,” Horizon said. He put a hoof around Blossom’s head and held her close to his chest. His hips slowly pumped up and down, sliding his five-foot cock slowly up and down her pussy. She moaned with each pump, his cockhead clearly visible through even her enormous abdomen.

“Wanna...share?” she grunted out between thrusts. He could feel her getting wet again already, though whether that was due to her own juices, his overflowing pre, or both, he couldn’t tell.

Horizon recalled his mental image of Plow, muscled belly swollen outward with so many gallons of cum that he’d more than doubled in weight.

Oh, yes. He had plenty to share. But he wasn’t big enough yet.

“You,” he grunted, bringing back his magic, “have no idea.”

His bones started creaking again, his limbs growing longer and thicker as his head grew farther and farther away from the floor. He held onto Blossom tight with both hooves, keeping her impaled on his cock as he thrusted into her again and again. The floor shook with each thrust, his hips crashing down to the floor with incredible force. The very wooden beams around them groaned and squealed as two tons of heavily endowed stallion collided with the ground again and again.

And Horizon kept growing.

He reached eighteen feet, then twenty. By now, Blossom really was a foal to him, her small - yet still incredibly large, relatively speaking - body teetering back and forth on his lap as his cock slammed into her again and again. Her belly was swelling even further now, gallons and gallons of pre pouring out from Horizon’s tip as his balls contracted into his body, getting ready to release the entire load at once.

“More,” Apple Blossom panted, her tongue hanging out of her mouth. “Harder. Bigger. Not big enough!”

And Horizon obliged.

His horn brushed the tips of the rafters, nearly twenty-five feet off the ground. He groaned as he moved to simply sliding Blossom’s taut body up and down his shaft, using her as nothing more than a cocksleeve. Her eyes nearly rolled back in pleasure as he fucked her more thoroughly than anything had ever been fucked, her moans nearly drowning out his needful, growling grunts.

By the time his head hit the roof, all restraint was gone - and the ocean flooded out.

Blossom screamed, though whether in pleasure or pain Horizon couldn’t tell (though some part of him genuinely hoped and prayed for the former), as enough cum to fill barrels and barrels of cider roared through his cock and exploded out the other end, escaping to the one place that it could find: Apple Blossom’s womb.

Blossom squirmed, speared on the tip of his cock as her stomach bulged, swelling with every passing second as more and more of Horizon’s seed flooded into her. He could hear it churning, sloshing in her belly with each twitch of motion. Her stomach swelled beyond anything he’d ever seen, until it actually pulled his cock forward and down with its sheer weight.

To her credit, though, not a single drop spilled forth from her pussy, tightly clenched around his titanic cock as she was. Instead, her stomach only swelled further until it was larger than the rest of her body. By now, she was just over the size of a single one of his testicles.

It was at this point that that same concerned corner of his mind regained some manner of control and managed to summon up Horizon’s magic one final time. Apple Blossom moaned as the green aura surrounded her once again, her marehood convulsing wildly around Horizon’s shaft as she, too, began to grow.

“Mmff,” Horizon grunted, grinding his cock - and Apple Blossom - against his chest, trying to milk out every last drop of cum. Now, though, Apple Blossom had started to outpace the flood of cum, her body swelling larger even as her stomach seemed to shrink in size. Horizon barely even noticed the shift in weight, but soon enough, she was within a head in height of his own size, and the aura had spread to include him too.

The roof put up a good fight, put it gave up after just a few seconds of Horizon’s horn straining against its reinforcements. The two giant and growing ponies burst through the roof with a crash, their muzzles by now locked together again as the final throes of Horizon’s orgasm rode themselves out.

Horizon finally groaned and opened his eyes. For the first time in over a month, his balls felt completely and totally empty; his stallionhood completely and utterly limp. But, for some reason, his entire body felt suffused with a warm glow, his muscles sore but relaxed. He startled as he felt something pushing closer to his chest.

“Now that,” Apple Blossom murmured, snuggling in closer to him, “was the fucking of a lifetime.”

They’d crashed through the barn, evidently, and kept right on growing. Down beneath Apple Blossom’s right flank, Horizon could just barely make out the wreckage of the loft; beneath his own, he could feel the haybale piles if he just shifted around a little bit. It was strange, then, that most of what he could feel was limited to Apple Blossom’s body pressed against his, her mane playing against his chest as she breathed softly in the afterglow.

“Absolutely,” he breathed. He could still see - and feel - her stomach bulging out with cum. It wasn’t swollen to the insane size it’d been before, but it was still full to the point of apparent pregnancy, the sloshing, warm cum easily audible as she shifted against his side. “Unless…”

She smirked sleepily up at him. “Same time next week?”

Horizon took a deep breath. “...Sure. But first, we might need to find a new - “

“The barn!”

Both giants glanced down at the source of the tinny, almost fragile-sounding voice. Tiller stood at the center of the barnyard, a set of muddied overalls on his chest, a bucket at his side, and an expression of complete and utter horror on his face. More and more ponies were beginning to pop up out of windows all around the farm, both to see the destruction and to see Tiller’s impending meltdown.

As Tiller began to hyperventilate, Horizon turned to Blossom and chuckled, the ground shaking as he shifted his weight. “Think we’re going to need to help clean up?”

She punched him on the shoulder. “Only if you want to keep your job.”

“So that’s a maybe,” he said, and held her closer.