The Castle of Friendship’s library was, well, if you had seen it a few seconds ago you would have called it a mess, but in the blink of an eye it had been restored to a state of perfection that Twilight hadn’t seen since it had first sprouted from that tiny box given to her and her friends from the Tree of Harmony. And all of this was thanks to one pony, who currently stood across from her and her number one assistant with a humble smile on her lips.

Spike pumped a fist into the air. “Way to go, Starlight!”

And then the humble smile was gone. “Oh-ho, I’m not finished! I’ve discovered a very old spell, Similo Duplexsis.” The mare spread all four of her legs and crouched down in a common magic-casting stance. “When combined with Accelero in just the right way…”

Twilight smiled as her pupil’s horn ignited in a flash of blue and white. While the unicorn did still have some problems, namely the bit of an ego she carried over from her time as a super-villain and her lack of contact with anypony not a purple Alicorn or dragon, she had certainly come a long way. Plus, she’d be reminisce if she didn’t admit that the unicorn was a very, very good spell-caster and, with a thought that brought a rosiness to her cheeks, a very, very good-looking one at that.

Twilight dreamily sighed to herself. ‘Good at spells, a nice flank… Celestia above, she’s amazing!’

The mare finished her spell in a blinding flash of light, and once the stars had faded away from Twilight’s vision she watched as her pupil suddenly split in two. “You can literally be in two places at one!”

Twilight’s eyes widened and her mouth fell agape. Not just because Starlight had performed such a high-level spell with relative ease, oh no… It was because there were now TWO STARLIGHTS! Just the sight alone was enough to make her mouth water, and as her mind went to the only place it could go in such a situation she felt a heat start to build underneath her tail.

“Whoa…”

Twilight gasped and brought a hoof to her mouth, worried that she had just accidentally vocalized her amazement. ‘Wait, I didn’t just-’

“That’s...” Looking to her right revealed Spike in a similar state of shock. “That’s amazing, Starlight!”

The two Starlights smiled and started absentmindedly playing with their manes. “Aw, thanks, Spike! With a combination of spells like this, there’s no telling what somepony would be able to do in a single day! I mean, just think of all the practical uses there are for being in two places at once!”

Twilight felt her marehood wink behind her as she imagined the two Starlights working her body over at the same time. ‘Yeah, I can certainly think of some…’

“Yeah, I can certainly think of some…”, muttered the dragon beside her.

The Starlights perked up, both genuinely curious. “Oh, and what would that be?”

“Sex.”

Twilight’s eyes widened in shock as she turned towards her number one assistant. Not just because the relatively young dragon had just said such a thing, but because she had said it in perfect synchronization with him.

A blush crossed both Starlights’ face as they took a surprised step back. “S-sex!? Why… Why would you say such a thing?”

“Um, well…” Twilight sheepishly rubbed the back of her mane.

“Well, uh…” Spike did the same.

Twilight grimaced. 'Well, this is embarassing...' She sighed. How was she going to save face with her pupil now?

“Well, you see, Starlight…” She sat down and started gesticulating with her hooves. “Sex is a… It’s a…” She nudged Spike in the side, who jumped away with a startled yelp. “Tell her, Spike.”

Spike scoffed and threw his arms up into the air. “Pff, are you kidding me? She’s YOUR pupil! Why don’t YOU tell her!” He smirked and pointed towards the two flabbergasted unicorns. “Come to think of it, why don’t you tell her how you’ve been writing in your diary that you want to take her upstairs and fu- hmph!”

Twilight leaned in and, holding his mouth closed with her magic as she glared daggers into his very soul, growled right in the young dragon’s face. “I told you never to read my diary again...” Her face turned quizzical. “Wait, were you just about to say fu-”

“Uh, Twilight?”

Twilight snapped back into her seated position with a far-too-wide grin splitting her face in two, but not before she gave her assistant another nudge in the side with her magic that nearly sent him toppling over to the floor. “Sorry, just had to talk with Spike about something important…” The dragon pouted and crossed his arms. “But, uh, yeah. S-sexual intercourse would probably be a good place for such a spell.”

Both Starlights took a step forward. “Twilight, I-”

Twilight blushed and averted her eyes. “Not that I’ve ever thought about such a thing, of course, but I’m sure that being able to stimulate multiple spots of your partner's body would make the experience that much better, right?”

The perfectly synced mares took another step. “I mean, sure, but-”

Sweat was starting to form on Twilight’s forehead. “I mean, a lot of ponies, not me, of course, probably have daydreams about having intercourse with two or more ponies at once, and this sort of spell would make such a thing so much easier to-”

“TWILIGHT!”

Twilight jumped back, eyes wide with fear. “Wh-what!?”

The Starlights smiled. “Do you want to have sex with me?”

Twilight’s mouth fell agape even as her tail shot straight up into the air. “B-bwah?! S-sex!? With you!? Why… Why would you say such a thing?”

“Well…” The Starlights took another step forward, putting them right in front of Twilight and Spike. “I mean, sure, I was surprised about the idea at first…” They each lifted a hoof and stroked both their cheeks. “But I can certainly see what you mean.”

Twilight looked at her pupil with wide, disbelieving eyes. “Y-you do?”

“Mhmm.” The twin-unicorns nodded. “Of course, there’s only one way to see if this combination of spells would actually work in such an environment…”

Twilight felt her clit wink into the air behind her. “T-testing?”

Both Starlights smirked and leaned in, one whispering into Spike’s ear as the other did the same in Twilight’s. “Lots and lots of hard, sweaty, rigorous testing...”

A bead of liquid excitement dripped down the inside of Twilight’s thigh. “I… I..." She licked her suddenly dry lips. "I think I’m up for some... testing… What about you, Spike?”

Spike could only nod his head, though if one took a peek between his legs they’d see he was certainly raring to go.

The Starlights grinned. “Good… Now, just wait right there…”

And then, in a blink of an eye, the two identical mares were gone.

Twilight swallowed around the lump in her throat. “St-Starlight? Where’d you-”

A sudden force picked both her and her number one assistant up into the air, carrying them both faster than they had ever gone straight towards a table set in the corner of the library. Before Twilight could even open her mouth to scream they were deposited onto the cold, hard surface, and before she could let out a surprised “Eep!” she found herself pinned to the table by one feisty looking unicorn.

“Now then..." Starlight sensually licked her lips. "Let’s start our experiments…”

Twilight blushed as she looked up at Starlight’s smiling visage, the unicorn’s face framed by the magical lights hanging high overhead. “Um... O-okay-hmph!”

In a lightning-quick flash of movement Starlight darted in and placed her lips against Twilight’s, using the Alicorn’s momentary shock to slip her tongue into her slightly agape mouth. Both pupil and mentor moaned as their tongues wrapped around each other, eyes fluttering closed and heat seeping into their cheeks as they embraced like lovers atop the table.

The kiss lasted until the burning in their lungs forced them to separate, leaving both ponies gasping for breath as they stared into one another's eyes. Starlight shot Twilight a smug looking grin, the kind of smile that said “You’re about to get fucked. Hard.”, and after putting a hoof against the Alicorn's chest to keep her pinned to the table she walked over her prostrate form.

“Now then…” Starlight picked up one of Twilight’s hind-legs and scooched forward, putting the sopping wet lips of her light-purple pussy right next to Twilight’s darker ones. “Let’s see how well this works…”

A wet shlick echoed off the library walls as Starlight thrust her hips against Twilight’s, grinding their marehoods together in a lewd display of fat, meaty lips and shimmering, succulent juices. Twilight moaned as she felt her pupil’s pussy press against her own, the deep, guttural sound morphing into a high-pitched gasp as, at the apex of her thrust, Starlight’s clit winked out to lay a kiss against her own. Before she had a chance to catch her breath Starlight had already thrust again, sending Twilight into a spasming fit as the unicorn ground their bodies together in the most pleasurable way imaginable.

“O-oh, Starlight!” Twilight’s head started uncontrollably shaking back and forth as her pupil's hips became a blur beneath her. “Oh my gosh! Oh my Celestia! This is-”

“Shh…” Starlight smiled and nodded her head across the table. “I think there’s a better use for your mouth right about now…”

Twilight glanced up, just in time for the lights hanging overhead to be blocked by the second Starlight’s big, fat, light-purple plot. A groan sounded just past the heavenly ass descending towards her face, and just before her vision was taken from her she leaned her head back and, viewing the room upside down from between the second Starlight’s legs, she saw the somewhat stubby purple limbs of her assistant at the mare’s front.

Both Starlights moaned as one sat back on Twilight’s head, though it was somewhat muffled by the draconic cock shoved between the second one’s lips. Spike had his claws on either side of the mare’s head as he thrust his hips against her face, sinking his dragonhood back and forth between her lips as his scaly balls slapped her in the chin. Lines of drool seeped from the corners of both Starlights’ mouths as the taste of dick spread across their taste buds, and the dual sensations of Twilight’s pussy rubbing against her own even as the same Alicorn ate her out was like nothing she had ever felt before!

Twilight moaned into the thick mare lips pressed against her face, tongue buried as far as it could go into her pupil’s snatch in an effort to pass on as much of the electric pleasure coursing through her veins as possible. The unicorn sitting on her head began grinding her hips against her face, scrunching up her muzzle and sending rivulets of her juices down her chin. That, combined with the constant grinding against her pussy, sent Twilight’s eyes rolling to the back of her head, reducing the Alicorn to nothing but a vessel of pleasure for the two Starlights to use as they saw fit.

Spike, meanwhile, had begun to really get into face-fucking his half of the Starlight twins. The dragon had curled his body around the mare’s face, head next to her horn and feet on their tippy-claws as he slammed his hips against her lips. Each time the dragon’s cum-laden orbs slammed into Starlight’s chin he’d let out a ferocious sounding hiss, and before long he, too, had seemingly lost control of his body to the haze of lust in his mind.

The Starlight between Twilight’s legs grinned at the writhing mass of ponies before her, and as her magically-created copy picked up her hind-end to reveal the near passed-out form of the Princess of Friendship she had an idea. Laying down on top of her mentor, Starlight began to lick off her own juices from the mare’s face, moaning as her taste buds were assaulted by her sweet ambrosia. Of course, while it was a nice bonus, cleaning off Twilight’s face wasn’t the real reason for her change in position.

With her on top of Twilight, her horn was pointing straight towards her other self's sopping wet pussy, the lips bright pink from the Alicorn’s exceptional tongue-work from just before. Keeping herself as still as possible, the Starlight on top carefully sat back onto the bottom’s horn, the spire of smooth bone easily piercing her outer gates to sink through her folds like a knife through butter. Within moments Starlight felt her own marehood press against her forehead, drops of her excitement matting down her mane and fur as she sat pierced on her own horn.

Twilight, eyes wide as she watched the scene from below, gasped as the Starlight on top of her resumed her gyrations against her hips. With them laying belly to belly, however, the sloppy makeout session between their marehoods was no longer possible. The pouting ends of their pussies, however, were close enough to kiss like a pair of long-lost lovers, causing the bulbous buttons of their clits to wink out against each other in rapid succession.

Spike, meanwhile, was starting to feel the toll on his young body. Beads of sweat trickled down his forehead and back, tickling his scales as they dripped down to the floor. His chest heaved with each thrust he made against Starlight’s face, and whereas he had been hissing or growling each time he bottomed out inside her mouth now he could only draw in another panting breath. The muscles in his legs screamed at him to take a break, and with his climax still a ways off he wasn’t sure he’d have enough in the tank to finish.

Starlight, apparently sensing the dragon’s distress, grabbed him in her magic and pulled him away, causing the spit-covered cock in her mouth to slip from her lips. She looked up at him, butt bouncing up and down on her own horn, and gave the dragon a warm smile. “I-if you’re getting tired-ah!” Starlight shivered at a particularly hard thrust. “Why d-don’t you go around to the other side?”

Spike looked at her, questioningly. “Wh-what?” He took a step back. “What do you-?”

He paused as movement beneath Starlight’s legs caught his eyes, and what he saw as he looked down took his breath away. Twilight, flat on her back at the center of the table, had wrapped her hooves around the other Starlight’s midsection as she sloppily made out with her pupil. Drips of mare-juice dropped from the Starlight he had been facefucking's puffy pussy, splattering onto both the mares’ beneath her to create one sloppy-looking pile of ponies.

Dazed, Spike made his way over to the opposite side of the table on wobbly legs, erection bobbing between his legs as it searched for its next target. His balls felt full of seed, the cum-silos ready to dump their loads at a moment’s notice. The cool air in the room caressed his spit-slickened shaft as he walked, sending shivers up his spine and drips of pre drooling from the tip. It felt like it took ages for him to make the arduous journey around the table, the constant gasps and groans coming from the rutting pile of mares on top of it goading him on-

And then, what was only seconds later, he found himself looking at something he never expected to see even in his dreams.

Two perfectly pristine marehoods, sitting atop one another with the fat bulbs of their clits mashed in a kiss. Drooling rivulets of their juices intermingled before rolling down the insides of their thighs, dripping off their bodies to form a puddle on the crystalline table below.

Spike licked his lips. Where the trip around the table had been difficult, having to make a choice between the two sets of dragon-heaven was even more so. Twilight’s lips looked thick and juicy, the kind of pussy that would wrap around his cock with open arms and carry him into the kind of climax most males would only dream of. Starlight’s was just as impressive, tight enough to squeeze his shaft and milk the cum straight out of his balls while being soft enough to caress every inch of his cock in just the right way.

“S-Spike…!” The dragon glanced up to find the second Starlight, blush on her cheeks as she rode her doppelganger’s horn, looking back at him over her shoulder. “I-if you can’t choose, just put it between us!”

Spike’s dragonhood flexed at the thought. His eyes fell back down to the point of contact between mentor and pupil, where the flesh of their marehoods intermingled to form a tight looking hole. He imagined shoving his cock between the two ponies and how the mare’s continued gyrations against one another would sandwich his pride between their bodies. He imagined them both moaning his name as their clits kissed the side of his shaft, the gushings of mare-honey as they climaxed onto his dick. And then, as the final straw, he imagined his dragonhood painting them with his seed, splattering his very essence across their lower stomachs as they all writhed in endless pleasure.

Spike nodded his head, his eyes never leaving his target. “Y-yeah… Sounds… good…”

Starlight returned the nod. “G-good. Now, get to it! I d-don’t think I’ll last much longer!”

With that, the mare turned back around and threw her head back to moan towards the ceiling, the seemingly never-ending thrusts against her other self building to a crescendo. Spike quickly made his way between both Twilight’s and Starlight’s legs, climbing on top of the table and crawling on his knees to put his cock at the perfect level between their marehoods. He teasingly rubbed the tapered tip of his shaft up the center of one and then the other, coating it in enough of their juices to make it glimmer in the light.

And then, with a deep breath, he pushed his dragonhood forward.

Stars flooded the dragon’s vision as his cock slipped between the two mares’ mashing marehoods, their clits peppering kisses up the length of his shaft as he pushed himself to the hilt. His balls slammed into Twilight’s pussy with a wet slap as he bottomed out, causing the Alicorn to moan into Starlight’s mouth as a lightning bolt of pleasure raced up her spine. The seeping lips had done an amazing job at lubricating his shaft as it slid through, and as he took a moment to catch his breath his juice-covered cock flexed against their lower stomachs to wipe away some of their liquid-honey.

And that was only the first thrust!

With a long, drawn out groan and an even longer pull of his hips, Spike extracted his cock from between the two mares until, when the tip of his cock was sandwiched between their clits, he reversed direction and pushed back into the warmth of their bodies. The dragon soon built himself into a rhythm, pushing forward with enough force to send his balls crashing into Twilight’s marehood like a pair of wrecking balls and pulling back as fast as his body would allow. He even had the presence of mind to bring his claws in on the action, one pulling and tugging on Starlight’s tail as the other worked his digits in and out of their clenching cunts.

The Starlight kissing Twilight like there was no tomorrow pulled back with a gasp at one such claw-thrust, resulting in her horn pushing against the walls of her copy's fluttering passage as she sat against her forehead. It was a strange sensation, feeling your horn sheathed inside your own marehood as a dragon thrust against your clit. Strange but very, very good, and before long Starlight felt a tenseness start to form in her lower stomach.

Letting her head fall next to Twilight’s as the two mares rode out their pleasure, Starlight breathily whispered into the Alicorn’s ear, “I-I’m close, Twi… How are y-you?”

Twilight was apparently a bit further along than her because no sooner did she get her words out that the Alicorn’s horn ignited in a flash of light. The Princess of Friendship shriek as every muscle in her body began to rhythmically contract, vision fading to white as the draconic dick between her legs continued to saw against her clit. Her marehood clenched once, twice, and then, with a moan that became muffled as Starlight pushed her mouth against hers, Twilight’s orgasm crashed into her like a tidal wave on the shore.

Spike’s teeth grit together as he felt the first gush of marecum splatter against his balls, completely coating his scaley sac and, as he pulled his hips back, the underside of his cock. The sound of Twilight moaning filled his ears, causing his libido to go into overdrive as his hips became a blur beneath him. The once far-off tinglings of his climax suddenly barreled down on him like a runaway train, one that, when it reached its final destination, ripped a line of fire from his lungs as he tilted his head back and moaned towards the ceiling.

Starlight gasped as the first blast of dragon cum rocketed out of Spike’s cock to coat her lower stomach, the gooey strands sticking to her fur and painting her lower-half white with his seed. She gasped again as the dragon suddenly wrenched his cock back from between her and Twilight’s bodies, so much so that the tip of his shaft slipped past their grinding clits out into the open. A third gasp would prove to be her final because, as Spike’s orgasm continued, a thick dollop of seed arced through the air and landed smack dab on her clit, sending a final, Equestria-shattering blast of pleasure straight up her spine that sent her over the edge.

"OH! TWILIGHT! SPIKE!"

Spasms raced down Starlight's spine as her marehood clenched down on air, sending jets of her marecum streaming out of her pussy that splattered across Twilight's own, rapidly-winking lips. The doppleganger sitting atop her horn did much of the same but, after only a few gushes against her face, she lost enough of her concentration that it vanished into thin air. The continuous clenching of her muscles forced her to thrust against the mare beneath her, grinding their clits together as they blissfully moaned together in a symphony of lust. The pleasure soon became too much, and in an effort to pass some of it along she shoved her lips against Twilight's and wrapped her tongue around her mentors. But, like all good things, all three climaxes would come to and end, leaving both mares panting into each other's mouths as their orgasms gradually faded away.

Starlight shivered one final time as her climax came to an end, and as beads of sweat mixed with her own cum dripped from her face she pulled back, looked down at Twilight, and smiled. “Phew..." She leaned in and playfully licked a bead of mare juice from her mentor's face. "So, how was that?”

Twilight chuckled between deep gulps of air. “Heh heh… I’d have to say that Accelero and Similo Duplexsis happen to work rather well in this situation.” She glanced over towards her assistant, who plopped down beside them with a sigh. “Wouldn’t you think, Spike?”

Spike, collapsing flat on his back next to the two mares, wearily lifted a claw into the air and gave them a big thumbs up. “Yup…”

The mares chuckled, and with matching sighs they embraced in a hug, each closing their eyes as their respective afterglows gently caressed them into sleep.

At least until Twilight’s eyes popped open. “Oh, and Starlight?”

Starlight wearily cracked open one of her eyes. “Yeah?”

Twilight smiled and rubbed a cheek against her beloved pupil’s. “You still need to do those friendship lessons with my friends…”

Starlight frowned. “...Fuck…”

And that is the story of how Starlight failed to get out of friendship lessons by having raunchy sex with her mentor.

Author's Notes:

This one felt longer wordcount-wise when I was writing it, and I'm not sure why... Which is strange, because I didn't have to rush this one as bad as some of the others (just the climaxes and the end, which I came up with about five minutes before posting this). Weird...

Oh well, hope you guys/gals enjoyed it!