Bust Busters

by Jest

Rating: mature
Tags: Twilight Sparkle, Anthro, My Little Pony: Friendship is Magic, Alternate Universe, Porn, Fetish, Rainbow Dash, Random, Sex
Length: 8244

Rainbow Dash's bust has always been a point of annoyance to the athletic mare, for no matter how much she works out her titanic tits never shrink. Thankfully Twilight has a solution for that.

Rainbow Dash's bust has always been a point of annoyance to the athletic mare, for no matter how much she works out her titanic tits never shrink. Thankfully Twilight has a solution for that.

Kinks Futa, stomach bulge, hyper endowment, cum inflation, breast and ass growth, anthro, and probably more.

This (in-process) story was viewable by patrons (One of whom commissioned this story) for a few weeks already, head on over there if you want to be the first to see updates like this one!

Published 2019-02-02 22:50:02 UTC
Last updated 2019-02-02 22:50:02 UTC

This is gonna work, right?

Rainbow Dash’s eyes shot open, her mind instantly realizing that something was off. Glancing at her alarm clock she quickly realized what exactly was off about her morning.

“Goddamnit.” She grunted, throwing aside the blankets and revealing her naked body for the world to see.

The pegasus had always been short, and slim, that was until high school when despite her best efforts, she filled out significantly. So much in fact that her clothes no longer fit after a certain summer, leaving her with the body of a porn star.

Leaping out of bed, Rainbow Dash made certain to grab her enormous breasts, gripping them tightly as she sprinted over to the closet. Throwing open the door, the pegasus quickly reached in and grabbed her triple H bra and hefted the enormous peice of fabric over her shoulders and wings, before clicking it in place and feeling the massive weight of her tits lift slightly. It was small, but something the pegasus revealed nonetheless.

Digging deeper she quickly threw a short over her head, one that would be around three sizes too large for her, rendered the perfect height due to her titanic tits, revealing only a thin slice of midriff. Rainbow Dash didn't have time to color code, and simply grabbed a pair of white panties at random, slipping them up to her ass before stopping.

“Not again.” She growled, gripping the panties in both hands before heaving it up over her sizable ass, only barely managing to fit it into place without the fabric snapping under the pressure.

The pegasus growled irritatingly, feeling the distinct way that the thin pair of panties strained to contain her butt. Glancing over her shoulder, Rainbow Dash glared at her butt, noticing how it stuck out from her usually slim physique like a sore thumb. “I really hope this cure Twilight cooked up works.” She muttered.

Grabbing a pair of shorts, the girl quickly threw those on, followed by a pair of socks, and finally an average twist tie to hold her hair up in a ponytail. With all that done, She turned and looked herself in the mirror, admiring her pronounced abs, and trying to ignore her bulging, porn star esque tits and ass. Closing her eyes the girl imagined those parts of her gone, a thought that brought a smile to her face.

“Alright, let's make this a reality.” She whispered to herself before closing the closet door and leaping down the stairs.

The pegasus threw open her front door, and leapt into the air, the ensuring backdraft ensuring her front door closed behind her. Opening her wings wide, she pumped hard, making a beeline for Twilight’s library, a smile on her lips.

The pegasus landed with a thump, one hand over her massive breasts and ensuring she didn't accidentally take one of her own eyes out, again. Skidding to a stop, the pegasus withdrew her hand and sprinted the last of the way up to the door, her reinforced sports bra the only thing between her and a black eye.

Throwing open the library door, Rainbow Dash sprinted into the library, eyes wide as she looked around the room. “Twilight are you there?” She yelled.

The purple head of her friend poked up over a small pile of books, revealing the alicorn’s surprised face. “Oh hey Rainbow Dash, your early.”

“Early? You said ten o'clock.” Rainbow pointed out.

Twilight chuckled. “Yes but I just assumed you would be late and scheduled accordingly.”

The pegasus growled, stomping her way up to the alicorn and the desk she sat at. “Yeah well I’m here. Can we get this started now?”

“I suppose. Just give me a second.” The alicorn turned, quickly adding a few more notes in the sign out book before shutting it and standing.

“Alright. I left the serum in the basement, I… Rainbow Dash?” Twilight asked quizzically, noticing the way the pegasus’ eyes lingered over the librarian’s body.

Rainbow Dash could hardly pull her eyes from what she saw, her gaze lingering down the girl’s enormous cleavage, until it rested on the sizable lump hidden just beneath the alicorn’s ankle length skirt. The pegasus knew well that Twilight was a rather endowed dick girl, but she had never seen her friend wear anything with cleavage, and Rainbow Dash quickly found herself staring at the nearly two and a half feet of half erect cock now making her friend’s skirt start to tent.

Covering her crotch with both hands Twilight frowned, using her magic to bring her friend’s attention back up to her eyes. “Yes Rainbow Dash?”

“I err..” the pegasus scratched the back of her neck awkwardly. “You look nice today?”

Twilight rolled her eyes and chuckled, having gotten used to Rainbow Dash constantly staring at her tits, and cock. “Thank you, now can we please get this started? I’m eager to see the results.”

“Right.” Rainbow Dash muttered, following close behind the other girl as she walked towards the basement door, the pegasus’ eyes drawn to the slight bulge that her friend’s balls occasionally made against the back of her dress.

Twilight cast a quick glance over her shoulder before chuckling and rolling her eyes. “Oh Rainbow Dash.” She muttered, knowing full well where her friend was staring.

The alicorn had to push down the erection she could already feel building inside her, forcing her mind to focus on the task at hand. This means a lot to Rainbow Dash, don't get distracted now. She reminded herself.

Together the pair made their way into the basement, the door closing and locking behind them with the help of Twilight’s magic. Once alone, Twilight began busying herself trying to find where she had left the serum while Rainbow Dash looked around, gazing curiously at the many beakers and other experiments still going on around her. Just as she was about to poke something she probably shouldn't, Twilight suddenly gripped her finger in the magenta glow of her magic.

“I wouldn't do that if I were you.”

Rainbow Dash pulled her finger back and glowered at the girl. “Yeah whatever.” Her eyes suddenly went wide and she surged forward. “Is that it?”

Twilight lifted up the small cylinder of greenish liquid. “Yes, this seems to be it.” The alicorn smiled, running a finger down the side. “And to think, this might be a way to lose weight without the need for exercise, diet or anything really.”

Rainbow Dash rolled her eyes. “Yeah yeah, you did that speech the other day already. Metabolism super whatever whatever now gimme.”

The pegasus’ grasping fingers caught a whole lot of nothing as Twilight pulled the cylinder from her reach. “Now hold on a second. Did I tell you about the potential side effects last time?”

“No?” Rainbow Dash frowned.

T“Well that's what we are going to test for today.” Twilight began, keeping the liquid from the reach of the handsy pegasus. “This might not even work properly, but this first usage will go a long way in ensuring it eventually works so-”

“Don't get your hopes up.” Rainbow Dash rolled her eyes. “Yeah I know, you've only said that like a hundred times already.”

“Well it's true.” Twilight pointed out.

Rainbow Dash sighed, tapping her foot impatiently. “I know Twilight, I also know this might be the only way to ever get the slim body I dream of so hand it over already.”

“Fine, but don't say I didn't warn you.” Twilight remarked, offering the serum to the impatient girl.

Rainbow Dash’s eyes went wide and she grabbed the cylinder and threw the entire thing back in a single, solid gulp. Only for her eyes to bug out of her head and the girl to grab her throat. “Augh, did you have to make it taste that bad? It was like drinking dish detergent, or something.”

Twilight rolled her eyes. “I told you it was a prototype Dash. Right now I’m trying to make sure it just works. Maybe later I will have the time to work on flavor.”

“Whatever.” The pegasus’s smile grew and she eagerly bounced from foot to foot. “So, how long does it take?”

Twilight tore her eyes from the other girl’s massive jiggling chest and shook her head. “What? Oh, uh ten minutes or so? It shouldn't be long.”

“Augh, in all the comics I read it always works right away.” The pegasus whined.

“Yeah well, this is real life, not a comic book. So suck it up buttercup.” Twilight shot back.

“Fine.” The pegasus whined, crossing her arms over as much chest as she could before pouting and putting her hands by her side, giving up on being able to even be pissed without her tits getting in the way of things.

Twilight chuckled softly to herself before grabbing a nearby notebook and retrieving a pen. Flipping it open to the middle of the book, the alicorn clicked the pen and began taking notes. “Taste is sub optimal, perhaps too much laundry detergent.”

“Har har Sparkle.”

Twilight giggled. “Well, while we wait why don't you answer a few questions.”

“Fine.”

“First, what would you consider is-”

“-and that's all the questions I had. Is it still not working?” Twilight asked hesitantly.

“Yeah.” Rainbow Dash grouched. “Are you sure this is gonna work Twilight?”

“I was sure about twenty minutes ago, now? Not so much.”

Rainbow Dash opened her mouth to continue to whine only for a second heat to explode out of her, making her eyes open and a shocked expression to cross her face. “I think it's working!”

Twilight instantly shot up in her chair, grabbing her pen and paper quickly, ready to take notes. “What do you feel?”

“A warmth that starting in my stomach and spreading out to my…” The pegasus stopped, her hands going to her stomach as she stood there in stunned silence.

“To your where?”

Rainbow Dash wanted to speak, to move, to do something, but the sudden and overwhelming heat demanded that she stand there, stunned to silence and unable to do anything. It was heat unlike anything she had ever experienced and it centered almost perfectly on her pussy, giving her the feeling of going through the most intense heat she had ever experienced. “I’m so hot all of a sudden, it's like…” Rainbow moaned, gripping the front of her shorts as a pained expression crossed her face.

“Like what, Rainbow Dash are you okay?” Twilight watched on in terror as her friend keeled over, gripping the front of her shorts, her face twisting into an expression of confused terror.

“Are you alright? Should I call a doctor?” The alicorn asked nervously, glancing up the stairs only to stop when a hand suddenly gripped her arm. Twilight looked down, noticing the sudden and intense look her friend was giving her. “Rainbow Dash?”

“It's nothing, I’m just really, really hot.” Rainbow Dash smiled weakly. “It's fine, really.”

“Well if you insist.” Twilight glanced down at the other pony for a second before turning her attention to the table, wherein she began to take notes at a rapid pace.

Noticing her friend was distracted Rainbow Dash licked her lips, her gaze drawn down to the alicorn’s skirt that was still tenting slightly, the closeness they had shared enough to begin making her cock harden. Twilight was nothing if not polite though, and though Rainbow Dash had seen the girl’s dress tent like this a thousand other times, something about this time made her gaze linger and her mouth water.

This time she wasn't happy just looking, she wanted to touch it, to feel it inside her, filling her with it's massive girth. Glancing up to the distracted girl one last time, Rainbow Dash quickly realized that her friend was off in her own world, her quill working at a breakneck pace as she took notes.

The pegasus shrugged, figuring it was a alicorn thing and whatever she had going on would probably fly right over her Rainbow’s head.

Turning back down Rainbow Dash licked her lips one final time before gently gripping the hem of Twilight’s dress and gently lifting it. She glanced up, watching Twilight for a moment and quickly realizing she didn't seem to notice the pegasus’ little excursion up her skirt. With a fiendish gleam in her eye the pegasus slipped her head under the skirt and beheld a sight so magnificent that her knees went weak after a mere glance.

It was massive, at only a slight chub it was already eight glorious inches, already as thick as Rainbow Dash’s fist and with no panties in sight. Not like any panties could possibly contain the sheer magnitude of Twilight’s titanic sack or the no doubt double digit reaching litres of semen that sloshed around inside them. The girl shuddered in delight, the heat burning inside her growing hotter for every second she spent staring at the massive peice of girlmeat sitting between her friend’s legs. As she watched she could see it pulse before slowly beginning to retract into the alicorn’s sheethe.

With a panicked look Rainbow Dash lurched forward and did the one thing she never thought she would do, swallow several inches of her friend's surprisingly delicious cock. Instantly the alicorn stiffened up significantly, both her legs, and her cock, wit the appendage surging from it's sheethe and down Rainbow Dash’s throat. Which in turn only added to the tightness that Twilight now felt wrap around her cock, as well as making the already weak pegasus nearly collapse at the sensation, her throat already stuffed full of dick in mere seconds.

The pegasus could feel hands around the back of her head, scrambling desperately in order to grip the eager girl and stop her from swallowing more of Twilight’s delicious cock. “R-rainbow.” She muttered.

But the pegasus was no longer paying attention to anything she said, and instead dove deep, gripping Twilight’s legs and using it as leverage to push herself until finally she felt the distinct sensation of sheethe against her nose. Breathing deeply the girl shuddered once more, the potent scent of a needy stallion filling her airways and causing the already raging inferno in her loins to reach new and unparalleled heights of arousal.

The hands scrambling at the back of Rainbow Dash’s head suddenly stopped, the alicorn’s half hearted plea to stop turning into a moan of pleasure. The alicorn’s entire body seemed to slack for a moment, then just as Rainbow Dash was about to ask what was going on, she felt it.

Nearly a foot of cock suddenly erupted from the girl’s sheethe and shot down the pegasus’ throat, filling it beyond anything she had ever experienced. She wasn't exactly a slut, but neither was Rainbow Dash a pony anyone would call inexperienced, even still, all her exes and even dildos could not compete against the monster cock now residing in her throat.

It filled her in ways she couldn't even put into words, leaving her moaning and shuddering around the massive length of girlmeat, her body struggling to adapt to the nearly foot and a half of dick down her throat.

Already she could feel her jaw begin to creak as she felt it forced wider than ever before, something she eagerly helped with, not wanting to accidentally bite her friend. It was all she could do just to keep opening her mouth wider and wider as she felt more and more girl meat slip past her lips and stretch her body.

The hands that gripped Twilight’s legs nearly slipped off, so baffled was the pegasus by just how good it felt to have her throat so thoroughly violated. It was a pleasure unlike anything she had ever known and some part of her knew that nothing would compare to a goddess like Twilight, and that all other partners would be a paltry comparison.

Then, just as soon as it started it stopped, with Rainbow Dash left blinking and confused as she noticed she was no longer beneath the girl’s skirt and were instead sitting on the floor a few feet away. A confused and angry Twilight was staring her down, horn sparking, her skirt tented so extremely that it could no longer hide Twilight’s long, and surprisingly shapely legs.

“Whuh?” Rainbow Dash muttered weakly, a hand gently running down the bulge she had just barely felt in her throat.

“RAINBOW DASH!” The alicorn boomed, stomping over to the pegasus and accidentally making her cock bob up and down as she did, taking some of the anger wind from her sails.

The pegasus snickered, watching closely as Twilight’s cock bounced up and own, growing harder and longer as she did. “Yeah Twi?”

“What do you think you were doing?” Twilight yelled.

“Sucking you off, and by the looks of it you were enjoying it.” Rainbow Dash smirked, leaning a little closer and rubbing a hand down Twilight’s fabric covered length. “Didn't you big guy?”

“R-rainbow!” Twilight pushed her back, though it was so lightly that Rainbow Dash only moved out of politeness. “You can't just go doing something like that without first asking somepony!”

“Oh come on, you loved it. Besides.” She smirked, leaning closer and gently nuzzling her length. “I knew how you were looking at me, staring at my breasts whenever you thought I wasn't paying attention.”

“I-I.” Twilight stuttered weakly.

“Just admit it Twilight, you loved feeling your cock ram down my throat.” The pegasus wrapped her hands around Twilight’s length and pumped her cock through the fabric of her skirt. “You want to feel it again, and this time you don't want to stop until you’ve unloaded every drop from those massive balls of yours.”

“I-I…” Twilight gulped, releasing her hands and placing them back at her sides and allowing Rainbow Dash unmitigated access to her cock.

Rainbow Dash snickered.“That's what I thought.”

With a deft flip of her wrists the skirt was lifted up and out of the way, allowing the pegasus to bask in the presence of Twilight’s enormity. The mere sight made Rainbow Dash weak in the knees all over again, the heat in her pussy once more growing to new and ever increasing heights of arousal. Rainbow wasn't sure if it was just Twilight’s cock but either way, she knew after she got this thing back inside her, that she wouldn't be able to go back to anything smaller than this.

Stopping only briefly to linger at the flared head of Twilight’s massive cock, Rainbow Dash wrapped her lips around the end of it. She paused for a moment, feeling her jaw adjust to feeling such a massive invader resting inside her mouth, before reaching forward, her arms barely long enough to grip Twilight’s legs. With something to hold on to now secured, Rainbow Dash took a deep breath and threw herself forward, impaling herself on Twilight’s three feet of girl cock.

Diving down quickly, Rainbow Dash could feel every last aching inch of dick slide inside, making her throat bulge in seconds and drawing out an adorable moan of pleasure from the alicorn. Rainbow Dash had bigger things in mind, namely drinking all the delicious cum she could possibly swallow.

To that end she dove down the girl’s length, eager to swallow more of her cock and only stopping when her nose bumped against Twilight’s medial ring. She blinked, having not realized just how big it was when it first surged down her throat, slightly amazed she had even managed to fit the thing inside her in the first place. It was large, easily over an inch in diameter, and something that would prove quite the challenge for the average girl.

But Rainbow Dash wasn't the average girl, and after feeling the potion’s effects she not only felt hotter, but also oddly stretchier, like her hunger had grown along with her ability to take that hunger. Giving her head a shake, the girl pulled back a few inches before breathing deep through her nose and then, with all the force she could muster, throwing herself against the cock and ramming her lips against the medial ring.

For a second it didn't seem like Rainbow Dash would be able to do it, then all at once, her jaw creaked, and her lips surged down Twilight’s cock. Nearly an entire foot of hot girl dick flew down her throat, until finally Rainbow Dash’s nose rested once more against Twilight’s sheethe, her nostrils filling with the scent of a powerful stallion.

The two girls shuddered in shared pleasure, Twilight from the pleasant sensation of tightness, and Rainbow Dash from the feeling of utter fullness granted by having such a massive peice of girl meat rammed down her throat. Not wasting any time, Rainbow Dash began to suck, while also forming a tight seal around the base of Twilight’s cock.

With ease that surprised even her, Rainbow Dash she began to massage Twilight’s dick using only her tongue and her throat muscles, earning her another throaty moan from the girl above her. Twilight’s knees went weak, her entire body shuddering as she felt her friend really start to work her cock. Although not quite a virgin, Twilight wasn't exactly experienced and there were very few ponies willing to try and take her monster of a cock, and fewer still who could. Which explained why she was so enthralled by the sensation of Rainbow Dash’s tongue lavishing her cock head in attention while her throat massaged her massive length.

Logically Twilight knew Rainbow Dash shouldn't have enough space inside her to accompany her enormous length, but right now she wasn't exactly thinking logically. It took all her will and attention just to keep from falling over and becoming completely overwhelmed by the sensations assaulting her mind. Using a hand, Twilight gripped the back of Rainbow Dash’s head, earning her a throaty moan while she held her friend down, though that wasn't exactly needed as Rainbow Dash wasn't about to move unless the library suddenly caught fire.

So overwhelmed was the girl that she couldn't even hold back the urge to cum, the sensation rapidly coming closer with all the force of a steam engine. “R-rainbow, I’m about to cum!”

“MF FF!” Rainbow Dash grunted back, attempting to command the alicorn to do it.

She wasn't sure if her message got through, but it wasn't like it mattered, as the alicorn suddenly shuddered, her balls quaking audibly as seed built inside them. Then, without warning, her cock exploded with cum, seed rocketing down her cock and erupting into the pegasus’ stomach with the force of a firehose. More and more of the potent cum exploded into her, easily filling her belly in mere seconds, yet more room seemed to remain, her stomach ballooning in size in order to contain the massive outpouring of seed.

Rainbow Dash’s eyes went wide and just as she was readying herself to pull back and yank all three feet of girl cock from her gullet, she felt it. The heat had dulled slightly, but in it's place was a hunger, one that would make her grip the alicorn’s waist with both arms, hugging her tightly and ensuring she could go nowhere.

On and on the alicorn’s orgasm went, filling the pegasus beyond what should be possible. Abs vanished, her trim features dulled as her curves bulged, her already titanic tits growing several sizes larger at the same time as her ass did as well. Her shirt, pants, bra and panties all began to strain to contain her growth, until finally in a cacophony of tearing fabric her clothes came undone and she was left nude, her garments unable to keep up with the rapid growth of her body.

Finally with one last pulse of seed she felt her friend’s cock begin to soften for the first time in several minutes. Rainbow Dash felt strange, rung out almost, as if her body had been run through the wringer and come out the other side changed. She didn't really have time to think about that too much though as Twilight had begun to pull out of her gut, her massive cock forcing her to take several steps back before finally able to pull the tip free form Rainbow Dash’s lips.

The feeling of her stomach, throat and mouth no longer being stuffed to the absolute gills with girl meat was a strange one, as she had long since grown used to the sensation of utter fullness that came with Twilight’s cock. It was as if she had been molded into a shape perfectly meant to pleasure the dominant alicorn and serve her titanic cock.

Rainbow Dash paused, only to belch so loudly that she was pretty sure the neighbors would have heard her. “Oh damn, that was good. Up top.” Rainbow Dash raised her arm, only for Twilight to sigh and roll her eyes, reluctantly high fiving the excitable girl.

“I’m glad you got your fill Rainbow Dash but we really should continue with our experiment.” Twilight pointed out, trying to stuff her now semi flacid cock under her dress, only for the massive appendage making that act a difficult one.

“Wait a second Twilight.” Rainbow Dash interrupted, grabbing Twilight’s arm and stopping her from attempting to stuff her cock back behind her dress. “Can't we just go one more time? Please?”

The alicorn seemed to think about it, looking down at Rainbow Dash’s smiling face, and then down to her friends now even more massive tits. “I err..” The alicorn’s expression became almost glazed as she stared off into space, caught in the hypnotizing depths that were Rainbow Dash’s massive breasts.

Noticing where Twilight was looking and knowing well the look on her friend’s face, Rainbow Dash gripped each of her titantic tits and hefted them up before pressing them together, ignoring the fact that they felt heavier than normal. “Like what you see?” Rainbow Dash asked coquettishly, smirking at Twilight’s distant expression.

“I…” The alicorn tried to tear herself away, turning her head and trying to take a step back. “We shouldn't, I’m too big and-”

Whatever she was about to say was cut off when Rainbow Dash grabbed her friend’s hand and placed it on her breast, squeezing it gently. The pegasus didn't even have to wait a single second to know whether or not her trick had worked, as Twilight’s cock twitched and grew another few inches, becoming harder by the second. “Go on Twilight, feel them. Squeeze them. I want you to.”

Twilight turned back to her friend, staring down at the still kneeling girl and noting just how incredibly soft her friend’s breasts were. “Wow.” The alicorn muttered softly. “Did they get even bigger, I could have sworn…”

“Shhh.” Rainbow Dash smirked, hefting her other tit up and motioning for Twilight’s other hand to join her first one. “Go on Twilight. I bet it feels even better when you grab them both.”

The alicorn nodded weekly, grabbing the girl’s breasts in both hands and kneading the soft flesh. A slow smile slowly crossed her face and Rainbow Dash watched as the girl’s orgasm grew larger by the second. At the realization that her next meal was so close at hand, the hunger that burned inside her grew ever more powerful, to the point that even the massive load still resting in her gullet felt small.

It wasn't enough, she needed more, she needed to be filled completely. She needed to become so filled with potent alicorn seed that her entire body was little more than a container for Twilight’s cum.

“So Twilight…” Rainbow Dash whispered, watching her friend molest her breasts slowly, her cock now as hard as it had been when it was plunged deep in the pegasus’ gullet. “Ready for round two yet?”

Twilight nodded slowly, taking a step back and giving her head a light shake. “I, we should probably find somewhere else a little more comfortable don't you think?”

Rainbow Dash struggled to her feet, ignoring the distinct feeling of her belly shaking as she rose. “No time, I need you inside me now.”

“Okay but…” Twilight’s mouth slammed shut as she watched Rainbow Dash turn and grip a nearby desk, bending over and exposing her slick girlhood. “That works.”

“Come on Twilight, pick a hole already and fuck me.” Rainbow Dash whined, giving her ass a shake as she looked over her shoulder at the alicorn. “You could fuck one and then the other if you really can't decide.”

“I didn't know that was even a possibility.” Twilight remarked, awkwardly shuffling forward before sighing and simply removing her dress in it's entirety. “Are you sure your ready for this Rainbow Dash? I know you managed to swallow it but it's a whole nother challenge to fit it inside your other holes.”

Rainbow Dash rolled her eyes. “Twilight, if you don't fuck me right now I am going to tell Pinkie Pie that you hate cake.”

“You wouldn't…”

“Try me.” Rainbow Dash shot back.

The pegasus had expected a good, powerful thrust, but what she had not been expecting was just how much power was behind said thrust. Her attempt to brace herself before it was a smart one, and probably saved her from the worst of it, but it didn't stop her from being rocked forward, her tits banging against the desk as the flared head of Twilight’s cock slammed into her asshole with enough force to just barely slip inside.

“Holy hell Twilight.” Rainbow Dash yelled, desperately gripping the desk.

“You asked for it.” Twilight shot back, slamming her hips forward again and again, leaving the pegasus absolutely no time to react between each titanic thrust.

At first it didn't even seem like the girl would even be able to work the head of her cock into Rainbow Dash’s tight hole, despite the tip that was inside. The girl’s cock was simply too large, too imposing, the flared head posing too much difficulty for Rainbow’s tight ring. Then she felt it, something inside her shift, causing the entire head of Twilight’s cock to slip inside and drawing a surprised gasp to the girl’s lips.

Twilight wasted no time, and eagerly thrust forward again and again, driving deeper and deeper by the second, ignoring the incredible tightness that squeezed her cock like a vice grip. With each thrust she seemed to loosen up, though whether that was from Rainbow Dash relaxing, or Twilight simply destroying the girl’s hole so completely that she couldn't even keep squeezing the dick girl’s cock was up for debate. Not like the alicorn much cared, as she wasn't trying to be nice.

Unbeknownst to her, Rainbow Dash was enjoying herself far more than she had let on, and the girl let out a deep, bestial moan of pleasure. She was beyond tight, but it was worth it, the heat was subsiding, leaving her only with the deep hunger and animalistic drive to be filled with semen. Her fingers gripped the desk, her tits and belly hanging over the side and though she couldn't see past her tits, she knew the alicorn’s cock was stretching her belly, the cock head becoming visible despite how large Rainbow Dash’s belly had grown.

Inches became feet, and with each thrust Twilight was forced to take a slight step forward, her cock slowly disappearing into Rainbow Dash’s hungry depths. Throughout it all it Twilight was surprised to feel that her friend’s ass always seemed to have more room left to fill. Each time they seemed to reach an impasse, and Twilight began to wonder if this would be it, a hard thrust seemed to fix that. In a matter of minutes Twilight was surprised once more, this time it was due to the fact that her crotch was nearly touching Rainbow’s backside, signalling that the slutty girl had managed to take every inch of her mammoth cock.

“Wow.” She muttered, staring down at the girl and wondering just how far up her friend’s back her prick had penetrated.

Rainbow Dash was in her own little world of pleasure, too fascinated by the feeling of complete and utter fullness that had captivated her mind. An orgasm she hadn't even seen coming suddenly exploded into the forefront of her mind and she nearly lost her grip on the desk from the shear power of it. “Oh fuck yeaaaaah.” She whispered, eyes rolling into the back of her head.

Twilight chuckled, noticing the way the girl’s entire body seemed to quake as she came, the feeling running down her back and ending at her legs. “Enjoying yourself Rainbow Dash?”

“You fucking know it.” Rainbow Dash shot back, only to shake her head, dismissing the cobwebs that clung to her mind. “Now hurry up and fuck me before I find someone who will.”

“Good luck with that, the only ponies with cocks as big as mine are the other princesses.” She snickered, giving Rainbow Dash’s ass a firm smack. “Which means your all mine.”

The alicorn lifted an eyebrow, noticing how her friend’s ass seemed to squeeze down a little harder when she said that. “Fuck that's hot.” Rainbow Dash whispered.

Twilight smirked, and without warning slammed their hips together, pounding Rainbow Dash’s hole with all the force the short thrust could muster. “Well slut, I’m about to give you everything you want. You better not come to regret it.”

Rainbow Dash’s response came out in a half whispered gurgle of noise that was barely audible above the sound of Twilight’s hips connecting with Rainbow Dash’s truly massive ass cheeks. The soft clap was like music to Twilight’s ears, and was almost as enjoyable as the feeling of her titanic sack against Rainbow Dash’s dripping snatch, which was in turn almost as good as feeling of Rainbow Dash’s fat ass.

The combination was a powerful one, and Twilight felt an even greater desire to utterly ruin the poor girl, her earth pony strength coming out and enabling her to push harder, thrust faster. Resulting in the room being quickly filled with the sound of the girl’s intermingled moans, the sound of flesh on flesh as well as Rainbow Dash’s cum filled belly sloshing around with every thrust. Twilight felt almost empowered by the knowledge that her seed was now sloshing around inside her friend’s belly, pushing her a little faster, a little harder.

Something that Rainbow Dash was loving every single second of, her entire being now completely focused on the feeling of her ass being utterly devastated by Twilight’s mammoth cock. There was a small part of her that knew this should be impossible, the girl’s cock was like three feet in length, and last Rainbow Dash had organs that should be in the way. That was a question for not horny Rainbow Dash, as horny Rainbow Dash did not care about this fact one bit.

It didn't take long for the girl to climb to the height of pleasure once more, the stretching, warping and sloshing being all too much for Rainbow Dash. As she cried out in wordless pleasure, she felt Twilight’s thrusts quicken and her balls begin to churn. Knowing what was coming, Rainbow Dash chose to enjoy the last few seconds as much as possible, and even while her pussy quivered and came, squirting all over the floor, she focused herself and squeezed down on the cock in her ass.

This seemed to have the effect she desires and Twilight’s already lurching thrusts became even more erratic, pulling out mere inches before slamming inside only to pause as she struggled to hold on even a moment longer. The alicorn knew it was a losing battle, and so it was that she gave up, her hands gripping Rainbow Dash’s waist tightly before throwing herself into one last powerful thrust. A thrust so powerful that she made the now curvy woman’s body shake from the shear force.

“I’m cumming!” Twilight cried, holding onto Rainbow Dash desperately, her nails digging into the other girl’s skin.

“Do it!” Rainbow Dash cried. “Fill my ass with your seed!”

With such encouragement, Twilight couldn't help but do just that, grunting as she felt her cock begin to erupt with cum, spraying the depths of Rainbow’s ass with her thick baby batter. The other girl cried out as well, gripping the desk tight enough to scratch the wood.

Load after potent load surged deep into the girl’s body, filling her so utterly that she once more began to wonder how she was going to be handle it all. Rainbow Dash considered the possibility that she wouldn't be able to take it all for maybe a half a second, before the hunger deep in her bones assured her that she could take it all, she needed it after all. She needed to be filled, to be made larger, to feel the other girl’s potent seed fill every bit of space possible.

Twilight breathed hard, looking down as her cock twitched and pumped the last few drops of cum into her friend’s ass. Rainbow Dash’s normally well muscled body was all but gone, replaced in it's entirety by a flabby, fat covered one that accentuated her assets quite a bit. As she gazed down she noticed just how big the pegasus’ ass had grown, and not only that but when she reached down and gripped her tits she noted that they were much larger than they had been only minutes ago.

“Rainbow Dash are you feeling alright?” The alicorn asked nervously.

The girl shuddered in pleasure, running one hand down her chin and neck and down to her breast, squeezing it and Twilight’s hand. “I feel fucking amazing. Don't you dare stop.”

“Are you sure? No one should be able to take that much cum in one sitting.” She remarked.

Rainbow Dash laughed haughtighly. “Ha! They obviously have never met me before.”

“Still, have you seen how big you've-” Twilight began.

“Twilight. I don't care.” Rainbow Dash interrupted, glancing over her shoulder at the alicorn. “Now you better keep fucking my ass, or switch holes. Choose quickly.”

“Uhhh.” Twilight thought about it a moment before shrugging her shoulders and pulling back, eager to complete the trifecta and fill the last of her friend’s hole. Sure she worried about possibly ruining the poor girl, but it didn't seem like Rainbow Dash cared, so why should she, right? “I’ll switch holes.”

“Good choice.”

The alicorn quickly pulled back, ripping her cock from Rainbow Dash’s ass and sighing contently as she felt the head of her cock emerge from the other girl’s cloying depths. Without waiting a second, Twilight pushed the head of her cock down with a little bit of magic, aligning it with Rainbow Dash’s pussy and thrusting forward.

With her cock still only semi hard it didn't take much to penetrate the girl, Twilight’s flaccid head pushing deep in a single thrust. This time Twilight had the additional assistance of Rainbow Dash’s natural lubricant, making the already easy penetration even easier. In only three thrusts Twilight felt their hips connect, shocking her by just how easy it was to fill the poor girl’s now stretched pussy.

Rainbow Dash shuddered, a hand squeezing her breast tightly, pinching her nipple. “That's so fucking good.” She whispered. “What are you waiting for, keep going. Oh and this time, give me all you got.”

Twilight raised an eyebrow and smirked. “Alright, though you might come to regret that.”

Rainbow Dash chuckled. “I doubt that.”

The alicorn shrugged. “We will see.”

The pegasus was about to shoot something back, but the sudden sensation of Twilight landing on her back, her naked breasts pressing against the pegasus’ back making him shudder in pleasure. The alicorn had evidently discarded the rest of her clothes, and was taking this seriously. Her hands reached down, gripping the other girl’s breasts tightly, giving her nipples a slight tweak and drawing a chuckle to the alicorn’s lips.

“You love it when I’m rough with your tits, don't you?” Twilight teased.

“I just love it when your rough, the rest is just details.” Rainbow Dash shot back, pressing her hips against Twilight’s and giving them a wiggle while squeezing down with her pussy. “Well, what are you waiting for Twilight? A written invitation?”

The alicorn grunted, both surprised and impressed by just how powerful the other girl’s kegel muscles were. Not to be outdone, Twilight continued her rough treatment of the girl’s breasts while also thrusting in and out of her pussy. Her earth pony strength coupled with her pegasus dexterity ensuring her thrusts were as powerful and as perfectly timed as ever.

In no time at all the room was filled once more with the sound of moaning and love making, with Rainbow Dash’s voice having risen a few octaves while also growing in volume. Twilight noted this but said nothing, choosing to tease the other girl when she was no longer balls deep in her pussy. Smirking to herself, Twilight leaned down and nibbled the other girl’s neck, drawing another high pitched moan from the formerly athletic girl.

Rainbow Dash shuddered, impressed by how well Twilight had taken to her demands to be ravaged, as she had expected more resistance from the bookish nerd. It didn't matter though, she would talk about such things later, when she had a moment to think and the hunger had lessened. So captivated was the girl, that she hardly even noticed the sound of her belly sloshing around audibly, her titanic stomach shaking with each and every thrust.

Unperturbed by the strange turn of events, Twilight was merely happy that her friend was in no obvious discomfort, silently vowing to figure out what had gone wrong with her substance at a later date. She had a girl to fill first, and that meant she would have to really step up her game and fuck her friend good and properly. Which started with increasing her pace and her strength, her cock slowly rehardening inside Rainbow Dash’s pussy, filling it more with each passing second.

The feeling of stretching that accompanied every thrust was beyond pleasurable, and Rainbow Dash wished she could keep feeling it forever. Though it may not have lasted as long as she liked, it did last long enough to make her finish yet again. The feeling of stretching, filling, and rough treatment her neck and nipples were getting giving her another powerful orgasm.

Her body shook, her stomach quaking and shaking, the cum within sloshing around as Rainbow Dash held onto the desk, her back arched and her hands gripping the table tightly. Even still, the girl could have sworn as though she was about to slip away at a moment’s notice, the powerful orgasm filling her limbs with a feeling of weakness. Rainbow Dash was not easily put down though and she gave her head a shake, gritting her teeth as she fought off the urge and focused on the feeling of Twilight’s cock.

There was no doubt that it was at it's full enormously length by now, yet she didn't feel the pain she assumed would have came from such an experience. It was as if she had somehow gained more depth then she had a few minutes ago, getting just enough of an age to contain the girl’s beastly appendage without difficulty without getting too loose that she could no longer felt it.

And feel it she did.

The other girl’s freakish dick was so large that her medial ring rubbed against Rainbow Dash’s clit with every thrust, her balls slapping audibly against Rainbow Dash’s mound. Everything about the other girl’s anatomy seemingly scaled up slightly above what it should be. Not like that posed any difficulty to Rainbow Dash, whose body had become more elastic then usual, though neither party truly knew that at the time.

On and on they continued to fuck like animals, with Twilight biting and nipping at Rainbow Dash’s neck as she squeezed and played with the other girl’s nipples. Rainbow Dash herself was so awash in lust that she could hardly tell what was going on, her entire existence focusing on the delicious ecstasy that came from Twilight’s perfect cock.

Time seemed to lose all meaning as the pegasus seemed to cycle between orgasming and recover at an alarming rate. She hardly even noticed Twilight’s slowing thrusts until the alicorn shuddered, breathing hotly in her friend’s ear. “I’m almost there.” She whispered.

“Do it… wait.” Rainbow Dash paused. “Are you fertile?”

Twilight chuckled. “Alicorns can choose to be fertile or not, and I assumed you didn't feel like getting knocked up.”

“Oh thank the goddess.” Rainbow Dash muttered. “In that case you better fucking fill me with cum.”

“Yes ma’am.” Twilight chuckled, and stood suddenly, releasing the death grip she had on the other girl’s breasts, already missing their tender warmth immensely.

Before Rainbow Dash had the chance to figure out what was going on she felt Twilight’s hips crash into her own, the alicorn’s balls slapping into her with enough force to make the impact audible over the sounds of their lust. The now quite curvy girl moaned, a shudder running up her spine as she felt the alicorn continue to pound her pussy with all the force she could muster. Earth pony strength once more came in handy, and Rainbow Dash found herself in a near constant fight just to not get pushed off the desk, Twilight’s thrusts making this task a difficult one.

Her thrusts were long and deep, pulling out as far as her hips would go before slamming back inside with all the force of a hammer blow. The power, the stretching, the roughness, it all culminated to become the most powerful feeling of pleasure that Rainbow Dash had ever felt in her life. Only one thing could make this even better, something she already knew was coming closer by the second.

The sound of Twilight’s now familiar grunt as her balls begin to churn with seed was a pleasant one. Prompting Rainbow Dash to relinquish the hold she had on her orgasm, the first splash of cum making her cum harder than ever before. The weakness from before returned with a vengeance but Rainbow Dash held on, barely able to keep her grip on the desk.

As more and more seed splashed into her belly Rainbow Dash once more felt her stomach stretch and distend, forced to grow larger and larger as more seed exploded inside her. Twilight seemed as relieved as Rainbow Dash was, and collapsed to her back, grunting in pleasure. “Sorry I didn't warn you Rainbow Dash.” She remarked.

The pegasus merely grunted in return, struggling to keep herself from falling to the ground. “I’m having trouble staying up here you better-”

But it was too late, Rainbow Dash’s hands gave out and she slipped from the desk, falling all of half an inch before her now gigantic belly touched the ground, sloshing around when it did. The pair both remained stock still, confused by the sudden turn of events, that was until Twilight stood back up and realized what had happened.

“Rainbow Dash, your enormous.” She pointed out in shock.

The pegasus blinked, looking down past her tits, that were now so large that she wasn't even sure if there was even a cup size that could contain such massive mammaries, and towards her belly. “Wow you weren't kidding.” Rainbow Dash replied, looking down at her stomach which now rested firmly on the ground.

“I guess there are some kinks with our experiment after all.” Twilight remarked offhandedly.

“You think?”

“Oh don't be like that I’m sure there is a way to fix all this.” Twilight shrugged. “We've dealt with plenty of magical and chemical accidents in the past, this is nothing.”

Rainbow Dash chuckled, turning and looking over her shoulder at the alicorn. “Who said this is even a problem.”

“B-but you can't even stand never mind fly.” Twilight pointed out.

“That's a problem for future Rainbow Dash, horny Rainbow Dash wants more dick.” The pegasus smirked, licking her lips and eying the alicorn hungrily. “So. What do you say princess? Ready for round four?”

Twilight’s ears perked up and she found a smile crawling across her lips. “That does sound nice…”

Rainbow Dash chuckled. “So hot stuff, which hole are you taking this time?”

Twilight smirked. “I’ll take-”

Author's Note

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