Rainbow Dash fidgeted where she stood, a draft in the castle basement sending a chill down her naked body. She normally wouldn’t have had a problem with this, far from it in fact, as she was confident in her looks. Her lithe, athletic body, her small bust, her thin legs, they were all a part of what made her awesome.
At least, whenever she wasn’t in the room. Her master. Her owner. The one whose cock she served loyally… Or was supposed to. In fact, with what she’d been finding out ever since she began dating, and especially when they started fucking, had thrown so many things out of whack. Heck, she had even agreed excitedly last week to let consent be not a thing between them so Twilight could surprise fuck her as rough and as brutally as she wanted, whenever she wanted.
It made Rainbow feel like less. Like the small doll that so much of her found itself wanting to be so often, and it was… honestly terrifying. That was what had led to today. Rainbow had cried the last time that Twilight had come for a midnight visit, having had her ass almost ripped in two by Twilight expanding her alicorn cock while it was inside of her.
She had liked it though. She had cum. She had also cried though, and Twilight said she wouldn’t do that to her. That she wouldn’t actually traumatize her.
And now Twilight said that she could fix the problem today. To make it so this never hurt her like that again.
Twilight finally walked into the basement, her tail flicking back and forth behind her, dusting the steps that led down to the dimly lit room. The young bookworm, usually so proper and reserved now had a wide smile on her face, and only a lab coat to cover her body. Just the sight of her mistress sent shivers down Rainbow’s spine, but she also felt the pang of fear that she wanted so desperately gone.
Twilight had a far more lewd body than Rainbow, supposedly having been gifted to her by the only mare she called mistress: Celestia. Her own breasts shook and bounced with each step, swaying from side to side. Their mass jiggled and squished against itself, drawing Rainbow’s eyes to them. Saliva began to build in her mouth as she looked at the pointed, purple nipples, knowing their taste all too well. Knowing how firm they could be against her teeth, and how many times she had been almost unable to breathe because of being forced to worship them.
Twilight’s thighs were more plump than hers, though her ass was still fairly lacking, despite how many hayburgers she would normally eat. Before that joke would get her to fume, but nowadays… Nowadays it would lead to an hour of Rainbow having to force her tongue deep inside Twilight’s anus. She would have to taste whatever condition it was in, which was usually fairly clean with how much the alicorn liked anal, for as long as her jaw muscles would keep working, only able to smell her ass as she kneeled behind her mistress.
Of course, she would normally do one other thing when she ate her out like that. She would show her appreciation to the large cock all alicorns had. The third leg that showed them as princess and king. Twilight’s was almost halfway down to her knee, a hard feat after her growth spurt, and almost as thick as her arm, which had made fisting training all the easier for when Rainbow had begun that. It swayed like her breasts, though right now it wasn’t nearly as perky or stiff as they were. No, Twilight used her will to make sure that only off of her slave’s body did she get hard, and she never masturbated anymore. Rainbow couldn’t tell anypony how many hours she had spent knelt around her, stroking, sucking, and fucking that giant cock of hers for the past two months.
She just knew that it was her religion, just like all of Twilight was, and she really hoped that her god would be able to fix the problem she had tonight.
Twilight smiled at Rainbow, staring deep into her eyes, her purple pools reaching deep into Rainbow’s soul. It wasn’t the first time they’d been like this. Naked, questioning, scared. Last time, it had been for the first time Rainbow would take commands, and just like that, her eyes told Twilight the answer. Gave her the consent she was looking for, and her prick shivered and rose a little in excitement.
Twilight nodded, stepping back as her lips closed around her smile, and her horn began to glow. Rainbow could feel the magic begin to enter her, and she fidgeted again. At least, until Twilight snapped, “Still!” She then began to circle the athletic pegasus, whispering in her normal, cold tone, “I won’t ever reverse this. If I ever find out that you got somepony else to reverse this, I will make sure you don’t have enough willpower to do it a second time. You will be a slave, nothing more, after what I do, and nothing but a little doll if you ever disobey it. Of course,” her tail flicking up, a metal band on the end of it practically whipping Rainbow’s ass, “you probably like hearing that, you filthy, fucking slut.”
Rainbow kept quiet, trying to keep still even as her body continued shivering. She was under Twilight’s gaze, naked, but she was standing. That wasn’t how this was done. That wasn’t her place. Those were the thoughts she liked to say, but a part of her always resisted.
She swallowed hard, beginning to sweat from the exertion in her mind as her hands came down to her thighs. They felt… softer than normal. Yeah… They felt like they had a little fat even! That wasn’t right, and she looked down only for her eyes to widen. Twilight’s magic was honestly working quite fast, as her normally small, almost flat chest was now the size of oranges, and her thighs had almost closed any gap that used to be there. “T-Twilight! What’s going on? What sort of-”
Smack!
Rainbow jumped as her mistress’s hand slammed into her rump, sinking into the now far more tender flesh. She could feel that it felt good. No, not just good, but better than it was supposed to, and Rainbow let out a small moan as Twilight’s hot breath beat against her neck. “If you thought I would only take away that silly, mental block that’s stopping you from being the slut you are, then you’re an even bigger idiot than I ever gave you credit for. I mean, before now stallions would overlook you, so when I had you ride my cock in public, they didn’t see your blushing face. Now though…”
Twilight’s hand moved slowly, and Rainbow could feel her magic coursing through her with each moment, pumping ever faster now that the two were in contact. Now that her mistress held her. It only got worse as Twilight’s fingers came around Rainbow’s breast. It fit perfectly in her hand for now, and Rainbow could even see the soft flesh give into her mistress’s small, delicate fingers as Twilight licked Rainbow’s neck. It all sent lightning down her spine, and she could feel her pussy begin to warm up to it all. Want what was coming. Want what Twilight would do to her.
Want to be the little whore that never wore clothes or said no to a cock.
Rainbow blinked as she heard the line in her mind. It had almost slipped by with the rest. Slipped in with the rest of this new side of Rainbow but… Was this Twilight’s doing? Was she warping her mind? It would get rid of the block, but…
Twilight didn’t leave Rainbow in mystery very long. She spoke breathlessly as she ground against her pet. Her throbbing cock shook against Rainbow’s slowly expanding thighs, tightening around the thick member. Rainbow could feel its veins, and the fact that it was only inches away from her pussy. Inches away from the hole that her mistress so rarely used.
“Do you like it? Like me bringing out the whore in you? The whore I always saw? The whore that puts on those shorts that might as well show off your pussy? The whore that would walk around the locker rooms naked?
The whore that let some bookworm fuck her in front of her best friend?”
Rainbow p… She should have paled at that. It was her response every other time to the reminder of one of the most shameful moments of her life. Sure, Fluttershy had forgiven her, but getting seen riding Twilight’s cock, getting blamed by Twilight for being the one with idea, and… And not being able to stop even as Fluttershy slammed her front door shut until Twilight came… It was all so humiliating for Rainbow.
And now her mind responded with: I wish that Fluttershy had joined that day and made me fuck her too.
Rainbow blushed at the thoughts, but Twilight didn’t stop. Instead, her breasts continued to expand, slowly growing over Twilight’s grasp. They buried the small digits in their increasing size, and Rainbow could feel their weight. The slowly growing pressure on her spine. The fact that they were slowly filling with something while they slowly sagged lower on her. No longer were they glued tight to her chest, but now hung down to her stomach, having become almost twice the size of her head and she could feel the milk swaying inside of them.
They… They were too big. Rainbow knew this would slow her down, just like Fluttershy’s did. She… She couldn’t continue being a Wonderbolt like this. She would still be fast, but to do her old tricks… No, these would get in the way without some serious help.
And Twilight, not for the first time in their relationship, whispered in her ear after reading her mind, “I can get that help. I can make those enchantments so my pet can fly while a portal lets me fuck her in the middle of a show. How would that feel? Knowing that if you failed, the only explanation would be to show the reporters my seed in your pussy?”
Rainbow felt her body shiver from the idea, her pussy now beginning to leak as she imagined spreading her legs for a camera. Of all of Equestria seeing the whore pussy that they called an Element of Harmony. It excited her. It made her want to fly naked for the cameras, before letting Soarin fucking her from the front while Twilight used her favorite little hole.
And then it terrified her. Of losing her image and of the embarrassment. Everything Twilight had done to help her feel like this, to drag this side of her up was gone, and the weight of her thoughts now hit her. It left her cold. Scared.
It left her knowing that without them… Without them…
Twilight’s voice came into her ear, now scared instead of the dominant, cold steel that she normally used while they were naked as she whispered, “If I go any farther… I don’t know if I’ll be able to go back. It will be permanent without possibly years of research, so I need to know from you. What… What choice do you want to make? Because just like how I can make this part stronger, I… I could erase it. Make you never crave it anymore.”
Rainbow was silent. She knew what not having this would do. It would make her be able to be the eternally confident tomboy she had been. She would bow to nopony. She would be as amazing as she ever was, without ever letting someone call her slut because she liked it. Never letting a comment like how much of a whore she probably was slide.
But it would mean losing the one pony she had ever fucked, and she knew that. The one pony who knew better than anypony else how loyal she was, and so she reached back, gripping Twilight’s hand as she turned to her. “Mistress, you already know you don’t need permission.”
Twilight shivered as her wide smile came back, before she pulled Rainbow close, and pressed her lips to her lover’s. The shift was painless, and almost instant now that all the framework had been put in place. It just needed to be sealed into Rainbow’s brain, and the athletic mare moaned in Twilight’s mouth as her tongue tried to wrap around her mistress’s.
However, cute little kisses weren’t Twilight’s style. At least, not on these lips as she pushed Rainbow away, before her magic slammed into her slave. It swept Rainbow off her feet, crashing her to the ground. Rainbow yelped in pain, but it was translated straight to pleasure by her pussy, made only stronger as her breasts ground against the rough, crystal floor below her. They were sensitive, raw, and she shrieked as more of her own arousal dripped from her pussy from the rough treatment.
Rainbow tried to stand up, to get her breasts off of the floor, but Twilight’s magic just forced her down, pinning her to the ground. Her breasts at least were still against the floor, and she let out a sigh of relief at that. Unfortunately, that was enough to give Twilight ideas as her cock began to rub against Rainbow’s ass.
“Don’t worry, my little whore. I won’t let your newly gained assets be ignored? How about a little… friction?”
Rainbow tried figuring out what she meant, expecting it to mean that she would get her body scraped against the ground as she was fucked in the ass like normal. Twilight didn’t like normal though. She thought that if she didn’t try something special each time, that sex would become boring, or that she’d never be able to try all of the ideas in her mind.
So, instead of just sticking it into her, Rainbow felt the crystal beneath her breasts give way, melting around them as her nipples and heavy sacks sank into the ground, forcing her face onto the ground. She tried pushing herself up again, and without Twilight’s magic pinning her, she found she could.
However, she still couldn’t move, not without trying to yank her breasts off. She looked down in faux horror, her body quivering from what she began to feel.
Vibrations. Constant vibrations on every inch of her large, sensitive breasts that were encased in crystal that now shook around them. It was at a low frequency, meaning that it only stimulated Rainbow so much. She knew she should have expected that, but… But it was torture. She couldn’t cum like this, and she couldn’t reach back to touch herself to fix the problem.
All she could do was do what came naturally to her, and that was to, for the first time without prompting, look back at Twilight and beg, “P-Please, my mistress, f-fuck this slut’s ass so she can cum. She needs to. She desperately needs to and will do everything she must, but please let her cum!”
Twilight only smiled though, breaking her habit of usually torturing her slave for at least ten minutes until Rainbow was almost at the point of mentally breaking to actually start fucking her, and pushed the large, flared tip of her cock to the tiny, permanently tightened asshole of her pet. “No, you’ve done enough. Now, enjoy worshipping the cock that you always will.”
Rainbow panted, her eyes wide as she lost all sense of composure. Feeling her mistress there was too much for her now, and Twilight could see that she would need to be trained to have more modesty again. After all, it wasn’t fun to rape something that immediately acted like she liked it. That just ruined some of the game, and especially the after care.
Tonight though, that didn’t matter. Her slave had already given her plenty, and she plunged her hips forward, needing release herself at this point as she forced every inch inside of Rainbow. It was a long, hard process, as her magics made it so that her slave was always just a little too small for even her default size, and Rainbow howled in pleasure from it. From her pussy, arousal gushed like a fountain, and it was all ecstacy to Twilight’s ears. All what she had been building up to for the week that she had been preparing the spell.
Not that she just let it end there. She was no one pump chump, and once she hilted her slave once, the real fun could begin. She was relentless against her slave’s ass, just as always, pounding it as hard and fast as she could, with her speed only growing more as she managed to stretch Rainbow out bit by bit, all evidence of which would be gone in an hour.
Rainbow didn’t mind though as her eyes rolled back, tears streaming down her face by all of it. She agreed that the training would be needed, but all of this was fresh to her. Having a mind that revelled in this sort of torture, instead of just fancied it. Having a desire to want Twilight’s cock to be as big as her someday, rather than only maybe her arm. And, of course, to want nothing else in life than this cock fucking her every moment of the day and let everypony else know how much she’d take any other cock too like the slut that her mistress called her.
And of course, there was more to it then that for Twilight to be her mistress. Any stallion could fuck her, sure, but Twilight degraded her like nopony else. She had no fear about Rainbow’s pride or anything like that. In fact, she wasn’t sure if she broke her body even, as with each thrust into her ass, Rainbow thought her breasts were going to be torn off, before being allowed to rest as the vibrations right on the tip of her nipple grew stronger and stronger with each thrust too, making the stimulation on her entire body grow all the stronger.
And finally, there was the one part of her that was ‘neglected’. That wasn’t touched by her mistress, because slaves didn’t get fucked there. They were nothing but tight assholes after all most of the time, so why shouldn’t it get loosened when they were put in their place. Her pussy didn’t mind it though. Rainbow couldn’t fathom dealing with all of this while her insides tightened into a permanent knot as she couldn’t stop cumming. Even as whole minutes passed, she couldn’t stop. It was all simply too much as her mind threatened to black out. It was all so close to the end though, and Rainbow could feel it.
Unlike with the change to this new form of Rainbow though, Twilight didn’t stop. She only paused as she pulled out one more time, her cock growing at Rainbow’s entrance, her tip not letting the tight mare know what was to come.
As Twilight pushed in though, she came. She didn’t just cum though. As Rainbow felt her mistress’s cum slam into her stomach, extending it, her eyes rolled back from the pain. It felt like she was being split in two, just like the night that had led to this day.
Today though, she pushed back, helping as her ass gobbled up more and more of Twilight’s engorged cock, forcing out more and more of her cum as she even tried yanking herself up from the crystal just to get more. Not that she could with her slowly growing stomach pushing her away from the ground and permanently pulling at her giant tits.
It all came with the final push though. With how Twilight’s balls smacked into her slave’s thighs as one last stream of cum poured into Rainbow. This was too much for Rainbow’s pressured stomach though, and she could feel it come up.
And she was all too happy to taste her mistress’s cum as it began to spill out of her nose and mouth, finally putting Rainbow to bed as her eyes rolled back the last bit they needed to and her body collapsed.
Twilight merely laid down next to her slave, freeing her from the crystal and pulling her in tight. She would need to do more to perfect her Rainbow, but this was a good first step, and she wanted to be here for when she woke up so her slave knew that she would be there for this.
And even a massive slut like Rainbow resisted sucking her master off so they could cuddle like this when she woke up.