Expand Rare

by Dark_Star777

Rating: mature
Tags: Sex, Twilight Sparkle, Random, My Little Pony: Friendship is Magic, Anthro, Original Character, Porn, Fetish, Spike, Comedy, Rarity
Length: 3409

A fairly shameless smut story, featuring Rarity reaching dangerous levels of curves, and a super hung Twilight testing the limits

Rarity was always quite the beautiful mare. Not too lean, not too much body fat, or at least, not in the wrong places. She worked hard to receive a body such as hers, but a call from Twilight may just lead to her figure getting that much better. She just hopes that the Princess of Friendship can keep her paws off her long enough to get a word in edgewise.

This story contains: Breast expansion, ass expansion, slight height increase, bodysuits, futa-Twilight, and lots and lots of shameless fucking.

Published 2020-06-29 23:10:00 UTC
Last updated 2020-06-29 23:10:00 UTC

Dangerous Curves Ahead

Another day in Ponyville, another day working hard. Today, we join a true work of art as she works out at the local gym. Rarity, a truly pristine beauty in her own right, but not one to go without a proper workout. Well, it would be proper if she spent more time doing it instead of trying to work on dresses. Sometimes, the orders got filled up, and she was left with little time to maintain the figure she'd worked so hard to perfect. Of course, she was still one for fashion, and worked to maintain such an image, even when sweating and working out.

She wore a tight black sports bra that maintained to contain her perky C-cup breasts, working to make sure they stayed perky and lacked sag. Magic was certainly nice to prevent things such as that, but being a perfectionist such as Rarity meant having to make sure she was natural. Going lower, we see the specially designed black-legged yoga pants the fashion pony wore, with the sections around her crotch being a lovely teal color. Her lower body looked just as lovely as her upper body, albeit with more weight hanging behind her. Not fat, by any definition, but wide and curvy enough to get the attention of many stallions throughout the years.

"Keep going, marshmallow, swimsuit season is right around the corner!" barked one Slipstream, Rarity's personal trainer. She was a cyan pegasus mare with mint-green hair, tied using white hair ornaments into two framed locks beside her face, and a proper ponytail in the back. Even her tail was partially wrapped, since it would be too long to walk with otherwise. She wore a black sports bra and matching booty shorts, both of which had gold trim to them. Lastly, was her fairly toned figure, clearly lacking in curves, but she made up for it with enthusiasm and motivation.

"Toughen up, creampuff!" Slipstream grinned, Rarity grunting to herself as she continued doing sit-up after sit-up. If she didn't know any better, she'd assume that the pegasus enjoyed barking orders towards the other mare. "Go, go, go!" Slipstream continued, the fashion mare just huffing and puffing as she finished the last of her reps and then lied back on the bench with her lungs burning.

"Good hustle, Rares, keep it up!" Slipstream smiled, handing the fashion mare a bottle of ice cold water. As soon as Rarity could properly lean up, she found herself grasping for the bottle and chugging down all the refreshment she could, sweat glowing across her entire body as she worried internally about the condition of her coat. Still, she did appreciation the extra motivation. The sound of her cell phone ringing then caught her attention though, bringing her phone over towards her via magic.

"Hello?" Rarity greeted cheerfully, wiping some sweat from her brow.

'Hey, Rarity, are you free right now? I've got something I need your help with' Twilight Sparkle greeted from the other side.

"Well, yes, actually. I believe I'm done with my workout routine right now....Right?" Rarity asked a moment, getting a thumbs-up from the pegasus. "Yes, I'm done with my workout now" Rarity smiled.

'Good, need you to come on by the lab right away' Twilight had told her friend.

"Right away? But I haven't even showered yet! I'm glowing all over right now" Rarity complained. Twilight and her need for things to happen around her. You'd think she would learn to take things easy and wait every now and again.

'There's a shower here you can use, I just need you to come and test something while it's still fresh in my mind' Twilight answered as Rarity just rolled her eyes and pinched the bridge of her muzzle.

"Very well, I'll be right over" Rarity answered, hearing what sounded like cheering from the other side of the phone. She soon hung up and bid Slipstream farewell, reassuring her she'd be back around the same time tomorrow.

Rarity arrived at Twilight's castle relatively quickly, adjusting her top to make sure it was still snug. After stepping inside the castle, down a few hallways, and then down a staircase leading into the basement, Rarity had found Twilight seeming to be welding something. Of course, rather than using a proper welding torch, she seemed to be using a magic-infused finger to be doing the burning. Rarity magically poked her shoulder and found her turn almost right away, showing off her mane being messy and her welding mask on tight.

"Hey, Rarity, just in time! I was just putting some finishing touches on my newest invention" Twilight smiled peacefully, pulling what looked like a red, rubber, bodysuit out from her worktable, her wings flaring out rather happily. Rarity looked at it with some confusion, blinking her eyes twice as she tried to figure out just what she seemed so excited about.

"Um....It's quite....fetching, Twilight. Now, where did you say the shower was again?" Rarity giggled, soon being met with magic stripping her naked and dropping hot water and soap on her body, followed by gale-force winds blowing her dry, all within mere moments of one another. She blinked awkwardly, trying desperately to regain her balance as she could feel just how distorted her hair was from the wind.

"You know, Twilight, I hate when you do that" Rarity deadpanned, covering her crotch and chest with her arms as Twilight just giggled sheepishly.

"Sorry, Rarity, I'm just a little bit excited to finally have finished this. It took at least four days straight working, and it was driving me crazy until then" Twilight giggled to herself as she stood up, walking over towards her fashion-minded friend as the latter had summoned a brush for her mane.

"I noticed. Still, you could stand to be a little bit less sudden about your magic and such" Rarity answered, still curious about the bodysuit. "As for that, what exactly is supposed to be so important about it?" she then asked.

"It's just something I thought would prove useful to the more....curve-challenged mares in the world. I don't think I need to remind you how many conversations I've had with Rainbow Dash when she's drunk" Twilight had then answered, thinking back to last week and a bizarre phone call from a drunken Dash.

"Yes, she certainly does have a....way with expressing her figure" Rarity then answered, always being concerned with how Rainbow Dash wanted larger breasts or a more shapely rear.

"Well, it's because of that that I started working on this. This suit should be capable of expanding the figures of mares of wear it" Twilight then mused, looking over the suit carefully and then handing it to Rarity.

"And you needed me to test it?" Rarity asked.

"Didn't you say you envied Fluttershy's breasts for being so massive?" Twilight then asked.

"I said no such thing!" Rarity answered, her face burning up in embarassment as she denied something she actually did say a few years back. To think, Twilight would actually remember such an odd conversation she, Twilight, and Pinkie Pie had during one girl's night out.

"I'm entirely certain that you did, Rarity" Twilight mused, keeping a straight face as always.

"Be that as it may, I'm not sure I want to alter a figure that I've been working hard on. It cheapens the entire point of working out in the first place" Rarity then argued, believing that such a shortcut would've likely meant she wasted a massive amount of time for nothing.

"Don't worry, I should be able to reverse the process afterwards" Twilight then mused.

"Should be?" Rarity gulped.

"Don't worry about it, this isn't going to be anything like the last experiment" Twilight chuckled, giving Rarity some bad flashbacks of the last experiment. She still couldn't get the smell taken care of. "Please, just trust me on this" Twilight then mused, putting on her cute eyes for a moment as Rarity just sighed.

"Fine, but this had better not ruin my figure" Rarity pinched the bridge of her muzzle, easing herself into the suit as carefully as she could. Twilight answered with a big, adorable smile as she got what she had wanted.

Rarity squeezed the red rubber over her plump rump carefully, thankful that the fabric was as stretchy as it was. If it wasn't, it would've easily torn while trying to contain such curves of hers. Had she not known better, she could swear that Twilight was watching her, or rather, that she was staring at the fabric stretching across the expanse of her booty. Although, to be fair, she couldn't blame her. Rarity knew fully well just how good she looked, and a part of her did enjoy the occasional staring, but sometimes, it felt a little bit awkward to be stared it when in a lab. She pulled her tail through the hole in the suit and stretched the fabric carefully before pulling on the arms of it.

While she worked, Twilight was hard at work observing with every fiber of her being, watching all that red rubber cling tightly to Rarity's body, and when she began working on the chest of it, it gave the alicorn a slight bulge in her groin, forcing her to have to think of very un-sexy things to make sure she didn't lose focus. She needed to make sure that this worked without a hitch.

With one final snap, Rarity was fully dressed and started to observe herself in the conveniently located mirror just beside her. She had to admit, the suit did look quite fetching on her, accentuating her curves very well as is. Seeing the sights of her nipples through the top and even seeing quite the outline of her cameltoe, it somehow made her feel more exposed than if she were actually naked. The suit covered everything up to her neck, and yet somehow, breathed surprisingly well, and she began taking a few experimental steps around, Twilight eyeing every single movement to make sure that Rarity didn't accidentally tear it.

"Okay, I'm dressed. Now what?" Rarity had asked, Twilight not really paying attention for a moment. "Twilight?" she asked again, trying to get an answer. She had point a hand on her hip and put on an annoyed little pout, watching carefully how Twilight seemed to be in her own little world, again. "Twilight, darling!" she raised her voice, Twilight doing a double-take as she came back down to Equestia.

"Oh, sorry, I was just taking note of the....curves" Twilight answered, sweating a little bit as she adjusted her posture, her bulge actually getting a little bit more noticeable. Twilight followed Rarity's eyes and covered her crotch a little bit, blushing profusely. ".....Sorry" she squeaked adorably.

"Please, darling, don't tell me that this was done just to get me in some fetish suit?" Rarity sighed, looking at the other mare with a very judgmental look.

"I promise you, this boner of mine is just a coincidence. Science is my main fetish" Twilight answered with a very professional tone and stance. "A-anyway, the next step is funneling magic into the suit. It's supposed to be programmed to immediately expand your body in your breasts, butt, hips, and thighs. I just need to make sure it does what it's supposed to, so be ready. You may feel a tingle, but it'll turn to pleasure soon enough" Twilight then continued as she had her curvy friend stand in a specifically designated area and then moved off a safe distance before then flaring her horn in her aura, channeling it onto the suit as Rarity already started blushing from the warm sensation building up between her legs.

"Try to avoid squirming around too much, I don't want anything else to happen" Twilight instructed as Rarity nodded, scrunching her eyes shut as she felt the suit fizzling about on her body. She almost felt as though someone was pinching her nipples and her clit at the same time, moaning out lewdly as she felt the suit do its work. She peered down and watched as her breasts started growing larger, rounder, thicker. Her ass and thighs went through the same thing not long after, growing out rounder as the rubber stretched out, sounds of squeaking as she could hardly contain her voice.

Twilight jotted down more notes as she watched the event take place, watching as Rarity's body grew thick in all the right places. She'd say that Rarity was growing 'extra thicc', had she not had a severe hatred of memes and meme culture. Still, it was something else to see her body grow out even further. The fashion mare had already outgrown her own curves by quite a bit, and it wouldn't take that much longer for her to get to Fluttershy's level as well.

Rarity could hardly contain her voice as she felt an orgasm approaching, spreading her legs out as her thighs thickened anyway, her head jerking back as she let out a lewd moan that somehow echoed, dropping to her knees as she panted heavily, Twilight immediately stopping the magic and approaching her close friend with a worried look on her face.

"Are you alright?" Twilight had asked her, only for the unicorn to immediately pounce upon her, pinning her down to the ground and making out with her furiously. Twilight let out a surprised little gasp as she felt moisture dripping from Rarity, and her tongue swishing about inside her mouth.

"That was incredible, Twilight" Rarity quickly said, overwhelmed with feelings of lust and need as she kept kissing all over Twilight's face and neck, with the alicorn desperately trying to escape, but to no avail. Rarity soon leaned up, smothering Twilight underneath her massive E-cup rack as she was licking her horn, suckling it, tasting it and hearing the lewd noises from Twilight rewarding her.

"Oooh, Rarit-TY!" Twilight moaned out as she felt Rarity giving her one helluva good hornjob, practically drowning under red rubber as she couldn't help her self and grabbed hold of the heavy chest globes, delighted to hear that Rarity could still feel them based on her immediate moaning. It seemed as though the expansion caused greater sensitivity in her breasts. Twilight could only continue to grab hold of them, making sure that she had a good grip on them. She was a little worried about the sounds of tearing, but she felt slightly better knowing it was just her cock ripping through her jeans. Better than worrying about Rarity's suit tearing.

Speaking of, Rarity felt herself all but get jabbed by the feeling of purple horsecock poking into her thighs, stopping her hornjob and then immediately spotting the other horn. 22 inches long, and 3 inches thick, Rarity immediately began going lower, until eventually, she grabbed hold of Twilight's cock and started deepthroating it as best as she could. Twilight's eyes rolled back in her head as she felt Rarity's incredible throat muscles massaging every last inch of her cock, even feeling the rubber fabric massaging her swollen balls just below.

"Rarity, you feel amazing!" Twilight moaned out, her voice getting higher and higher pitched as she struggled to contain her moaning. She worried about others hearing her, but knew that the soundproofing was installed and prepared for just such an occasion. Spike and Starlight made it VERY clear that she had inherited the Royal Canterlot Voice, and had little control of it during the act. That line of thought would have to wait for a later moment though as she felt massive, soft, firm, white tiddies massaging around her cockflesh.

"Oh, oh, oh, CELESTIA!" Twilight screamed out as she immediately started blasting cum, unable to contain herself as Rarity used her massive tits on her. She felt the semen explode out of her cock as Rarity seemed to have some trouble keeping her breath. After a solid minute, Twilight peered an eye open to find Rarity having more white on her than she remembered, most of it dripping down her face and the suit. Rarity didn't even hesitate as she started carefully taking off the bodysuit, peeling it off and watching gravity affect her new assets.

Her breasts were utterly massive now, and her ass hung out way further than it did before. Her thighs looked thicker than any other pony's Twilight had ever seen before, not even the other princesses had curves quite like this. Well, Celestia did, but that was just an unfair comparison. Before Twilight even knew it though, she could feel her cock head being massaged by something hot and wet, soon looking to see Rarity rubbing her stallionhood between her thighs, the gap being enough that she couldn't even squeeze her legs completely together anymore. The hungry look in her eyes didn't help, and Twilight felt a little bit worried at the predatory gaze squarely focused on her.

"I need this, NOW!" Rarity announced, her voice husky and powerful, and Twilight couldn't help but feel her cock immediately fill up with blood once again. Rarity greatly enjoyed feeling it harden into diamond and then aimed it for her pussy, thrusting it inside herself as she towered over Twilight for the time being, bouncing her mighty hips above the other mare as Twilight let her do the work. Rarity's hot, tight fuckhole was beyond anything else she had ever felt before, and it almost seemed like a dream with how the fashionista was riding her.

Rarity and Twilight locked fingers and moaned out together joyfully, the wet sounds of flesh slapping against eachother echoing lewdly throughout the lab. Twilight's eyes observed as Rarity bounced upon her, her breasts bouncing harder than the rest of her. She could even see Rarity's ass cheeks bouncing about as she rode on top of her pole. Little strands of her earlier cum dripped off of Rarity's mane and face, giving her an even dirtier look that only further hardened Twilight as she felt her continue.

After enough time, Twilight immediately jerked and felt herself cumming again, Rarity moaning out as she felt herself cumming as well. She leaned over and locked lips with Twilight once more as she felt her tunnel of love flooding with hot, white, goo. By the time she stopped cumming, Twilight could only agonize over the strained feeling of her balls, carefully reaching down and rubbing them as they felt so empty, Rarity draining her completely as her cock softened, popping out of the fashionista as cum started flowing out of her like a lewd waterfall.

"Rarity.....that was....." Twilight panted carefully, having a hard time breathing with the weight of giant white tits pressing down on her. Rarity smiled and peered an eye open, giggling to herself happily.

"Perfect. Absolutely....perfect, darling" Rarity huffed as she forced herself up on off Twilight, lying down beside her as the two tried to catch their breath.

"I'd say the experiment was a rousing success, too" Twilight smiled, feeling the satisfaction of a job well done. Rarity couldn't help but smile as well, though she did have a hard time getting adjusted to her own breasts being so massive.

"In that case, can you maybe...deflate these? As beautiful as they are, I do think I was better off before" Rarity then asked, Twilight's horn carefully flaring up as sounds of air escaping a balloon could be heard. Rarity's breasts soon started returning to their previous shape as before, which soon spread throughout the rest of her body as well. Of course, by the time Twilight finished, Rarity's hourglass still had more sand in it than before, but at least it was more subtle, with a few inches added to her hips and a solid cup size bigger than before.

"Hey, Twilight, we were about to order pizza and wondered what you...." Spike's voice suddenly called out as he peered down into the lab, his eyes wide and his face flabbergasted at the sheer state of the lab. "Oh, I am NOT cleaning this up, Twilight!" he huffed angrily, not even mad to see Rarity naked and messy all over. Twilight and Rarity couldn't help themselves and laughed heartily as his face, slowly rising up and getting ready to clean up.

The End

Author's Note

Well, there's an idea that kinda took a while to get on paper....on laptop, whatever. Just shut up and enjoy the lewd horse smut.