Butt

by AzureDreamer

Rating: mature
Tags: Changelings, Porn, Fetish, Comedy, Sex, Anthro, My Little Pony: Friendship is Magic, Rainbow Dash, Romance
Length: 8819

A story of unconventional love between a mare and her magical talking butt.

Rainbow Dash doesn't know a lot about changelings. She knows that a hive of them tried to invade Canterlot. She knows that they feed off of emotions. She knows that they can disguise themselves as anypony. And she knows that, when she finds one alone and starving in the Everfree forest, helping it is the right thing to do, as much as she doesn't want to admit it.

After feeding off of Dash's conflicted emotions enough to regain consciousness, the changeling introduces herself as Butt. And, in a show of gratitude for saving her life, she offers to back Dash up.

WARNING! CONTAINS ANTHROS, FUTA, AMAZONS, GROWTH, VARIOUS TYPES OF EXPANSION, MERGING, AND PROBABLY A BUNCH OF OTHER WEIRD STUFF

Cover art by airship-king, colours by 09hankris!

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Published 2016-04-30 18:10:01 UTC
Last updated 2017-09-13 19:47:21 UTC

Buttman Begins

Rainbow Dash stood over her couch, frowning down. Her hands, balled into fists, were placed firmly on her boyish hips, and her feet were exactly shoulder width apart. Her physical display of mild irritation with her situation was carefully calculated, though she wasn't entirely sure whether she was more irritated at the unconscious changeling on her couch, or at herself for bringing it here in the first place. "You'd better be grateful once you wake up." If you wake up, she mentally corrected herself. “I could have just left you in the Everfree Forest, you know,” she lied. “I'll bet no one would have objected at all.” She grunted, absentmindedly kicking the air in yet another carefully calculated display of irritation. “Or turned you over to Twilight. I bet she'd love to be able to dissect you, see what makes Changelings tick,” she lied again.

The changeling remained mostly motionless, the agonizingly slow rise and fall of its chest the only sign that it wasn't dead. Rainbow Dash groaned, kicking the air again. She really shouldn't have taken it home. With the events at the Royal Wedding still fresh in her memory – in everyone's memories, really – finding a changeling this close to Ponyville should have prompted a massive panic. At the least a patrol to make sure that another invasion wasn't going to go down. She wished that someone other than Scootaloo and her friends had found it, or that they’d gone to Applejack or Rarity instead of to her. Here she was, with a changeling on her couch. She should have left it to die.

But she couldn't.

It was tiny. Scrawny, really, was a better term for it, and ‘very clearly starving to death’ was better still. Or as clearly starving to death as a creature with an external skeleton could be. At least, Dash assumed it had an exoskeleton, based mostly on what Twilight had told her about changeling biology. It went over her head that Twilight knew about as much about changelings as anyone did and was very clearly bullshitting, but looking at one now, up close and still, she wasn't entirely sure whether Twilight was right about that. She prodded the unconscious creature's flesh. It wasn't rigid or hard, the way bugs were. It was soft and smooth, but firm and taught. Like leather. But alive, and warm. Much warmer and more alive than it had been when she found it.

“That's good, right? You’re not dead?” Dash decided that yes, ultimately it was a good thing that it hadn't died. “I mean, like, there's gotta be a reason you were alone and unconscious in the Everfree Forest, and it's probably not that you were planning to invade Ponyville. Right?”

The changeling responded by groaning weakly. It was the first noise that it had made since Dash had brought it into her home, and Dash decided that it was a good sign. Its breathing was less shallow, its slender chest rising and falling more noticeably. Her slender chest? Dash wasn't entirely sure. It was hard to tell if it was a boyish girl or a feminine boy, or just scrawnier than it would usually be because it was starving. But now that Dash was actually looking, she could see its chest ever so slightly swelled, and its hips ever so slightly flared. There were curves there, at least as pronounced as Rainbow Dash's own, if dulled by the lack of flesh on her bones (if she even had bones, but Dash had already finished with that line of thought.)

“I'll be right back. I'm gonna get you some food and water or something for when you wake up. If you wake up.” She winced slightly. Thinking it had been one thing, but her heart sank as she actually raised the possibility that her unusual guest might die out loud.

“Mnnn. No, don't.” That was unexpected. Dash sighed with relief as the changeling slowly cracked open one of her eyes. It was weird, totally unlike a pony's eye. The whole thing was almost solidly blue-green, with iridescent rainbows of colour highlighting where it caught the light. “Stay.”

“'kay.” Dash shrugged, sitting down on the arm of her couch beside the changeling's head.

“Thank you.” The changeling sighed with relief. “Just keep thinking about me. That's good enough.”

“Right, you guys eat emotions. Forgot about that.” Dash shuffled awkwardly. “You're, uh, not gonna, like, leave me an emotionless zombie or something?”

“No, that – mng,” her reply was interrupted by a groan. “That only happens when you're too aggressive with your feeding. Just absorbing ambient emotions like this is fine.” Her eyes slowly fluttered open, shimmering in the warm beams of sunlight that penetrated the cloud walls of Rainbow Dash's home. “Hi.”

“Hi.”

“Thanks for saving me.”

“Well,” Dash blushed, “I mean, I probably shouldn't have, but you're pretty clearly harmless and...” And she'd have felt like a complete monster if she'd left her to die. But she didn't say that because saying it would mean admitting that it was true, and she wasn't quite ready to stop being the hard, tough badass, just in case she turned out to be wrong about how harmless the changeling was. “My name's R-”

“Rainbow Dash, I know.” She coughed as Rainbow Dash raised an eyebrow. “It's, um, a changeling thing. We can sort of... tell what a pony's name is and some basic stuff about them when we, uh, feed. So we can better… You know.”

“Right,” Dash said. “That makes sense. You gonna be impersonating me, then?”

“No, I just figured it'd make things a bit easier if we skipped introductions.”

“We haven't really skipped introductions though. I mean, you know my name, but what's yours?”

“I don't have one.”

Dash frowned. “What do you mean, you don't have one? Everyone's got a name.”

“Well, not Changelings.” The changeling slowly pushed herself upright, swivelling her body around so that she was mostly sitting upright instead of lying back on Dash's couch. “We – fuck, I'm stiff – we don't really need names because we can identify each other just by reading our emotional signature.”

“I can't.” Dash hopped off of the arm of her couch. “I can't just keep calling you 'the changeling,' can I?” She made little quote mark motions with her fingers to punctuate her statement. “I mean, I could, but it's kinda clunky and also maybe a bit racist?”

“Fine.” She stretched in the couch before flopping back. “Butt.”

“But what?”

“Butt. As in ass. Call me that.” The changeling, who was apparently named Butt, frowned slightly, sheepishly avoiding looking Dash in the eye. “It's the closest thing I've ever had to a name.”

Dash raised an eyebrow. “There's a story behind that.”

“Yes.”

“You're gonna tell me.”

“Nope.”

Dash sat beside Butt. “Wasn't a question.” Dash dominated her half of the couch, spreading her legs wide and sprawling her body across as much of it as she could without completely driving Butt off. As it was, Butt moved herself as far to the side as she could.

“It's a touchy subject.”

“Well, if we're going to be friends, then you're gonna have to open up to me.”

Butt blushed, a pale, dark green, barely noticeable against her jet-black flesh. “Friends?”

“'s either that or you're a threat to my home at this point.”

“Right. Okay.” Butt took a deep breath, slender shoulders rising and chest puffing out. “How do I begin this?” She fidgeted nervously. “Okay, so. Stuff like what happened at the royal wedding? Changelings don't normally do that. And by normally, I mean like ever. At all. Waaaaaaay too unsubtle. Usually we build our hives underneath big Pony settlements and live off of ambient emotions, only directly harvesting love occasionally.” She paused, waiting for a nod from Rainbow Dash to prompt her to continue. “Feeding directly usually involves one of two things. Either you impersonate a specific pony and fuck one of their loved ones, or you design yourself a barhopping form and go have a one-night-stand.”

Dash coughed.

“What? Sex is pretty much the best way to get strong emotions out of a pony. Plus it's fun.”

“Just get to the point, okay?” It was Dash's turn to blush and avert her eyes. “And no, I'm not going to fuck you so you can get back to full health, okay? I wanna put that on the table.”

“I wasn't going to ask you to.” She shrugged. “Sex is the best way to get strong emotions out of a Pony, but it's basically the worst way to harvest them. I mean, have you ever tried to eat while having sex? Or even just think about anything other than the sex?” Dash's blush deepened, and a cat-like grin slowly spread across Butt's face. “Oh my god, you're a virgin?”

“Fuck you.”

“You are!” Butt squirmed giddily. “Oh, man, that's gonna be fun!”

“No it isn’t!”

“Hey, if being friends with ponies means sharing embarrassing personal stories, being friends with changelings means casual sex.” She leaned over close to Dash, an arm slowly snaking its way to drape around her neck and over her opposite shoulder. “Lots of casual sex~”

“Yeah, well, it can wait until later, Cassanova.” Dash gingerly lifted Butt's arm off of her and gently shoved her away.

Butt smirked. She was glad to have claimed the dominant position in the conversation. “So yeah, sex is inefficient. That's the important thing to take away from this. Fun, but not actually good for harvesting emotions.” She paused, smirk slowly fading from her face. “Which, uh, is where the nickname comes in. See, I came up with this... I dunno how to put it in a way you'll understand. Hunting strategy, I guess? The idea is that instead of pretending to be someone else, you sort of... Ugh, how do I put this elegantly?”

“Just say it, dude.”

“I know, I'm just trying to not slip into jargon. I know a lot about changeling magic and I'm pretty sure you don't, and I want to make sure you understand just how big of a deal this is.” Dash raised an eyebrow skeptically. “I invented a spell, basically. One that will completely revolutionize changeling society and redefine our relationship with pony society forever!”

“Pretty big talk. How's it work?”

Butt blushed again, sinking her way back into the couch. “Well, that's. Uh. That's where the nickname comes in.”

“Oh.”

“No! No, it's nothing like that! Anal has all the same problems as normal sex.” Dash coughed awkwardly. “It's, like, the spell lets you sort of... merge. With a Pony. Become a part of them. And then you can sort of redistribute your mass around them. Make them bigger. Stronger. Sexier. And then you just sit back and harvest all the love their new and improved form gets.” Dash didn't respond. “It's a symbiotic relationship instead of a parasitic one, basically. The changeling gets easy meals for as long as they stay part of the pony, and the pony gets to be bigger and sexier and even gets some limited access to changeling magic.”

Dash was blushing, Butt noticed. “So, uh, that's it? Don't see where the nickname came from.”

“Well. You see. In order to merge with the pony, first you've got to. Uh. To become part of them. A part of them.”

“Oh.”

“Yeah. You've got to put all your mass into one place before you can start distributing it and...” Butt blushed, angry tears slowly welling up in her eyes. “Here I've invented this completely revolutionary new spell! It changes everything about how we live and feed, but all anyone bothers to see is that I'm that weird drone who wants to turn herself into some pony's ass. Fuckers.”

“Well, uh, does it have to be the ass? Couldn't you start off in any body part? Like, I dunno, a hand or something?”

“No. It's gotta be the butt. That's how it works.”

“Really? I mean, you made it sound like-”

“Technically, it could be other body parts, but the way the spell works, the body part I initially inhabit is always going to be... bigger.”

“Okay. What about tits, then? Or I guess if it's a guy, his... you know.”

Butt shook her head. “Not options. The only parts that are options are parts that aren't... really attractive if they're oversized.”

“Wow okay.” Dash frowned. “Seems weirdly specific. You're sure you don't just want to be somepony's ass?”

“Don't you fucking start with that shit!” Butt leaped from the couch, looming angrily over Dash as best as she could at barely over four feet tall. “It's because you've gotta be fucking, okay? I've gotta stick a bit into the pony I'm becoming part of before I can become part of them, so my options are kinda fuckin' limited!” She angrily prodded Dash square in the chest. “It's either head, cunt, or ass, and two of those look really unpleasant when they've got the mass of an entire other person added to them, okay?”

“Okay, okay, sheesh.” Dash brushed Butt's finger away. “It has to be the butt, I get it.”

“Yeah. It has to be the butt. I wish it didn't, but I can't find a way to get it to work. Any spell that would let me penetrate other body parts interferes with the actual spell that matters.” She collapsed back onto the couch sullenly. “That's how I ended up in the Everfree, by the way. I wanted to actually test it out on a real pony to prove everyone wrong, but...” She blushed, the angry tears returning. “It turns out that it's hard to fuck someone's ass without them noticing. I managed to escape, but it turns out that the weird butt drone going missing isn't a big enough fucking priority.” She spat her words out bitterly. “And I'm not going back. Fuck them. I'd rather die.”

“Well, then stay here.”

Silence reigned for a good solid minute before Butt responded, her voice quiet and strained – almost a whisper. “Excuse me?”

“Stay here,” Dash said again, firmly. “In Ponyville, I mean. I'm pretty sure that once you tell your whole story to everyone, maybe leaving out some of the more, er, lewd details,” Dash paused to cough and blush, “everyone'll be cool with you living here.”

“You're... you're sure?”

“Pft, yeah, don't worry about it. Ponyville's seen weirder.” Dash blushed again. “And anyway, uh.”

“Anyway?”

“Anyway.” Dash coughed nervously. “You said that your spell lets ponies be bigger and sexier, right? How, uh, how much?”

A smirk slowly spread across Butt's face as it dawned on her. “You know, you don't really have any place being insecure considering I'm smaller than you.”

“You haven't been in Ponyville long enough.” It was Dash's turn to be bitter. “Everyone's at least a few inches taller'n me. And even AJ's got bigger tits than me. I mean, I can see having bigger hips, considering how much time she spends on her legs, but she's buff. Buff folks aren't supposed to also have big tits.”

“Well, that's what I'm here for,” Butt purred. “You want bigger tits? You wanna be taller? I've got you. Want a bigger ass? Shit, it's literally where I got my name.”

“Okay.”

“And it's not just that, too. I can make you stronger. Faster. Smarter. I can make you more sensitive. Imagine sex times ten.”

“Virgin, Butt. Remember?”

“Well, you won't have to imagine it. And I can do other things with my mass. Want a cock? Want two cocks?”

“... I'm dubious about one.”

“You won't be once you've tried it out.”

“I wouldn't know the first thing to do with one.”

“But I would.” Butt grinned. “I can take control of your body. You'd feel everything, of course, but you'd be fucking like a pro. And if you're not satisfied with that-”

“Butt you've already fucking sold me can we please just get on with it.” Dash threw herself off of the couch into a standing position. “So, what, you just need to put your hand up my butt or something?” She winced. “Fine, whatever, get on with it.”

“Well, I mean, I could put my hand up your ass.” Butt slowly pushed herself up, stalking her way around Rainbow Dash like a predator eyeing up its prey. “But there's more fun ways to do it. Now, take off your pants and get on your knees.”

Dash swallowed heavily. She knew what was coming at this point. And she wanted it. It was a strange feeling, wanting to be fucked by a complete stranger. But here she was, dropping her shorts to the floor, followed by her panties and then herself. She knelt before Butt like a pilgrim prostrating herself before an idol. She panted heavily, taking in Butt's sleek, shiny form. It was like she was made of latex, sleek and smooth and perfectly unblemished.

“Uh, where's your sex bits?”

“Changeling, babe.” Butt continued to circle the kneeling pony slowly and predatorily. “We don't have sex bits unless we're gonna use 'em. And when we are gonna use 'em, we can have any sex bits we want~” She stopped in front of Dash, grinning wickedly. Her teeth were sharp and perfectly white, glistening in the warm light of the sun as she licked her lips.

Her tongue, Dash noticed, was very long.

“For now, though, let's start simple. I mean, you're a virgin, I don't think your ass could take anything bigger than average. We can go big later. Once we're one person~” She grabbed one of her budding breasts with one hand, rubbing at where the nipple would have been if she'd had one with a clawed thumb. “Ooooh, fuck, that feels good.” She groaned, her other hand snaking its way down her body to rub at her smooth, featureless crotch. “You like this. You really like this. Watching me masturbate. The knowledge of what I'm gonna do to you. The knowledge of what you're gonna be, what we're gonna be. It's turning you on like nothing you've ever experienced before. God, the room's so fucking saturated with your lust it's almost overwhelming~” Butt panted, the pace of her rubbing and groping picking up as her body began to shake. “Tastes so good. Wild and primal, just barely kept in check by – mnggggg – by a thin dam of social norms. That's just one little push away from breaking.” Butt convulsed, her hips bucking involuntarily as soft, feminine folds that hadn't been there moments before parted to take her fingers inside. “God, I haven't eaten this much in months. Feels so fuckin' good.” She moaned, convulsing again and doubling over. “Mnnnnn, you've seen what a malnourished changeling looks like, babe. Now get a load of one who is very well fed~”

Butt lurched forward as her whole body surged outward in every direction. Her hips flared outward dangerously, soft and feminine and wide. Her tits were suddenly each easily as big as Dash's head, capped with a glistening puckered nipple. Her whole form was like that – where once she was boyish and skeletal, now she was soft and vibrant and alive, practically glowing with vitality. She was taller, too. Not as tall as Dash, but more than a foot of difference had dwindled to barely two inches.

And, jutting forth from her crotch was a proud shaft of glistening black flesh, drooling a translucent fluid from its flared head. It was big. Bigger than any cock Dash had seen – which, granted, really just amounted to a handful of stallions, all relatives, and all when she was very young. And none erect of course. Bathing with her father or her brothers back on the very edges of her memories of her childhood. She had little to compare it to, no real frame of reference. But it was definitely big enough that she found herself balking slightly at taking it up her asshole.

“So. What do you think? No, no, don't bother answering. I know. I can feel the jump in your arousal.”

Dash blushed, heat blossoming in her chest as she stared at the mighty shaft before her. “You're, uh, you're not gonna get bigger because I'm hornier, are you?”

“Doesn't quite work like that. To get any bigger than this, I'd have to use magic.”

“Yeah, but you just sort of... exploded there.”

Butt blushed sheepishly. “Yeah, uh, that happens when you don't eat for days and then have a meal this good. But it'd take a lot more emotion than that to make my natural size bigger. Like, imagine the biggest stadium in the world, sold out, with everyone in it twice as horny as you are right now. And all of it'd have to be directed at me, too.”

“Okay.” Dash wasn't really feeling big sentences at the moment. “You're, um. Pretty big.”

“I figured ten inches was a good starting point. If you want it smaller, I can-”

“No! No, it's good. If you think it'll fit, it's good.”

“Okay, good. Let's get started.” Butt gestured to the couch. “I'm thinking doggy style.”

“Right...” Dash was a virgin, but she'd seen porn before. She moved to the couch, kneeling and bending over. She spread her knees, and gave her ass a tentative wiggle.

Butt knelt, positioning herself behind Dash, with her cock level with the pucker of her partner's asshole. “You're sure about this, then?” she asked as she grabbed Dash's cheeks and spread them.

“Just get it over with now, okay? Before I have a chance to change my mind.”

Butt nodded silently, and pressed herself firmly against Dash's ass, rubbing her shaft between her cheeks as best she could. “Geeze, you weren't kidding. Don't really got enough ass here to hotdog.”

“Shut up and fuck my ass!”

“Right!” Butt pulled her hips back, carefully aiming her shaft with one of her hands while the other kept her cheeks spread. “Ready? Yes? Good. Here's hoping this works.”

“Wait, what's that supposed to meeeeaaaaaaaaaaa!” Dash's train of thought was interrupted in a single decisive thrust. It wasn't a pleasant feeling. Her body knew that stuff wasn't supposed to go up there. It felt weird and wrong, and it instinctively convulsed around the intruder in an attempt to get it out the only way it knew how.

“Ffffffuck, you're tight~”

Dash grunted in response. It felt unpleasant, but at the same time it felt good. The cognitive dissonance between the enjoyment and the discomfort was mind-numbing. She squirmed as Butt pushed her body firmly into Dash, eagerly forcing more and more cockflesh into her willing vessel. Even buried up to the hilt, she continued to push.

It felt good. Really weird, but really good. It was like nothing Dash had ever experienced before – she'd masturbated, sure, and she owned a few dildos, but her fingers and toys were nothing compared to the real thing. And she'd never tried anal before – something she was coming to regret. She wasn't entirely sure how much of it was the anal sex and how much was Butt's spell, but her whole body was burning with arousal like she'd never felt before. There was a heat, a need, centred on the point where Butt met her butt, spreading outwards through her entire being like molten metal. She bucked and squirmed and pushed her hips against Butt's as she came from that need alone. “Gnnnnnnnnnnggggggggg~” There was a spark, a spike of arousal an order of magnitude greater than any before as she climaxed, her legs giving out under her. She slipped backwards, from the couch onto the floor, sprawled and panting as she basked in the afterglow. “Holy shit,” she mumbled to herself as she slowly pushed herself up. It took more effort than usual, she noted, and she felt... odd. Unbalanced. “So, it's done?”

“Yep! I'm your butt, now!”

That explained a lot. Butt's voice echoed in her head. That was good. Dash was worried that she'd be literally talking out of her ass.

“Oh, I can do that if you want.”

“Please don't.”

“Fair enough.” Butt shrugged. Dash wasn't sure how she knew, as she couldn't see Butt anymore, but she knew. She could feel it in her-

Well, in her butt.

“So.”

“Why don't you go look in a mirror, and we can see what we look like.”

“Right.” That was something she was going to have to get used to – she was a they now. Two people in one body. She awkwardly waddled her way out of her living room and to her bedroom, where she kept a full body mirror just in case she needed to admire herself.

It was decidedly not what Dash had expected.

She wasn't sure what she had expected. But it wasn't this.

“It doesn't fit in the mirror.”

“Well, yeah, you've got all of my mass plus your ass, which is gonna be permanently more just by virtue of having had me in it. The important thing is that it worked! I was almost worried for a second.”

“Okay I have several questions.”

“Shoot.”

Dash wasn't entirely sure where to begin. “So what exactly did you mean by that 'I was almost worried for a second' there,” seemed like as good a place as any – if only because it seemed the most urgent.

“Well, I haven't actually ever done this for real before.”

“what”

“I figured you could have guessed.”

Dash groaned. “No, but- Okay fine. Whatever. The important thing is it worked.”

“And your butt didn't explode. Also I'm not dead, that's good too. And your butt didn't absorb your entire body, becoming a singularity of ass that consumes everyone and everything around it, ultimately bringing about the end of the world. That's a bonus. And you-”

“Okay I think that's enough of that.” Dash frowned.

“You might glow in the dark now, but we'll have to test that lat-”

“Okay I think that's enough of that.”

“Fair enough.”

“Next question. What's this about my butt being bigger?”

“Well, think of it like this. Your butt is a pair of extra small panties, and me being in them is like a really fat guy putting them on and stretching the waistband. He takes it off, the waistband's still stretched. Only unlike my metaphor, your butt's not gonna get all floppy and empty when I come out of it. Just, you know. Fuller.”

“Okay,” Dash responded tentatively. “And this doesn't mean that everytime you leave my body and come back, my butt's gonna get bigger the next time you leave, right?”

“Well, if the same fat guy puts the panties on-”

“Can you please come up with a different metaphor?”

“No. If the same fat guy puts the panties on again, it's not gonna stretch the waistband more, is it?”

“Oh my god.”

“We're gonna be spending the foreseeable future together, babe, better get used to it.”

Dash groaned, and took herself in. Her ass was comical. She could just barely tell that it was wider across than she was tall. “Third question is what the fuck.”

“Don't worry, this is just temporary!” Dash remained dubious. She would have put her hands on her hips, but she wasn't sure that she could reach. “I just need a moment to get used to things and then I can just sort of... Okay.”

“Okay?”

“Okay. Lemme start redistributing mass.”

Rainbow Dash had expected it to feel better than it did. It didn't feel sexy, it just felt... different, was the only word she could come up with. Not unpleasant. It reminded her of that initial impression of anal. A strange cognitive dissonance. She was used to her body being a certain size and having certain proportions, and suddenly it didn't. “I can make it feel good, but since this is our first time doing this I think we should concentrate on making sure you look good.”

“Right, that's probably important.”

“Okay, so I'm thinking that we don't wanna make you too big too quickly. If only because your clothes won't fit. How's seven feet sound?”

Dash reeled at the thought of being seven feet tall. That would put her at about eye-level with Big Mac. “Yeah. Yeah, sounds good,” she mumbled.

“Okay! That's good, actually. We could go as much as ten feet but that'd leave you pretty much with the figure you had before only ten feet tall. Maybe a bit curvier. This way I have some extra mass to work with. For the fun bits~”

Dash swallowed heavily. “Yay.” She looked up. The roof of her bedroom was an awful lot closer than usual. She breathed in and out deeply and rhythmically.

“Okay, next up is your tits. I'm thinking maybe head sized? Actually, head and a half. Go big or go home, and it's not like you'll ever need a bra while I'm in you.”

Dash stared in the mirror as, slowly but surely, the hem of her formerly loose fitting tank top lifted up and up and up. There was a straining sound and then a loud pop as her sports bra completely failed to stand up to the titans on her chest. Not that she needed one – her tank top had been stretched and deformed to the point that it looked almost like a bikini. “I'm gonna have to get new clothing.”

“Worth it.”

Dash grinned, hefting her new breasts and delighting in the sensation of her hands sinking into her generous underboob. “Oh, fuck yes.”

“Ass is still a little bit silly looking, buuuut I can fix that with some wider hips, which leaves me with just about enough mass left to do this.”

“Gnnnnn!” Dash collapsed forward, once again returning to a prostrate position as her body was overwhelmed by a spike of pleasure.

It was bigger than the one that Butt had grown. Much bigger. Much, much, much bigger – big enough that it had gently smacked her in the muzzle, smearing the milky white fluid that it was leaking copiously on her face. It was thick, too, thicker than her forearm. She would have significant difficulty wrapping both her hands around it, let alone one. It was a dark, dusky blue, glistening with moisture and oozing with overwhelmingly masculine musk – god, Dash could cum just from the smell.

“Still dubious about having a cock?”

“Fuck no.” Dash grinned eagerly. She couldn't see them, but she could feel huge, hefty balls, full of seed. Her seed. Aching for release. She reached down and gave them a gentle squeeze, sending an electric jolt of lust up her spine. Amplified by the knowledge that she could barely fit them in her hands.

“Butt? I think this is going to be the beginning of a beautiful friendship.”

Author's Note

This story takes place sometime between season 2 and 3 - the canterlot invasion is still fairly fresh in everypony's mind, and Twilight is not an alicorn.

The Butt Knight

“Butt? I think this is going to be the beginning of a beautiful friendship.”

Dash felt like she could have just stayed there, revelling in her new body forever. She gave her balls a squeeze – Celestia, they were so huge. Even with her dick being big enough to poke at her face insistently, they still felt fucking massive. She couldn't actually see how big they were – her enormous fucking rack was in the way – but she could feel them, filling her hands and then some, spilling out of her grip in a way that no part of her body ever had before. And, Celestia as her witness, that fact alone more than justified her decision to become Butt's host.

“Ooooh, do that again,” Butt cooed sensually. “Feels so goooooood~”

“What, squeeze my balls?” It made sense, Dash supposed, that Butt could feel everything she could. It was Butt's body being added to her own, after all, that had made all this possible.

“No, no. I mean, that feels good too, but just- gnnnn.” Dash felt... something. She couldn't really describe it. It was completely and utterly unlike any sensation she'd ever felt before. A feeling of fullness and satisfaction, like she'd just finished a massive meal, coupled with a building pressure. “That'd be me,” Butt interjected. “I guess that means you can feel what I feel, too then. Ooooooh fuck this feels way better than I thought it would.”

Butt certainly wasn't wrong about it feeling good, whatever it was. The pressure kept mounting and mounting, compounding itself and filling her whole body with that feeling. Like she was building herself to orgasm just by existing, only times ten. It felt hot and rich and sweet and slightly spicy, though Dash had no idea why those words came to mind.

“That's what lust tastes like. 's always been something of a favourite of mine. I assume you can tell why?”

That made sense. The entire point of Butt's spell was, after all, to form a symbiotic relationship. Dash got to be big and sexy, Butt got to feed off all the various sundry emotions directed at Dash's new, big and sexy body. “But there's no one around besides me, though. Where's the lust coming from?”

“I – gnnnng – I think it's coming from you.” Dash had a difficult time focusing on what Butt had to say. It was, she knew, very important, considering that she was going to have to live with this for as long as she chose to have Butt remain a part of her – and like fuck was she giving this up any time soon. But it was so hard to keep herself from just exploring everything her new body had to offer. “See, changelings can't feed off of changelings. We can't even taste each others' emotions beyond the most basic, surface level emotional signatures we use to identify each other. And obviously, that also means that changelings can't feed off of themselves, right? And I assumed that was gonna extend to you. Like, that I'd be able to feed off of other ponies' emotions, but not yours, because I'm a part of you so it'd be like feeding off of my own emotions. But – oooohhhhhh fuuuuuuck~”

Butt's lecture was interrupted by a thick gout of precum erupting from their cock, splattering directly in Dash's – in their face. Their body quivered with barely controlled need as the lust spiked. Their whole body was full to bursting with the taste of fresh cinnamon buns, with a hint of something Butt couldn't quite put her finger on. It danced on the edges of sensation, accenting and enhancing the flavour of Dash's lust with something different, like nothing Dash had ever tasted before. “That's- that's... I don't have a fucking clue what that is, but it's good,” Butt groaned, as their cock twitched and spurted with more pre. And, with every convulsion, the flavour intensified and built upon itself in a cascading feedback loop of need.

“Mmmmaybe it's you?” Dash grunted through clenched teeth. Their whole body shook with the effort of holding herself back from masturbating. Figuring out what was going on was more important. “I mean, if I can feel you eating my emotions, maybe you can feel me eating yours?”

“That's im-” Butt stopped. Ponies couldn't eat emotions, of course. Under normal circumstances, it would be ridiculous to even entertain the possibility. But, of course, these were far from anything that even resembled normal circumstances. “I don't know, maybe? Merging letting you feel me tasting emotions makes sense, but you being able to taste other people's emotions as well? I guess it's not out of the question but, I mean, it's kinda hard for me to figure out one way or another because- Gnhaaaaaannnn~”

“Shit,” Dash muttered in between heavy panting. It was getting harder and harder to think straight with every passing second. Her cock twitched and pulsed, a raging river of precum gushing forth in volumes that would make even the most copious orgasm from a normal stallion seem pathetic. And, aside from squeezing her balls earlier, she hadn't laid a single finger on herself. “I dunno, maybe we should split up again so you can figure out what went wrong with the spell?”

“Fuck that shit!” Butt shouted, in conjunction with another convulsion and another copious blasting of precum. “This feels way too good to just stop!”

“Well, okay, plan B then.” Dash reached up, grabbing what was once a tank top but had since been stretched beyond recognition by her new form, and effortlessly tore it off.

“Plan B? What's plan Beeeeeeeeeeeeeeee?!”

Butt's train of thought was completely halted as Dash grabbed their tits and squeezed them tightly around their cock. “Oh fuuuuuuck~” she groaned, pausing her motions. “Saw this in a porno once. Gnnn, girl wasn't nearly this stacked, though.”

“Bet it wasn't her own cock she was doing it to, either. Why'd you stop?”

“Caught off guard by how good it felt,” Dash gasped. Their hands fell to their sides, their cock's weight causing it to drop forward out of their cleavage. “And my- sorry, our bits are kinda too big for just one pair of hands.”

“Hm. Actually, hold on, I have an idea.” Dash felt a tingling sensation in her – their armpits. “Sorry, this might get a bit weird.” Dash didn't have the chance to ask what Butt meant by that before she found out, rather abruptly as an extra pair of arms burst forth from beneath their original pair. “There, much better!”

The new pair of arms glistened, slick with moisture. Dash idly noticed that they were a changeling's arms, not a pony's – Dark, shiny, and black, like Butt's had been. They looked rigid, but felt soft and smooth enough against the skin of her cock as she grabbed it at its base with one hand. The other grasped it higher up along its length, pulling it close to her body as her upper pair again pressed against her tits, pushing them against it and enveloping most of its length in soft, warm flesh.

It felt good. Her shaft was slick and hot and rigid, pulsing against her tits in time with her heartbeat. The warm, tight tunnel her cleavage had formed around it rubbed up and down, her quivering and throbbing causing enough motion to provide the needed friction to push her higher and higher and higher. Closer and closer to that glorious release. Just holding her cock in place with her tits was a million times better than the most intense thing she'd felt before, blowing the previous record holder of 'existing while being big' out of the water. And she hadn't even started titfucking herself yet.

“Oh shit,” Butt muttered. “Oh shit, oh shit, ohhhh shiiiit~” Dash felt that insistent, overwhelming pressure spike. The spicy sweet flavour of lust compounded on itself exponentially, accented by the now unmistakable earthy, musky flavour of what could only be Butt's emotions. Her cock was now leaking a constant geyser of precum, splattering directly on her face. She idly, instinctively licked up some of the slick fluid from her lips and groaned lewdly. “Moooooooore,” Butt moaned, accompanied by a noise. Low, wet, and primal, like a cross between a rumbling stomach, a growling animal, and a goddamn earthquake. “Oh shit, Dash, we need to stop.”

Dash was barely capable of registering Butt's words over the vast sensory overload she was experiencing. “Wha?” she muttered, licking her lips again, staring at her cock with a level of determined, needy focus that she'd never felt before.

“No, seriously, Dash, we actually need to stop.”

“Okay,” Dash forced out. Butt sounded serious enough to poke through the haze of still-building arousal.

“Hold on, I'm going to have to leave your body for a bit. Just gimme a sec...”

Dash felt what she could only describe as Butt's merging spell, only in reverse. Which made sense, she supposed, since that was what it was. Her cock was gone, her breasts were smaller, and she was once again just barely over five feet tall. The only real sign that anything had happened was the not insignificant extra padding down below, pushing her hips slightly higher than they would have been prior to being Butted. She found herself sprawled on the ground, facing the ceiling, with Butt awkwardly lying face down across her belly. “What was that about?” she muttered, reaching up to rub her temples. She found herself with a pounding headache.

“That was me almost going into a feeding frenzy,” Butt muttered, her voice muffled by the ground. “Which would have been bad, by the way. Best case scenario, we would have ended up stuck in an endless feedback loop of feeding on our own emotions. Worst case, you turn out to not actually get anything out of me feeding and you end up hollowed out, or just starving to death. Or you end up hollowed out and starving to death.”

“Could you get off of me?”

“No. I'm staying here forever.” Dash frowned, and feebly prodded at Butt's side, hands sinking into the soft curves she had apparently managed to retain. “Hey I just saved your life sort of probably maybe the least you could do is let me die in peace.”

“Butt you lardass get off of me you weigh a fucking ton.”

“Excuse you, you don't just call a lady fat. That's what we in the business call rude.”

Dash weakly shoved at Butt's hips again, hands sinking into the soft flesh of her thighs. “Tell that to these.” She giggled slightly. “Butt's got a fat butt. Appropriate.”

“It's not fat, it's full figured,” Butt replied with an indignant huff. “At least I have a figure without outside help.”

“I'm an athlete! Rigorous diet and exercise, man, I can't help it.”

“And I can't help it if you're fattening.”

Dash rolled her eyes. “Fine. Whatever. Could you at least roll off of me? It's kinda hard to breathe with you just sorta on top.”

“In a minute. I'm trying to take stock of what went wrong.” Butt ignored Dash's frustrated groan. “So I went into a feeding frenzy. The big question is why did I go into a feeding frenzy, and by extension how can we stop me from going into another every time I join a host.”

“I certainly can't imagine given how very well fed you clearly are.”

“And whose fault is that? The other big thing we learned was how apparently being merged gives the host some abilities I, uh, wasn't exactly expecting. Like apparently being able to sense my emotions even though that should be impossible. Changelings are like an empathic black hole. Could you please stop poking my butt? I'm trying to think here.”

“Not until you get offa me.”

“Hmph, if you're gonna be pushy that just makes me less inclined to go along with you. So what I think happened is that once I merged with you I became a part of you, which means my emotions suddenly count as your emotions. Pony emotions, not Changeling. Which, since I can feed off of you, means that I can basically feed off myself.” She paused to contemplate, and Dash continued to poke her butt. “I, uh. I'm not sure why that sent me into a feeding frenzy though. Maybe being merged uses up more energy than I thought? But I'd have noticed if I was runnin' hot... Okay, okay, fine, if you insist, I'll get off. I think I've mostly recovered anyway.”

Butt slowly rolled off of Rainbow Dash, sprawling her body across the floor of Dash's bedroom. “Theory. Being the host doesn't just give you the ability to sense and taste emotions, it basically just sorta takes the host's pony digestive system and the changeling's empathic digestive system and makes a kinda weird hybrid of the two. Which is naturally bigger because now it's two people's digestive system instead of just one's. I figure that it does need more energy to run, being bigger and all, I just didn't notice in time because I'm not used to the weird hybrid digestive system. In layman's terms, because we're bigger we need more food.”

“Okay, I guess that makes sense,” Dash replied slowly. She'd sort of managed to follow Butt's logic. “So that means that, like, we'd be able to eat normal food and also emotions?”

“Yeah, that's the gist of it. We're just gonna have to eat for two when we're one.”

“Makes sense. How do we fix it?”

“Easy. We've got two options. First, Option B.”

“Wait, hold on, why option b? Why not option a?”

“Because you're definitely not gonna go for it so I'm gonna talk about it first instead of the one that we're prolly gonna use. 's more elegant that way.”

“'kay,” Dash responded, rolling her eyes.

“Option B; you and I merge with one or two extra ponies around and then we have an orgy. Harvest some extra love from them in addition to our own love. Feeding frenzy still happens, but we mitigate it with volume.”

“Ech. Okay, I can see why you said I'm definitely not gonna go for it.”

“Yeah, I figured you weren't quite up for operation 'have an orgy every time we merge' just yet. Which brings us to Option A.”

“Which is..?”

“Make sure both of our tanks are full to fucking bursting before we merge. That means I need to gorge on emotions, you need to pig out on cake or something I don't know what ponies eat.”

“They eat your ass,” Dash responded grumpily. She was too fucking exhausted after the experience that had been merging with Butt to have the patience to deal with the changeling's somewhat baffling cultural ignorance.

“Oh so you wanna start with me then~”

“Not what I meant. Too tired to fuck.”

“I figured. Don't worry, you're not alone.” Butt attempted to push herself upright, and mostly succeeded. She was slumped over herself, but she was sitting. “So we take like an hour to recuperate and then what? Try again?”

“Let's save that for now, actually.” Dash sat up more easily than Butt did, though pulling herself upright took some effort. “I figure that before we make this arrangement even a regular thing, much less permanent, I'm gonna need clothing that fits for just like day to day living.” She extended a hand to Butt. “Which means that we're gonna hafta go shopping. Which, uh, probably means telling everypony else about you.”

Butt took Dash's hand and pulled herself upright. “I mean we were gonna have to do that eventually. I should probably make myself presentable first. I don't think this is the first impression of myself I wanna cultivate around Ponyville, you know?” she said, briefly gesturing over her body. Her genitals had put themselves away, but she was still armed with head-sized tits, birthing hips and a weapons-grade ass.

“Eh, you'll be fine, probably.”

“I think I'll make myself a bit more family friendly before we go out. Just, you know, to be safe. Save this for the bedroom~”

Dash rolled her eyes again. “If I'm gonna be going around Ponyville seven feet tall with a cock bigger'n Scootaloo, you can go around Ponyville with big tits.” She stretched, briefly, before yawning. “Anyway, speaking of the bedroom, I'm gonna hit the hay.”

“Sounds like a plan. I could use a nap myself.” Butt turned to leave. I can sleep on the couch for now, I figu-”

“Pft, fuck that.” Dash grabbed Butt and dragged her to the king-sized bed in the centre of the room, roughly throwing her onto it.

“Woah!” Butt bounced slightly from the impact on the soft cloud of Dash's mattress. “I thought you said you weren't up for sex?”

“If we're going to be one person on a permanent basis anytime soon, we'd better get used to sleeping in the same bed. And besides-” Dash shuffled her way up onto the bed without actually standing on it, straddling Butt on her knees. She loomed in a way that was a jarring contrast to her earlier uncertainty, before lowering herself to her hands and knees, face inches from her changeling's. “I think I've just found my second wind.”

“Oh, well, uh, I guess I'm up to it if you are, but-”

Whatever it was Butt had to say, Dash abruptly cut it off by leaning in and kissing her. She moved her hands, one at a time, off the bed and onto Butt's fat tits. She eagerly pawed and groped and squeezed at them, eliciting soft moans, muted slightly by the kiss. Butt's hips rocked gently, grinding against Dash's muscular thighs of their own accord as Dash pinched at the glistening black nipples that had come into existence.

Dash grinned confidently as she broke the kiss, allowing Butt some fresh air. “You taste good,” she managed to mutter.

“You've mentioned,” Dash replied before flopping over onto her side. “By the way I totally lied about getting my second wind.”

“That's okay I lied about being up to it if you were.” Butt melted into the bed, limbs splayed in every direction while Dash slowly scooted out of her way. “You really do taste good though. I could definitely get used to it.”

“Well, I mean, that's prolly for the best considering you're gonna be tasting me a lot now. I'm not sure but I think we're technically dating now?”

“Changelings don't really do dating.”

“Ponies do, though. Duh.”

Butt shrugged weakly. “I don't think this can be compared to normal pony relationships.”

“And it's anything like normal changeling relationships?” Dash asked, which Butt responded to by shrugging again. “I figure we can work out the boundaries and rules later on. Set some basic ground rules now to avoid the most obvious bits of stupid relationship drama, but we can do the actual hard work after I have a fucking nap.”

“Cool.”

“Open relationship?”

“Probably a good plan. I mean, I'm definitely going to want more sources of food than just you or else we run the risk of hollowing you out and no one wants that.”

“Yeah. And let's face it, there isn't much point in the whole merging arrangement if we never actually use our combined body for anything other than masturbating.”

“A-fucking-men to that.”

“That was easier than I thought,” Dash said, practically yawning the words.

“I should also really probably deal with these,” Butt muttered, hefting her tits.

“You don't really have to worry about it. Trust me, you're not even close to the most well endowed po-person in Ponyville.”

“Yeah, but I should at least put a fucking shirt on or something. I'm not gonna be spending all my time merged with you, or at least not yet.”

“Fine, fine, we're going clothes shopping tomorrow anyway, we can buy you a shirt or two, maybe some pants. You can prolly go commando.”

“Yeah changelings don't usually do underwear.” Butt shrugged weakly again. “Really, we don't usually do clothing unless we're in disguise. A changeling in pony society out of disguise is kind of a new thing in general.”

“So then we've pretty much got our schedule for tomorrow. Start off with a big-ass breakfast 'cause we're gonna need to merge to get measured for clothes. And at some point in between we're gonna hafta introduce you to Twilight.”

“Twilight?”

“I'm really not in the mood to explain Ponyville politics. Short answer is that she's a friend who's got a direct line to Princess Celestia – you at least know who she is, right?”

“She's the big kahuna, right?”

“Yeah pretty much. We can stop at the library, talk to Twilight about you living here from now on and, uh, the whole thing where you tried to merge with somepony by putting your dick in their butt without permission. Then she can get in contact with the Princess while we stop at Carousel Boutique and Rarity can get to work on some outfits.”

There was a moment of silence before Butt spoke up. “Ah. This Rarity pony's a friend of yours, then?”

“Sorta. We're closer than we used to be but mostly we just know each other through Twilight.”

“Ah. She wouldn't happen to have white fur and a purple mane and tail? Three diamonds as a cutie mark and a really big butt?”

“Yeah, actually, how did you- oh. Oh.”

“Yeah.”

“Well,” Dash muttered with mild irritation. “This is gonna be awkward.”

Author's Note

holy shit this thing's baaaaaack! i swear i'm gonna try and update my stuff more frequently guys.