“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.