Morning sunlight streamed through the bedroom window, illuminating a purple unicorn who clearly had not had a very restful night. “Aaugh!” Twilight Sparkle’s eyes snapped open, scanning around her in a panic. She jerked her body back and forth, trying to wriggle free of her bonds—but it was her familiar comforter and bedsheets, not a mass of black vines.

And then she slid off her bed, striking the wood floor with a Thump!

“Whuh?!” Spike jerked awake, sitting up in his bed-basket. “What happened? Twilight, are you okay?”

“I… I…” Twilight’s eyes darted around, taking in the sights of her bedroom in the Golden Oak Library. “I think I’m okay?” With a flash of her horn, she teleported herself free from her entangling bedsheets. A quick glance in the mirror confirmed Twilight was back to normal: no oversized rump, no inflated belly, no blue spots on her horn, and not even any bedhead. In her coat and mane, every hair was somehow perfectly in place.

“So what were you shouting about?” Spike asked. “You sounded really scared!”

“It was just a bad dream.” Twilight glanced at the mirror again and sighed. “Just a dream…”

She teleported all her bed linens into the laundry room. “Might as well get an early start on the day,” she said, setting off for the bathroom.

As she washed up, her mind was elsewhere. She didn’t even notice how the water just flowed off her, how her face and mane had become water-repellent…

—————

Today was grocery day, so Twilight left for the market right after breakfast, leaving the library under Spike’s supervision. And it was at the market that she realized something was wrong.

Twilight had just bought a dozen apples and was chatting with Applejack. Then, without any warning, two hooves touched her haunches and squeezed. After a quick yelp, Twilight spun away from Applejack, ready to give her molester a verbal lashing he’d never forget. But when she turned, she instead saw…

“Rarity?”

“Oh!” Rarity said, her deep blush standing out like a beacon against her white coat. “I’m so sorry, Twilight! I don’t know what came over me!”

“Rarity, you grabbed my rump? Why?”

“Desire moved my hooves before my brain could tell them otherwise. It shan’t happen again, darling, that’s a promise.”

“No… that’s…” It took all of Twilight’s self-control to refrain from smacking her own face with her hoof. “Why did you want to touch my butt in the first place?”

Rarity gasped. “Who wouldn’t want to touch it?”

“What.”

“Really, Twilight, have you looked at yourself in a mirror lately? Why, your coat is so smooth and glossy—” Rarity placed a hoof on Twilight’s withers and ran it down her shoulder, producing a quiet but unmistakable squeak, “—and so soft. Darling, you must tell me sometime how you did this.”

“I didn’t do anything!”

“Very well, then. Keep your secrets. Anyway, coat aside, your rump is simply to die for, Twilight! It’s big and round and bouncy…”

“What?” Twilight snapped her head back to survey her backside, and it was indeed just as Rarity described. Her haunches were at least a foot wider than her middle; her rump was large enough that the simple motion of looking back was enough to set her cheeks wobbling.

And Applejack, still behind her cart, was staring at that rump, slack-jawed. As soon as Twilight noticed her, Applejack turned away and counted the bits from her last few sales again, blushing furiously.

Rarity continued, “Normally, on a svelte figure like yours, a butt that large would look grossly out of proportion. But you pull it off, somehow, Twilight! Your mixture of ‘small-town librarian’ and ‘mare of the night’ flouts every convention I can think of, but it just works!”

Twilight turned back to her. “‘Mare of the night’?”

“Oh, I’m sorry. I mean ‘mare of negotiable affection’.”

“What’s the hay is going on?! My rump isn’t normally this big!”

“Oh, don’t sell yourself short, darling. That delectable derrière of yours has been turning heads since you first came to Ponyville. Isn’t that right, Applejack?”

“Hm?” Applejack looked up from the newspaper she had been studying. “Oh, yeah. Gotta agree with Rarity for once. Twilight, first time I saw yer butt, I thought to myself, ‘Golly, if only I was a stallion, then I’d plow that like the east field.’”

Twilight’s jaw dropped and her left eye twitched.

Rarity coughed. “Well, you put it a little more crudely than I would, but I can’t disagree with the sentiment. I thought I was straight as an arrow, but I can’t count the times this month alone that your pulchritudinous posterior has tempted me!”

“No, no,” Twilight said. “This isn’t right! Something’s—”

A rainbow streak blasted down from the sky, landing right next to Twilight. “Hey, girls,” Rainbow Dash said. “How’s it hanging?”

Then she gave Twilight’s rump a hearty slap, eliciting a loud Squeak! from the rump and an “Eep!” from the pony.

“Butt’s looking as good as ever, Twi!”

“I need to get out of here,” Twilight said. She started trotting away from Applejack’s cart, and her backside—still jiggling from Rainbow’s slap—bounced even harder with every step.

And suddenly there was a pink blur blocking her path. “Hey, Twilight!” Pinkie said. “Have you seen my purple balloons?”

“Um, no?” Twilight said. “Why do you need—”

“I’m stashing balloons all over Ponyville, in case of balloon emergencies, but I misplaced my purple ones!” Pinkie circled around Twilight as she rambled. “They’re not in Sugarcube Corner, or in Miss Cheerilee’s classroom, or in Town Hall, or underneath the bridge, or in Fluttershy’s house, or—” Directly behind Twilight now, Pinkie let out a loud gasp. “There they are!”

Then she grabbed Twilight’s haunches and squeezed, more tightly even than Rarity had. Those purple cheeks wobbled and squeaked in her grasp.

“Pinkie!”

“Oh,” Pinkie said. “These aren’t balloons. It’s just your butt.” She squeezed again. “Even better! Boingy, boingy, boingy…” Again and again she squished the rump, making it bounce in time with her inane chorus. “...boingy, boingy, boingy, boingy!”

“Yee-haw! Go, Pinkie!” Applejack shouted.

“Yeah!” Rainbow Dash added, salivating at the sight. “Squeeze her good and hard!”

Rarity said nothing, but stared at the scene intently, and levitated a paper fan to cool herself off.

“Get off!” Twilight telekinetically shoved Pinkie away, then spun to face her four friends—keeping her large, still-jiggling backside out-of-sight. Except that was no longer possible: every other pony in the market, buyers and sellers alike, had been attracted by the commotion and now formed a circle around Twilight and her friends. They stomped and cheered and whistled, and some of them called out:

“Shake it, baby!”

“Over here! Let me see!”

“Play ‘Free Bird’!”

“No, no…” Twilight said, as she spun frantically in place. “This is crazy, this is all crazy! I look weird, and everypony’s acting weird! There must be some kind of magic affecting—”

“Mmmm…” A familiar voice said, right behind Twilight.

The pressure on her haunches returned, and this time a weight settled atop her backside as well. Fluttershy was hugging her rump, and resting her head on it like a pillow. “I hope you don’t mind, Twilight,” she said. “But it just looked so comfortable. I couldn’t resist.” Twilight’s posterior squeaked and wobbled as Fluttershy nuzzled it, a serene smile on her face all the while.

Twilight’s eye twitched again, and she teleported to the edge of Ponyville, then ran.

—————

Twilight’s gallop slowed to a canter. Nopony was chasing her—in fact, she hadn’t seen anypony in the last… How long had she been running again? Twilight had no answer, and that brought her to an abrupt stop.

For the first time since her mad dash started, she took stock of her surroundings—then gulped. There was no sky overhead, just a leafy canopy. There was no horizon, just trees as far as the eye could see. In her blind panic, Twilight had somehow run right into the Everfree Forest.

“Okay, this definitely has something to do with my dream last night,” she said. “I dream about turning into rubber and getting my butt inflated, then suddenly I look like this…” Twilight glanced over herself. Her rump almost looked bigger than it had been back in Ponyville, but with how much it jiggled she couldn’t quite tell.

“And I dream about getting lost in the Everfree, and now here I am. It can’t be a coincidence. Wait, actually…” She looked down, at the clear, wide path beneath her hooves. She looked up, at the horn on her forehead—a bit shinier than usual, but still perfectly healthy. “This time I’m not lost.”

Twilight didn’t have any spells that would show her the way back to Ponyville, per se. But she did have the next best thing: a spell that could lead her to the nearest house. She cast it and smiled at the glowing beacon it conjured, pointing straight ahead. Then her smile fell. “Wait a second…” Twilight cast her compass spell, and furrowed her brow at what it showed.

The Everfree was south of Ponyville—yet Twilight’s locator spell said the nearest house was further south.

Sighing, Twilight set off in the indicated direction anyway. She tried to keep as quiet as possible, lest she attract the attention of some predator, but silence was impossible at this point. Her body was so rubbery that she squeaked with every step.

A few minutes later, Twilight found the house. From a distance, it resembled any other tree in the forest, albeit with strangely colorful, eye-catching fruit. But drawing nearer revealed a door and windows in that trunk, and the “fruits” were actually glass jars suspended from the branches. It was a house carved into a living tree, not so different from the library that Twilight called home.

It was also the only sign of civilization that Twilight could see. Approaching the door, she briefly wondered what sort of pony would make their home in the middle of the Everfree. Then she knocked, the door opened, and her question was answered: Not a pony at all. A zebra.

“How strange,” Zecora said. “I come to you ponies, and you all run away. But now, you’ve come to me. But why, I must say?”

Twilight’s ears flattened, and she lowered her head. “I’m sorry about that. My friends in Ponyville are afraid because they’ve never seen a zebra before. I was trying to show them that there’s no reason to be afraid of you, and things got out of hoof, and… I’m sorry.” She raised her head again, and one forehoof. “I’m Twilight Sparkle, and I’d like to be your friend.”

“‘Friends’ may be premature,” Zecora said, then smiled. “But we shall see. Zecora is what you may call me.”

She met Twilight’s hoof with her own, the gold bands on her foreleg jangling at the motion. The purple hoof squeaked at her touch, so Zecora brought it closer to her face. “Stranger still. You’ve a rubbery sheen—like no pony in my life I’ve ever seen.”

“Yeah…” Twilight pulled out of Zecora’s grasp—her foreleg appeared to stretch a bit before popping free. “I, uh, just started looking like this today. No idea what could have caused it.”

“Many strange effects come from plants of the Everfree. And one might hold the cure, perhaps. We will see.” Zecora pushed her front door all the way open and stepped back from the threshold. “Will you step in? I was about to brew tea. Then, all about this problem, you can tell me.”

—————

Twilight told Zecora everything.

She had meant to withhold some of the more personal—and embarrassing—details, but something loosened her tongue. Perhaps it was the calming effect of this tea, some flavor she’d never tasted in all her years of tea parties with Princess Celestia, yet still vaguely familiar. Perhaps it was Zecora herself, who smiled warmly through the entire story and said nothing to judge—yet Twilight couldn’t help but imagine seeing a will of granite behind those cyan eyes, one who would accept nothing less than the whole, unvarnished truth.

So Twilight told Zecora about her strange, nested dreams. Sipping her tea (so black it nearly had a purple sheen), she told how Zecora herself appeared in those dreams, each time using Twilight and transforming her against her will. As Zecora poured her another cup, Twilight told of the inexplicable changes that had come over her this morning (noting silently that she sat a little higher than usual, and that her plus-sized rump squished over the edge of her seat). Between sips of her second cup, she told of her friends’ uncharacteristic interest in her posterior.

Twilight finished that cup just as she finished her story. “...so I cast a beacon spell to show me where the nearest house was. And that led me here.” She returned her cup and saucer to the table, idly noting that Zecora’s teacup was still full.

“Hmmm…” Zecora said. “This is quite the vexing mystery…”

“But you have some idea what could have caused this, right?”

“To unlock it, I think your dreams are key.”

“You think they were prophetic dreams? I mean, I’ve never had one before, but this would be a swell time to get one, I guess.”

Zecora, saying nothing, lifted her teacup.

Twilight scratched her chin; the resulting squeak undermined her gravitas. “Or do you think this is some kind of magic from the dream realm, blowing into the waking world? Our knowledge of dream magic here in Equestria is such a void, waiting to be filled…”

Zecora inhaled deeply, then set the cup back down.

“I just don’t understand how my dreams could possibly affect me and my friends like this. Everything I can think of is just such a stretch.”

Zecora replied, “There’s a saying you ponies love to impart: ‘A dream is a wish, made by the heart.’”

Twilight blinked—and even that motion produced a quiet squeak. “Are you… implying… that I want to be like this?”

“If you say so. I cannot know.”

“I’m not saying so! You’re the one bringing it up!”

“Then why speak of ‘a stretch’, ‘a void waiting to be filled’, and ‘a swell time’? Those words and phrases were all yours, not mine.”

“No, no, you’re blowing this out of proportion.” A second after she said it, Twilight clamped her forehooves over her mouth, her eyes wide.

“Here’s what I see,” Zecora said. She leaned forward, both forehooves on the table, and Twilight could almost imagine she was a few inches taller. “As an evil enchantress, I appeared in your dream. A plausible portent of the future, that seemed. And how did you answer this vision you were shown? Why, you rushed off to see me, completely alone. With no plan and no magic, you went on your way. As if you wanted the enchantress to make you her prey.”

“No, I didn’t want it!” Twilight said, her voice higher and squeakier than she intended. “I just… wasn’t thinking!”

“Then you dreamed of plant molestation, and a rubbery transformation. And that your rump grew like a balloon—but when you awoke, did you change your tune? Two parts of your dream had somehow come true, and you ran off blindly, as if asking the third to happen to you.”

“No, no, that’s impossible!” Twilight, looking up at Zecora, remembered what it was like to be a filly, standing in Princess Celestia’s shadow. Even as the zebra kept smiling at her, she couldn’t help but feel smaller and smaller. “I would never—”

“And when I fixed you my polymorph potion, you drank two whole cups. I made no disguise for the flavor, yet you drank it right up.”

“No! I—” Twilight squeaked, then her eyes went wide.

The tea. Zecora hadn’t drunk anything from her cup. And Twilight did recognize the flavor: it was the same potion Zecora had dosed her with in the dream last night.

Twilight glanced frantically around, looking for the door, and her heart sank. Zecora really did tower over her—because Twilight herself had shrunk. She ran for the edge of her stool—the seat was as wide as the library’s main room, relative to her—and gazed down at the two-story drop to the floor.

Backing away from the edge, something on Twilight’s right foreleg caught her eye. There was a dark, slightly raised line running along the inside of her leg, and a matching one outlining her underhoof. Her left foreleg had a mirror image of those same lines. In fact, there were more lines running along her hind legs and the rest of her body—even along her tail, whose hairs had somehow fused together into one solid piece. Twilight put forehooves to her face and mane, and felt more lines there. And then she knew what they were: seams.

Before, she was a rubber pony. Now, she was some inflatable doll in the shape of a pony—and a miniscule pony, at that.

A black hoof—larger than Twilight—slammed onto the seat just in front of her, the impact shaking the whole stool. “Eeep!” She started to scurry away, but Zecora’s other forehoof came down, blocking her path. Twilight looked up, at the giant, gray-striped face overhead.

“Well?!” Twilight squeaked. “What do you want with me?!”

“No, no, don’t ask what I want,” Zecora said, in a voice that rumbled like thunder in Twilight’s ears. “What you want is what matters to me.” In one swift motion, she grabbed Twilight in the crook of her right pastern. “And the effects of the potion, you must be quite eager to see…”

Zecora held Twilight up with both forehooves: grasping the unicorn’s forelegs in her left hoof, and her hind legs in her right. At this scale, Twilight could see the telekinetic field from the zebra underhooves, holding her tight. And then Zecora inched her hooves apart, pulling the miniature unicorn between them. Twilight’s legs went straight—then began to stretch, and her torso with them. Like a rubber band, she extended to twice her normal length. Blushing, Twilight grunted and tried to pull herself free, yanking on her forelegs, then her hind legs, but all that did was make her wobble as she stretched farther and farther. Four times her normal length she was pulled, then five times, six times…

“Now that’s something you don’t often see.” Zecora chuckled. “So much better like this, don’t you agree?”

Without warning, she clapped her hooves together. In the blink of an eye, Twilight snapped back to her normal proportions—and then her rump smacked into the back of her head, while her legs bent around each other, their joints squishing into her torso, which compressed like an accordion. After less than a second, she was squashed into a purple disc, thinner than a bit coin and slightly wider than the hooves holding her.

Zecora removed her left hoof, exposing Twilight’s flattened face—blushing bright red against the rest of that purple surface. Her eyes spun in their sockets, and her tongue stuck out the side of her squashed muzzle. But her liberty was short-lived, as Zecora once more grabbed both sides of that purple disc. Once more she pulled, stretching the unicorn as far as before and then even farther. Twilight shook her head, then glanced between her forehooves and hind hooves, gulping as she was pulled wider than the stool below. Longer and longer she grew, a purple rubber band vibrating uncontrollably in Zecora’s grasp.

“Aargh! Let me go!” Twilight squeaked. She was, relative to her shrunken size, stretched far enough to wrap around her own house at least twice. And her blushing face was no longer the only part of her growing warmer. “Let me go!”

And Zecora let her go. Twilight’s stretched extremities whipped back; her posterior once more struck the back of her head, before she snapped back to her normal proportions and flopped onto the stool.

A shadow fell over Twilight. She looked up just in time to see the giant, striped butt descending from above. Zecora sat on the stool, and Twilight suddenly found herself squeezed between the wood below and the huge, soft rump cheek above.

“Oh dear—I promised tea, but never gave you a taste,” Zecora said. “I’m such an awful host. I must fix this posthaste.”

She stood back up, revealing a purple shape on her posterior. Twilight—squashed flat, spread-eagle, and blushing even brighter than before—was stuck tightly on the zebra’s backside. With every step Zecora took, Twilight stretched slightly, clinging to the contours of that rump as it flexed and relaxed. Her eyes darted back and forth frantically as she bounced along with that cheek.

Zecora grabbed the tea kettle and dumped all the undrunk potion into the boiling cauldron at the room’s center. A black mushroom cloud rose from it and quickly dissipated, but the contents of the cauldron began to bubble and churn. Zecora, meanwhile, filled the kettle with water and hung it next to the cauldron, over the fire.

Then she returned to the stool by the table. Its wooden surface rushed up to meet Twilight, and she had just enough time to gulp before she smashed into it again. Zecora’s rump plopped onto the chair and jiggled at the impact; Twilight felt every vibration.

Sighing, Zecora settled in to wait for the kettle to boil. But she couldn’t sit still, and kept shifting in her seat—each time, pressing Twilight’s face harder into the wood grain of the stool. That rump’s soft hair brushed over every square inch of Twilight’s flattened body; Zecora’s every twitch shook Twilight to her two-dimensional core, which was growing warmer by the second.

“Mmmmmm!” Twilight tried to protest, her voice muffled. “Mmm, mmm!”

In response, Zecora began bouncing in her seat.

“Mmmmmmm!”

After what felt to Twilight like hours upon hours of dark, squishy softness, the kettle finally boiled, and Zecora rose to add the tea leaves. Once more, Twilight stuck to her backside all the while—until Zecora reached back, grabbed Twilight’s tail, and peeled her off like a sticker.

Holding the flattened unicorn in one hoof, Zecora said, “That’s enough time to steep and cool, I think. So now it’s time for you to drink!”

With the kettle resting at the table’s edge, she popped Twilight’s muzzle over the spout. Relative to the shrunken unicorn, the tea kettle was larger than the Ponyville water tower. Zecora placed one hoof on the handle.

“Hrrmmhhmm!” Twilight protested, futilely fluttering her flattened limbs, her body flapping feebly in the air.

Zecora tipped the kettle forward. Hot tea poured out the spout, straight down Twilight’s throat. The liquid filled Twilight, restoring her to three dimensions once again; within seconds, she was back to her former proportions. But the tea kept pouring. Her rump, already larger than usual, was the first part affected: her backside quickly expanded twice as wide as her torso. When her rump cheeks resembled a pair of beach balls, her belly began inflating as well, growing until she looked pregnant with twins, then triplets.

“Mrrblblglblglblgl…” Twilight cried against the flood of tea, filling her larger and larger. She raised her forehooves to the spout and tried to push herself off, but that just stretched her face and neck—her lips remained sealed around that opening, pouring more and more liquid into her. Her hind legs spun in the air, sloshing her still-filling rump and belly with every futile kick.

As Twilight inflated with four times her volume in tea, her whole torso began filling, not just her belly. Her back rounded out, and her sides bulged like love handles around her already-bloated haunches. Wider and more bulbous, her backside swelled with the endless flow of tea, while her thickening cheeks slapped against each other from the frantic motion of her hind legs.

But as she expanded farther, her kicking slowed, and eventually stopped. Then—Bloosh!—her left hind leg stuck straight out, swelling full of tea. Bloosh! Her right leg did the same, thickening to twice its normal width. And then—Bloosh!—so did her tail. “Hhmmglglblglblgl…” Twilight protested, beating her forehooves against the spout until—Bloosh! Bloosh!—those legs also filled with tea and stuck straight out. She blinked, her eyes darting from her swollen, immobile limbs, to the massive kettle still pouring into her. She was completely helpless to do anything but gulp down more and more tea—ten times her volume already, and no end in sight.

“I’m glad to see how much you like my tea.” Zecora said. She tipped the kettle forward further, ensuring a constant flow of the liquid. “Drink as much as you’d like—don’t worry about me.”

Twilight sloshed back and forth on the end of the spout as she inflated even farther. She was almost spherical now, a purple balloon with legs and a tail—and even those were beginning to sink into her body. Her rubbery skin squeaked as it stretched farther and farther to contain the flood of tea; it squeaked even louder at the places where her bloating torso swallowed the base of her legs. Gulping down fifteen times her old volume, Twilight blushed harder than before. The heat on her face was matched by a growing fire between her hind legs—one that had nothing to do with the temperature of this drink. She screwed her eyes shut and tried to scream, but it just came out as more gurgling.

The kettle tipped a little further, and Twilight’s cheeks bulged from the increased flow of tea. They brushed against the bloated curves that had been her shoulder, as her neck sunk slowly into the balloon of her body. Larger she inflated, to eighteen, nineteen, twenty times her volume, growing from a rubber doll to a rubber ball. Twilight would have perspired, if her transformed body had sweat glands. Her face and loins both burned. Her skin grew warmer, especially along the seams, with every inch it expanded to contain the endless volume of tea pouring into her, filling her relentlessly. As she inflated to twenty-five times her volume, a small part of Twilight mind wondered if her seams would hold—if the stinging she felt was a harbinger of their tearing apart. Then that part promptly joined the rest of her mind in screaming incoherently, while her body ballooned larger and larger.

At long last, the kettle tipped all the way, and the tea stopped flowing. Twilight gulped down those last mouthfuls, adding a final few inches to her diameter, before Zecora popped her off the spout. Filled with over thirty times her volume in tea, Twilight was a purple beach ball in Zecora’s grasp, with her head and hooves barely poking out from her bloated sides.

“Mwah…” Twilight said.

Zecora squeezed her, prompting a squeaky “Eeep!” from Twilight as she jiggled and shook between those gray hooves.

“I must admit, this is a good start,” Zecora said. “But something is missing—some vital part.” She spun Twilight around to examine her rump. And that was the problem: Twilight didn’t really have a rump anymore. It had merged with her body’s overall sphere shape, giving her a uniformly curved backside where there should have been thick, squeezable cheeks. Zecora took a deep breath.

“What?” Twilight squeaked. “What are you do—Eeeee!”

Zecora placed her lips just below Twilight’s tail and blew. Warm breath rushed through Twilight’s backdoor and inflated her rump. Two subtle bumps rose from that purple backside: rump cheeks slowly but steadily gaining shape as they filled with air. Larger, rounder they grew as Zecora kept blowing.

Twilight tried to protest, but all that came out was “Aaaaaaaaaaaaaa…” She shook her puffy, sunken limbs as far as they could move—barely an inch in any direction—in a desperate bid to wiggle out of the zebra’s grasp. But Zecora just squeezed her again, setting her ballooned body and inflating rump a-wobbling. And as Twilight wobbled, Zecora’s lower lip brushed against her lower lips. “Hhhhhnnnnnnnnnnn…” Twilight said, her blush deepening.

More and more air blew into Twilight’s rump, inflating those cheeks from mounds to proper hills. Her tail bobbed in circles atop them, inching higher and higher as they grew beneath it. With another squeak, her hind hooves sank completely into those ballooned haunches. From Zecora’s perspective, that rump was like a pair of tennis balls embedded in a beach ball—but from Twilight’s perspective, her backside was already large enough to fill her bedroom back in Ponyville. And that warm breath just kept expanding it, larger and larger. Zecora released Twilight’s bloated torso and held her by the rump instead, to feel it widen within her grasp.

“Aaahhh, mmmmnnnn…” Twilight bit her lip, trying to keep hold of her mental clarity under this sensual barrage. Her rump grew more and more sensitive the further it inflated—Zecora’s grasp on her expanding backside was a touch of the divine, and the air blowing into her was the very breath of Heaven. “Unnnnhhhh…” Zecora gave another squeeze, and that proved too much for Twilight. With a helpless moan, Twilight shook her legs in earnest, wobbling her whole body and brushing her marehood against Zecora’s lip over and over.

That purple rump ballooned bigger than a pair of honeydew melons, and Zecora just kept blowing, filling it ever larger. In spite of Twilight’s initial shrunken state, her cutie marks had stretched back to their normal size, and now expanded even farther as her haunches just kept growing. The larger Twilight inflated, the more she wobbled—bucking faster and faster against Zecora’s lip, stimulating herself into a frenzy. Twilight panted and moaned, her eyes rolling back in her head, as her rump expanded beyond all rational thought.

“Hhhhnnngg!” At last, Twilight could take no more. She stopped bucking and simply trembled all over; every muscle in her body tensed, while her brain completely let go. Her tongue lolled out of her mouth as she gave a long moan of incoherent pleasure.

Zecora had finally stopped inflating her. Instead, she clutched the ballooned unicorn to her chest—all the better to feel the throes of Twilight’s orgasm. And Twilight was more rump than pony at this point: each of her cheeks was individually larger than her beach ball-sized torso by a few inches. They, along with the rest of her bloated mass, shook and jiggled against Zecora’s chest, before finally going still.

“Was your pleasure well-earned?” Zecora asked.

“Uhh… I… uuhhhh…”

“Great! Now it’s my turn.”

“Wait, what?”

Zecora shifted her grip, holding Twilight’s bloated torso a bit behind the spot where it swallowed her neck. Once again, she squeezed—but this time, she slid her hooves past each other, as if rolling a lump of dough or clay into a thin cylinder. And that’s exactly what she did: as Zecora’s hooves worked back and forth, Twilight’s front half grew thinner and longer in between.

“Wha—? Ugh— Hey!” Twilight squeaked, rotating back and forth between Zecora’s hooves. And as she became skinnier in front, all that missing mass flowed into her backside, filling her rump to even more enormous sizes.

“And there we go,” Zecora said, setting the transformed unicorn on her bed. “The ideal shape, you know.”

Twilight’s haunches and rump, swollen large enough to make a comfortable seat, rested on the mattress, while the front of her body wobbled in the air—long, thin, and distinctly phallic. Eyes wide, Twilight bobbed back and forth. She was completely immobile and helpless: her hind legs engulfed by her huge haunches, and her forelegs flattened against the shaft her body had become.

So when Zecora climbed onto the bed, turned around, and stepped backwards, Twilight could do nothing but stare at the sight. Zecora’s tail lifted and exposed her marehood, gleaming with arousal—and slowly bearing down on Twilight. As that dark flower drew closer and closer, her eyes widened, and a sound escaped her throat—a whimper or a whinny, even she couldn’t say.

Then Twilight screwed her eyes shut as her snout brushed the zebra’s folds—but Zecora just rubbed Twilight against the outside. Up and down, up and down Zecora wiggled, smearing her arousal all over that purple shaft.

Twilight sighed with relief—and then Zecora sat on her, shoving Twilight’s head right into her puckered backdoor. The passage was velvet-soft but almost unbearably tight. Further and further, Zecora pushed herself onto her unicorn-turned-sex-toy, sliding the helpless Twilight deeper, inch by inch. Lewd squelches filled the room, the sounds of Zecora’s feminine juices lubricating the way for the rubbery unicorn.

Twilight panted, as every buck of Zecora’s hips plunged her deeper. Squeezing within these hot, humid depths was like a deep-tissue massage inside a sauna. The feeling was exhilarating, and the smell of sex was intoxicating; Twilight was getting turned on again, in spite of her confusion and fatigue.

All the while, Zecora bounced up and down, whinnying with pleasure. With every bounce, she slid a little lower, shoving a little more of the rubbery purple toy into herself.

Ignored by both of them, the cauldron had kept bubbling and churning all this time. Now, something broke the surface of the liquid—something long, slender, and green. A single tentacle felt its way over the cauldron’s lip, then down to the floor, and slithered towards Zecora. Shortly after, three more tentacles emerged and followed their brother across the room.

Twilight, forced deeper and deeper into Zecora, yelped as something pressed into her enormous, sensitive backside. The first tentacle poked, prodded, and groped at her ponderous, purple rump—and the other three quickly joined it. Twilight’s cries of pleasure echoed through Zecora, prompting the zebra to buck even harder and clamp tighter on the unicorn inside her.

Meanwhile, the two thinner tentacles began exploring, tentatively probing between Twilight’s cheeks. One of them stopped at the entrance to her marehood; the other rested just beneath her tail. Twilight gave another incoherent yell—prompting more pleasured whinnies from Zecora—at their touch. Even those tentacles, the thinner of the quartet, were still much too wide to fit either of Twilight’s orifices, shrunken as she was. So instead they caressed the entrances—lapping up and down, circling around, and teasing her in every way they could. Their gentle touch made her moan with pleasure, relaxing slightly.

And that’s when the tentacles penetrated Twilight, ramming several inches deep with one rough thrust. She screamed as both orifices stretched and stretched—forced wider than she ever thought possible by the tentacles’ girth. Pain blossomed from there, but seconds later gave way to unmeasurable pleasure, as her rubber body reshaped to accommodate the invading tendrils. Both tentacles pushed further, rhythmically thrusting without rest, until Twilight wondered if they could possibly go any deeper. Then the one in her marehood slid out, almost all the way—just to push back in again. And the one in her back door followed suit, a few seconds later. The motion of the two tentacles was offset: one thrust into Twilight while the other jerked back out, then vice versa, over and over and over and over.

Zecora, meanwhile, finally hilted Twilight inside herself, sliding all the way down the purple toy until her muscular rump squished against Twilight’s bloated backside. At that, Zecora’s hind legs wobbled and gave out; she tipped over and landed on her back. And as the tentacles continued plowing Twilight, they slid her in and out of Zecora, stimulating the zebra even further. Back and forth, back and forth, the shrunken unicorn slid, while Zecora moaned and arched her back, kicking with all four hooves at every thrust.

The tentacles widened at their bases—and those bulges moved, speeding along the tendrils’ length, towards Twilight. They both reached that purple backside and forced their way inside. Twilight moaned again as the tentacles stretched her even wider—as their tips flared deep inside her and spewed slime, filling her even more than before. Then the second pair of bulges forced itself into Twilight before the first was completely spurted out, then the third after that, and then the fourth. Twilight’s rump inflated even further as the tentacles pumped payload after payload of slime into her. That already massive posterior, squished between the tendrils behind and Zecora’s rump in front, sloshed and wobbled as it filled with a mare’s entire volume, and then even more.

Buried in Zecora’s rump, Twilight whinnied with pleasure, growing louder by the second. Again and again, the two tentacles pistoned in and out, and widened inside her all the while. They kept ejaculating slime into her, each payload larger than the last, with no end in sight. Twilight’s rear inflated as big as two exercise balls, and then even larger. Her thickening haunches brushed against the wall on one side, and squished over the bed’s edge on the other. Those cheeks sloshed and wobbled, slapping against each other and the wall, shaking the whole bed underneath as they grew and grew.

“Hhhng!” Zecora’s head smacked against her pillow as Twilight plowed into her ass over and over. That massive purple backside squished against Zecora’s rump in the process of swelling even larger; with every pleasured kick Zecora gave, her hind legs squeezed a few inches into the rubbery unicorn. Twilight was wobbling against her, shaking inside her, which just made Zecora pant and moan even louder.

Twilight spread across the floor as she inflated even further, filling with a fathomless quantity of tentacle slime. Each rump cheeks was already bigger than Zecora’s bed, and still growing. Bulge after bulge, each with at least a gallon of liquid, surged along those tentacles and pumped straight into Twilight, relentlessly expanding her.

Deep inside Zecora, Twilight panted harder than ever at the sensation. Her ballooned backside had been sensitive before—and now that, from her shrunken perspective, her cheeks were both individually larger than the entire Golden Oak Library, that sensitivity was almost unbearable. The slightest touch against that huge purple balloon—whether from the floor, or Zecora’s kicking hooves, or the cauldron at the center of the room pushing back when she expanded into it—now felt even better than the thick, meaty tentacles plowing her endlessly.

The more Twilight filled the room, the louder and longer her moans became. As her massive rump pushed the cauldron across the floor—as it bulged around the stool and squished against the table where this madness had begun—her core burned with arousal, hotter even than last time.

“Grrrraaaaaugh…” Zecora tensed all over, arching her back, sticking her hind legs out, and clenching her haunches—squeezing a bit of Twilight’s rubbery body between her legs as she came. That squeeze pushed Twilight over the edge. Her entire body tightened as her mind was once again lost to overwhelming pleasure. All she knew was the soft, humid tightness of Zecora’s inside; the impossible fullness of the thick tentacle flesh penetrating her, still relentlessly thrusting in and out, even as they pumped endless gallons of slime into her; and the strange but incomparable pleasure of her skin stretching beyond all rational limits. So Twilight shook and moaned inside Zecora, the two mares orgasming together.

At last, Zecora sighed and went still. She wiggled her torso and pushed against Twilight’s bloated backside—her hooves sinking nearly a foot into that rubbery posterior that filled half the room and continued expanding—slowly pulling herself off the unicorn-turned-sex-toy.

All the while, Twilight continued shaking and wobbling, and not just from Zecora’s jostling or the tentacles’ thrusting. She was still in the throes of her orgasm. Every time her climax started to diminish, some other sensation—another payload of tentacle slime, another squeeze from Zecora’s hoof, another poke from some piece of furniture she bulged against—would set her off again, even harder than before. Her rubbery rump was more sensitive with every inch it grew, and now it was miles wide from her perspective, and still growing relentlessly. Every touch on those massive purple globes triggered a wave of pleasure, each more intense than the last—each enough to spur Twilight into another orgasm all by itself.

Zecora finally pulled herself free. She sat up on the bed, turned away from Twilight, and lay back, resting against that gigantic backside like a pillow. “Mmmmmmmm…” she said, a smile on her face, as she sank several inches into that rubbery softness. Slowly, casually, Zecora’s forehoof reached down to her own groin and caressed her marehood.

Twilight just squeaked and vibrated even harder under Zecora’s weight, stimulated further still by the pressure. She bulged around the zebra’s back as she expanded; she pushed the cauldron, the table, and chairs so far away that they wedged between her haunches and the walls. A slight pressure pushed down on the highest curves of her rump: Twilight inflated large enough to brush against the ceiling. As more and more gallons pumped into that backside—filling her larger than Ponyville, from her perspective—she pressed hard into the ceiling and began spreading across its surface.

Twilight was completely helpless. Not only was she immobilized by the relentless expansion of her back half and the compression of her front, but her mind was paralyzed by the constant stream of orgasms as well. Even her cries of pleasure just came out as incoherent squeaks. Twilight was barely a pony anymore, and more some kind of furniture—an inflatable cushion for Zecora to recline against while she masturbated. And inflate Twilight did: her massive rump squishing across the ceiling, her haunches covering the walls. Everything her gigantic backside bulged around—the shelves, the decorative masks on the walls, hanging bottles and cooking implements, the front door and windows—pushed back as she filled every corner of the room, sending tidal waves of orgasmic pleasure to utterly drown her brain.

In the one corner that Twilight hadn’t filled with her inflating bulk, Zecora pressed herself deeper into that purple rump as she came down from her climax—only her second of the day. Smiling calmly, she clapped her forehooves twice. And at that signal, the tentacles finished ejaculating into Twilight, pumping in those last few gallons before they pulled out of her entirely and disappeared back into the cauldron. Twilight finally stopped expanding and simply sat in place—still jiggling and climaxing uncontrollably, her mass almost completely occupying the room.

Zecora shifted in place, prompting more pleasured squeaks from her purple cushion, then grabbed a blue bottle, hanging from the wall next to her. The lid had a built-in eyedropper, which she used to squirt a couple ounces of blue potion into the shrunken Twilight’s mouth. The effect was almost immediate: Zecora suddenly found herself sitting atop Twilight’s normal-sized head. Her rump rested on Twilight’s mane, and the horn ticked between her haunches. It was soft and rubbery.

Once more, Twilight had upper body of an ordinary mare—or rather, an inflatable toy the size of an ordinary mare—but she stuck out from a backside still large enough to fill Zecora’s house. This antidote had restored her to normal size, but with absolutely no effect on the mind-boggling volume of slime still inside her rump. But even as that volume remained the same, it felt smaller from Twilight’s perspective: now her rear was merely room-sized, instead of city-sized. Fortunately, this made Twilight much less sensitive back there, bringing her constant stream of orgasms to an end. Unfortunately, the size change left her still sensitive enough back there; as Twilight came down from her climax, she was rudely pushed right back to the precipice, but not over.

“Ooooohhhhh…” Twilight moaned. Her voice was back to normal, but she still squeaked with every movement. She pawed at the bed and tried to squirm, but Zecora held her down, and Twilight made no effort to remove the zebra rump from atop her cranium. “Oooooohhhhhh…”

“This seems a good stopping point to me,” Zecora said, a sly smile on her face. “How about that, Twilight? Don’t you agree?”

“Nuh… no,” Twilight said, in between heavy panting. “Don’t stop now…”

“Oh, really?” Zecora clenched her legs, pressing her haunches to the sides of Twilight’s head. “You wish to go on?”

“Yes… Don’t leave me like…”

“I should keep playing with you—that’s what you want?”

“Yes, yes!”

“I should do things to you, unspeakably naughty? I should have my way with your gorgeous body?” Zecora squeezed harder, slightly squishing Twilight’s rubbery head between her muscular haunches.

“Yes, please!” Twilight cried. “I’ll be your toy! Your plaything! Whatever you want me to be! Just, please—”

Zecora cut her off with a kiss—curling forward to meet Twilight’s lips upside-down. Twilight’s eyes widened, then she relaxed and returned the kiss. “Hmmmm…” Zecora broke it off, just long enough to climb off Twilight and turn around to kiss her properly. Zecora’s forelegs embraced her, hooves running up and down the seams in her rubber mane.

“Whatever I want?” Zecora said in between kisses, “Well, I have a hunch, that what I want most right now… is some lunch…”

She leaned forward again—but instead of pursing her lips, she opened wide. Twilight’s whole muzzle slid easily into Zecora’s mouth. The unicorn’s eyes widened. “Mmrrh?” she wondered.

But Zecora just chuckled. Firmly grabbing the back of Twilight’s head, she pulled. Zecora’s mouth opened wider, and wider, and wider—stretching impossibly as Twilight’s forehead, cheeks, and jaw passed through. Twilight found herself in wet darkness, her entire head inside the zebra’s mouth, and with those lips around her neck. Before she could react, Zecora grabbed Twilight’s forelegs and pulled the unicorn further into her mouth, until her lips came to those purple shoulders.

“Zecora?” Twilight asked. “What are you doing?” She was too aroused to be afraid of this latest development—just confused. Her snout poked into Zecora’s throat, and then her whole head slid into that slick, tight tunnel, as Zecora swallowed her further. Those lips slipped past Twilight’s shoulders, pinning her forelegs to her torso.

“Ooooohhhh…” Twilight moaned, as she was devoured further. “Mmmmmm…” Inside Zecora’s throat felt even tighter—and more like a sauna—than the last time she’d been inside the zebra, just a few minutes ago. In spite of Twilight’s uncertainty, every inch she slid down that velvet-soft passage pushed her closer to yet another orgasm. Her chest made its way into Zecora’s mouth, then her belly, and suddenly Twilight’s face pressed into a wet, soft wall: the back of Zecora’s stomach.

By that point, Zecora’s lips were around Twilight’s flanks, inches from the point where those haunches jutted straight out. Twilight’s room-filling posterior was the only part that remained to be eaten. “Mmmmhhhmmmm,” Zecora said through her mouthful of unicorn. She reached down to pat her distended belly, the gentle pressure of her hoof caressing Twilight through her stomach.

“Mmmmmmmmmm…” Twilight replied.

Then Zecora grabbed as much of Twilight’s haunches as she could fit between her forelegs—a tiny fraction of its gigantic mass—and pulled it into her maw. Inside her stomach, Twilight gave another wordless cry of pleasure as she climaxed once more.

And Zecora grabbed more of Twilight’s backside and gulped that down, then did it again, and again, and again. Her jaw opened impossibly wide, her neck bulged, and her belly expanded until it squished into the mattress below. But it was Zecora’s rump and haunches that grew the most, rapidly expanding twice as wide as usual, then three times, then wider still. Like a pair of weather balloons, her cheeks inflated, jiggling and wobbling with her every movement, and slowly engulfing her hind legs.

“Mmmrrrrrrrrr!” Twilight cried with pleasure, right into Zecora’s stomach lining. Those hooves squeezing her bloated backside—the tightness as her haunches compressed to fit into Zecora’s mouth—it was too much for Twilight’s sex-addled brain to handle. Every time she started to come down from her orgasm, Zecora would grab and swallow another mouthful of her, which would just set her off again. Twilight was trapped in another endless cycle of brain-melting pleasure, helpless to do anything but expand Zecora’s rump from the inside.

Already, that rump was twice as large as the rest of Zecora, and it just kept growing. She scooped more and more of Twilight’s gigantic posterior into her maw, expanding herself further with every mouthful. Her hind legs sank further into her haunches, already up to their fetlocks. Her black stripes stretched along the surface of her haunches, as did her sun-sigil cutie mark, widening inch after inch. That wobbling mass squished into the wall behind—began to spill off the bed, just as Twilight had—and still it inflated larger and larger.

“Hhrrrrrmmmmm…” Zecora moaned. Her words were muffled by all the Twilight in her mouth, but her pleasure was obvious all the same. The vibrations of her voice traveled through her own body, stimulating Twilight even further and then jiggling her stripey rump as it ballooned more and more—each cheek filling to four times Zecora’s normal volume, and even larger.

Meanwhile, gaps appeared between Twilight’s backside and the walls and ceiling. Every few seconds, bits of furniture and cooking utensils clattered to the floor, no longer pinned to the wall by those rubbery purple haunches. Twilight’s rump was deflating: the slime from the tentacles drained from her into Zecora, slightly faster than the zebra could swallow her body. And every inch that Twilight shrank was another inch added to Zecora’s haunches.

The stripes on Zecora’s rump were feet wide now; her cutie marks were bigger than her cauldron. Her hooves disappeared completely into those black-and-gray balloons, leaving infolded divots where they sank beneath the surface. That backside towered over the rest of Zecora, already brushing against the ceiling, and still inflating even larger. More and more of Twilight’s mass she gulped down, adding foot after foot to the diameter of her own gigantic rear. For an instant, both rumps were the same size—then Zecora blazed past that halfway point, her cheeks wobbling and shaking all the while.

Zecora’s ass grew to dozens upon dozens of times the weight of an ordinary zebra. Her cheeks and haunches covered the doors and windows—any passers-by would have seen nothing through those panes but a wall of black and gray—and spread across the floor just as quickly as Twilight’s rump retreated. Zecora filled over two-thirds of the room, and still she grew larger. She bulged over her own furniture and squeezed into corners, taking up more and more space with her relentless expansion.

Meanwhile, as Twilight’s rear shrank further, it slowly regained its former shape. Her puffy hind legs emerged from the divots that had swallowed them. Her deflating haunches grew distinct from her rump cheeks. And those legs became thinner, until Twilight could once again kick them—those hooves jerked in the air, not as an escape attempt, but in response to Twilight’s latest orgasm.

Then, Zecora paused, with Twilight’s now-normal-sized rump in her distended mouth, with those hind legs still poking out and kicking. Instead of swallowing, Zecora reached up with her forehoof, caressing between those haunches. Up and down she brushed on Twilight’s marehood, until a muffled moan and shaking from deep inside signalled that Twilight had appreciated the hoofjob.

Then, with one last gulp, Zecora completely devoured Twilight, those hind hooves disappearing down her throat like candy. “Ahhhhhhhhhh…” she said, reaching back to rub the nearest curve of her gigantic haunch.

“Ohhhhhhhhhhhhhhhh…” Twilight answered, inside Zecora’s belly. She was restored to her normal proportions, but now Zecora’s stomach was squeezing and caressing her all over. Every inch of Twilight’s body felt as good as that last hoofjob, as good as the prodding and groping on her enormously inflated backside. She had barely come down from her last climax, and already she was building up to yet another one.

Meanwhile, Zecora was once more in the room’s only free corner. Every other square inch was filled, from floor to ceiling, with her titanic ass. That striped rump pushed against every surface, squeezed into every crevice, and even bulged a few feet through the open doorway to other rooms. Zecora patted it and watched it jiggle. “Thank you, Twilight, for such a wonderful meal,” she said, then yawned. “But now I must nap, with how drowsy I feel.”

If Twilight could hear those words, inside Zecora’s belly, she was in no condition to respond. Unspeakable pleasure racked her body, from head to hooves to tail, and she orgasmed all the way into unconsciousness.

Author's Note

I can’t take credit for “mare of negotiable affection”, but I don’t remember who I originally heard that one from, either.