The Will of Desire

by Non Uberis

Rating: mature
Tags: Equestria Girls, Sex, Sunset Shimmer, Twilight Sparkle (EqG), Alternate Universe, Anthro, Porn, My Little Pony: Friendship is Magic, Fetish, Horror, Romance
Length: 13154

After being introduced to the study of magic, Twilight Sparkle wants to cut her teeth by casting a spell on Sunset Shimmer. It may test their limits, but they're willing to experiment.

Since coming to Equestria, Twilight Sparkle has been taking great strides in advancing her knowledge of the arcane arts, and Sunset Shimmer is all too eager to assist her (with some lurid incentive as a bonus). After mastering the basics, Twilight Sparkle has decided she would like to move on to something more advanced, only for that desire to become overtaken by a rather out-there inclination. Sunset Shimmer has her doubts, but she's willing to put them aside for her marefriend. She'd do anything for her, after all. And if it means getting bigger tits, what could the harm be?

= = = = =

This story is a continuation of the events of An Equestrian Fling.

Contains the following: anthro, NSFW, casual nudity and frivolous sexuality, hyper (breasts, butt, lips, vulva, cock, balls), possession, corruption, bimbofication, growth, fat/BBW, muscle, multi (breasts), shortstack TF, latex TF, female-to-intersex, strrrreeeeeetching, mild body horror, making out, groping, lots of vaginal play, penetration, extreme insertion, masturbation, and books.

All characters are mature adults.

Cover art by Marauder6272 and Blues64. (DB ID 2827957)

Published 2022-11-01 20:50:01 UTC
Last updated 2022-11-01 20:50:01 UTC

Practical Applications

“You have to start with the internal focus,” Sunset Shimmer instructed, “focus on your horn and summon the magic there. Don’t start just yet though—it will build quickly, if you wait too long you run the risk of a far more explosive discharge than we want. The last thing we want is to blow up another of the Princess’s treehouses.”

“O-okay,” Twilight Sparkle muttered, biting her lip at the prospect of what accidents might transpire.

“Your horn will automatically expel magic in the direction it’s pointing, but you can aim it manually if you concentrate on a target.” Sunset Shimmer leaned around the lavender mare and extended a hand in the direction of their designated training dummy: a coat hanger with a bulky jacket and hat perched upon it. She had insisted on additionally tacking on a hastily doodled portrait of Abacus Cinch. Anger was a strong motivating emotion when casting offensive magic, after all. “But remember, you have to start casting the spell first; you’ll have to be quick on your hooves with expelling the energy.”

Twilight Sparkle didn’t look much more confident, but she still nodded her head.

“Here, let me help you steady yourself.” But Sunset Shimmer made sure to add a teasing lilt before she placed her hands on the other mare’s shoulders and pressed into her back.

That was enough to break through her anxiety, prompting a quiet gasp and then a chortle. “Are you sure you’re not trying to distract me?” She rolled her shoulders and wings, pressing into the bare breasts which were mashed against her.

“I like to think it’s just another form of incentive.” The unicorn leaned in for a quick peck on the cheek. “Now go and light that bitch up.”

After all that trepidation, it went by without much fanfare. Twilight Sparkle faced forward and took a deep breath. She had closed her eyes before when she needed to focus, but this time she kept her eyes centered upon the dummy. Her horn sparked with violet light before welling up from within, an intense glow. The intimate contact of bodies pressed together was forgotten as a low growl welled up in her throat, bursting in a short cry as she released the energy. A bullet of light erupted from her horn. Sunset Shimmer thought she saw, for a split second, the projectile hitting square in the center of the paper sheet before there was a vibrant burst of energy and the dummy toppled over.

Sunset Shimmer whistled while Twilight Sparkle gasped from the exhilaration. “Nice shootin’, princess,” she said, clapping one of her shoulders. “Let’s take a look.” With her own aura of teal magic she lifted the pieces of the dummy for them to inspect. The coat hanger had broken in three places. The coat was singed and the hat had fallen off. The doodle had been incinerated.

(She dimly reflected that it was a good thing the magic bolt had landed, considering they had neglected to consider the bookshelves positioned behind it; explaining to Princess Twilight why a chunk of her library had been obliterated wouldn’t have been fun to look forward to.)

“Oh, wow…” Twilight Sparkle whispered breathlessly.

“So,” Sunset Shimmer then said nonchalantly, “you know what that means next, right?”

They began without waiting for any response—they were both eager and waiting for it. Sunset Shimmer’s hands reached around the other mare, one finding a nipple and the other reaching down to pry open the slit between her legs. Twilight Sparkle promptly crooned like a cow being milked, a passionate exultation furling out from the depths of her being. Her wings struggled, fighting to stretch out, in the process pushing harder against Sunset Shimmer’s bosom. She reached backward clumsily and planted her hands on her partner’s hips, right over the sun markings, partly for support and partly to knead and caress the supple flesh.

The routine had gone on like this in roughly the same way each time Twilight Sparkle succeeded in casting a new spell. They would gasp and grunt and groan until the alicorn reached orgasm, her moist loins tightening around Sunset Shimmer’s fingers.

But this time, the unicorn didn’t notice the magenta glow that manifested until there was something prodding at her crotch. She had just enough opportunity to drunkenly mutter “What?” before the object forced its way inside, and that reduced her voice to a sharp grunt. She recognized the ephemeral texture and the slight tingling that it brought with it immediately: a magical construct, inserted into her vagina. Not that she had much time to ruminate upon that before it then began to pulse, vibrating rapidly, and she cried louder while redoubling the force with which she was fingering her marefriend, really putting the squeeze on her, grasping a fistful of the pliant flesh that comprised her oversized breast. Sunset Shimmer would prove to be too preoccupied with cumming to notice when Twilight Sparkle came, juices spurting and drooling down both their legs. The construct faded out of existence at the exact same time, leaving her nether lips to snap back shut abruptly.

“What…wh-what was that?” she sputtered once the rush of exhilaration was over.

“O-oh, I…I wanted to t-try something,” Twilight Sparkle replied, smiling wryly while panting for breath. Her horn lit up once again, and the air shimmered before a magenta shape manifested from nothing: a sphere which then morphed into a cube and then a pyramid. “Since I had figured out…magical constructs…I wanted to see about…applications.” The construct then changed again, elongating into a cross between a cylinder and an ovoid—a very approximate dildo.

“Heh…well, not bad,” Sunset Shimmer replied, genuinely impressed, “you can still learn how to make proper anatomical details, but it gets the job done well enough.” She then traced a cum-stained finger along the alicorn’s breast and whispered, “I’d say that merits another reward.”

Twilight Sparkle produced a protracted, trembling gasp, a surprisingly good whinny. But she then readjusted her glasses and took Sunset Shimmer’s wrist, pulling her away before insisting, “No, I’ve had enough of these parlor tricks. I want to look at some of the real spells. I want to try my hand at real magic.” Though that didn’t stop her from licking at the other mare’s fingers, lapping up her own juices.

The unicorn smirked, albeit more from pride welling up within than any remaining horniness. She knew it was a bit of a rush for someone who had just become a pony—let alone one who was tapping into the inherent power of an alicorn—to jump so quickly from elementary cantrips to real magic, but she knew that Twilight Sparkle was always going to be a voracious learner no matter what universe she was in. It made her glad to know that her marefriend was adapting so well and so eager to accept the new aspects of the world she found herself in, despite the misgivings she had once held. And, of course, that she was receptive to the sexual promiscuity which pervaded pony life.

When they had had enough of groping and grinding for the time being, the mares separated from each other and approached the table at the center of the library. There wasn’t a lot of free space on the counter, as vast swathes of the room’s contents had been emptied onto it in huge stacks. It might take the average person or pony years to read through them all, but Sunset Shimmer was certain that Twilight Sparkle would devour the lot of them by the end of their stay. Unless the sex proved to be too much of a distraction. Sunset Shimmer herself was scarcely able to stay contained for the duration of one of their lessons; it was always overpowering at first, coming back after being so used to the mundanity of the human world, but having her girlfriend-turned-marefriend with her had prolonged that mire of arousal. The scent of alicorn musk still swirled about them, and it would be some time longer before Twilight Sparkle was either fully satiated or able to control it. Not that she was showing it at the moment as she looked longingly at the books before her—the thirst for knowledge was still powerful enough to quash the carnal hunger of the loins.

“So where should we start?” Twilight Sparkle asked giddily, bouncing on her hooves, a motion which caused her to wobble tremulously up and down her curvaceous physique.

“That’s a pretty broad question, you know,” the tawny unicorn replied, “there are many schools of magic, Twilight, just as there are many forms of study in science.” Her horn lit up and she levitated several books from the pile, letting them circle about, a gallery view of one after another. “Illusion, transmutation, conjuration, abjuration, and dozens of subdivisions within those.” She grinned as she saw a twinkling of wonder and awe behind Twilight Sparkle’s glasses. “How about you think about…something you always wished you could do when you were a human. What’s a superpower you would have liked to have?”

After a few moments of deep thought, Twilight Sparkle replied, “Oh, can I learn how to teleport?”

A part of Sunset Shimmer inwardly grimaced. Teleportation was relatively commonplace among ponies who were attuned to magic, but that didn’t mean it was easy. It took a great deal of focus to accomplish, and a miscalculation could lead to disastrous results. Many unicorns getting started with the spell took for granted how difficult it could be and consequently failed to prepare adequately for it.

But a greater part of Sunset Shimmer was excited because she knew that Twilight Sparkle would be able to pull this off.

She had to forcibly repress still another part that dreaded the idea of the alicorn effortlessly accomplishing yet another task set before her.

“Alright, sure,” she responded, clapping a hand against the small of the other mare’s back. “That should be…hmm…” She brought the books toward herself, squinting at each of the covers for a second before dismissing them one by one, then turning her attention to the table and bringing forth more. “Where is it…?”

“What’re we looking for?” Twilight Sparkle asked, igniting her horn and bringing an additional flow of books in a shimmering magenta current.

“There’s got to be a copy of Starswirl’s Essentials here somewhere,” Sunset Shimmer muttered, almost more to herself as she focused on her search. She was certain she had seen the blue and white cover while unloading the books earlier, and it should have been near the top of the stacks, yet she had maybe a fifth of the assortment up in the air at the moment and still hadn’t found it. She was concentrating hard enough that she was tuning out the sensation of cool air upon her exposed skin and the scent of estrus and the ever-present prickling of arousal.

“Um…Sunset? What’s this?”

The unicorn turned toward Twilight Sparkle’s voice and looked at the book she was holding.

She immediately looked away, dismissing it upon seeing that it wasn’t Starswirl’s Essentials.

Then she paused and returned her gaze, while in the background the cloud of books settled to the ground.

The book the alicorn was holding was not one she recognized, but it was a kind of book that was immediately obvious. The front cover bore runic markings that she didn’t recognize, curling and forked symbols—she couldn’t grasp their meaning, but she had the distinct sense that they were reminiscent of grasping hands. It was bound in what looked like genuine leather, an extreme rarity in Equestria, pitch black and tanned to a glossy texture. The title was embossed in golden letters: On the Malleability of Flesh.

Bibliophiles like Sunset Shimmer and Twilight Sparkle often couldn’t resist a new book, but there were some books that were immediate red flags.

Sunset Shimmer snatched the book from her hands—physically (and none too gently); some books like these could react to the mere presence of magic. She snorted and shook her head. “What does Twilight think she’s doing, leaving out tomes of eldritch wisdom where anypony can find them?” She glanced back toward Twilight Sparkle (not to be confused with the Princess she had been referring to) and asked, “Where did you find this?”

Looking nervous, as if she had been caught committing a crime, Twilight Sparkle looked over her shoulder toward the table, and then shrugged. “It was just…in among all the others. Is it…dangerous?”

“Probably,” Sunset Shimmer replied promptly. There was a different kind of sensation running through her skin as she traced her fingers over the leather cover: tingling, prickling, bristling, hairs standing on end, adrenaline stirring within her. Fear, anticipation. But there was still some excitement there. She couldn’t quash her own curiosity entirely. She also had to remind herself, though, that that could very easily be an infectious thought being forcibly inserted into her brain by the enigmatic artifact.

“Oh…” Twilight Sparkle would do this cute thing when she was anxious or embarrassed where she clasped her hands in her lap and bit her lip. The effect was a lot different when she had breasts bigger than her head, squeezed between her arms, and was also naked.

Sunset Shimmer stared at her pointedly and said, “You didn’t read any of it, did you?”

“No.” The alicorn’s answer was prompt and unwavering—she almost certainly wasn’t lying. But the anxiousness was still there. Desire burned under the surface.

“But you want to read it.”

Her gaze cast downward.

The unicorn rubbed her temple. “Twilight, sweetie, look, I know that we’ve had all kinds of friendship lessons about ‘don’t judge a book by its cover’ and stuff like that, but sometimes you have to literally judge a book by its cover.” She held up the heavy book for emphasis. “Don’t you have stories about stuff like this in your world? H.P. Lovecraft, Necronomicon, all that crap, doesn’t that mean anything to you? Sometimes just looking at something like this can be enough to make bad shit happen! Princess Twilight told me that her Rarity found a book like this one time and she went on a rampage in Ponyville!”

Sweat trickled down Twilight Sparkle’s brow, and not the kind that happened when the two of them were intertwined in throes of passion. Her eyes quavered behind her glasses. She was acting like a student who was fumbling for an answer they didn’t know, likely the first time she had ever experienced something of that sort in her life. Finally, she stammered, “Look, I…I know this is going to sound weird, but…there was something I’d been…thinking about…”

“Uh-huh.”

For a few seconds, Twilight Sparkle looked downcast, uncertain, struggling to sort her thoughts, to find the words, and eventually she blurted out, “I felt guilty.”

Sunset Shimmer quirked an eyebrow upward. “What for?”

“For these!” The lavender mare gripped her breasts and heaved them, wringing them in her fingers, yielding to her touch. “I didn’t ask for them to be so big! They just…are!” She let go, leaving them to flop back into a natural position, pert teardrop ovoids, and her ears drooped. “It’s not fair that I’m so much…bigger than you.”

The unicorn’s carnal excitement was tamped down by guilt of her own and—she would be ashamed to admit—a spike of lingering bitterness. While she was happy for her marefriend enjoying herself, there still remained the disappointment that that size wasn’t something she could have for herself, the weight hanging from her chest, the pliant flesh yielding surges of stimulation at the slightest touch.

“Okay,” she said, breathing a sigh, “what does that have to do with this?” Again she held up the book and tapped the eerie black cover.

Once more Twilight Sparkle visibly fumbled with her internal thoughts before she spoke. “Well…it was weird,” she muttered, pondering, her brow furrowed, “I was looking through the books on the table, and…I just had this…idea, all of a sudden, and I wondered…if I might be able to find any kind of magic that would let me…make your boobs bigger.” The alicorn seemed to try to shrink, to make herself unnoticeable. She might not have realized the way her wings folded about herself and her tail curled around her legs.

“Oh.” Sunset Shimmer blinked. “Uh…yeah, there are spells like that.” She had to suppress the urge to grimace; growth spells, while indeed real, had a particular effect that wasn’t always the most pleasant, usually causing one’s assets to feel tight and uncomfortable, worse if not cast properly. For as much as her size envy had been flaring up, she wasn’t certain that this was an avenue she wanted to explore, but nonetheless she responded, “I could’ve helped you find some if you really wanted to try that.”

“I-I’m sure you could have…but…” Her eyes widened as she stared straight ahead. “That was when I saw it.”

“It?” Sunset Shimmer gestured with the book yet again, just to be clear.

“It was just…right there in the pile,” Twilight Sparkle said, shaking her head, “right after I thought to myself about breast expansion magic, I just felt this…pull, like I was supposed to look there. It was so…striking, how could I not want to look at it?” And when she saw that Sunset Shimmer’s disbelief was mounting further, she added, “And you’re right, I…I did think it looked…ominous. That was the whole reason I asked you about it, I wanted to…check and see if you might know anything…if it was dangerous.”

“At least I can be glad to know that you’ve got some sense in you after all then,” Sunset Shimmer groused, letting out a heavy sigh. One more time she looked at the cover of the aged book, her thumbs rubbing at the intricate markings. “The malleability of flesh, huh?” she mused aloud, “Must be about some capacity of organic transmutation. There could be something for tits in here. And who knows how much else.”

She glanced up from the black and gold cover at Twilight Sparkle. She was anxious, nervous, embarrassed, and ashamed. The one thing she wasn’t, though, was backing down. She still had her gaze fixed upon the book, and there was determination and longing etched into her face in equal measures. It was in her nature, of course, to be relentless in the pursuit of knowledge, to explore the unknown, as it was for her Equestrian counterpart. Or maybe she was just really fixated on the idea of her partner having bigger breasts.

So Sunset Shimmer finally declared “Fuck it” and opened the book.

There were no immediately obvious repercussions to this action—no flashing lights and surging magic, no otherworldly portals tearing open the fabric of reality, no tentacles spilling out to grasp at her, no ineffable eldritch knowledge that caused her brain to melt out her ears. The first page reiterated the title of the book and there was a convenient table of contents on the second. “Huh,” she remarked in plain bemusement.

“What’s it say?” Twilight Sparkle asked whilst sidling next to her, their broad hips and bosoms mashed together.

Sunset Shimer skimmed over the next few pages, reading the introductory text. “The origins of equinity being taken for granted, painstaking research, dedication to truth…the usual garbage peddled by new age spiritualism hucksters.”

“But does it have anything about spells?” Lavender hands were tentatively reaching toward the book, eager to take it and lead the research.

With a beleaguered sigh, the unicorn flipped back to the table of contents and traced along the list with one finger. “Introduction, The Call of Flesh, The Secrets of Equestria…What the Princesses Don’t Want You to Know…The Supplication of…” Her muzzle scrunched up at the notion of attempting to pronounce a name that was sorely lacking in vowels, and she skipped further down. “Here: Practical Applications. That sounds promising.” She dug into the pages and turned about halfway into the tome. She landed exactly on the section she wanted (years of bookworm behavior gave one an uncanny ability to know exactly where to open up a book to find the page they were looking for).

“Abdomen?” Twilight Sparkle remarked upon seeing the header that marked the first section of the chapter.

Sunset Shimmer was looking at the first listing under the header. “Fill stomach with substance of choice…?”

“It must be organized based on the part of the body that is affected,” the alicorn murmured, “so abdomen means the midsection region.” She grimaced. “Who would want to give themselves a fat gut?”

“Some cultures have different ideals of beauty, Twi,” Sunset Shimmer replied with a shrug. “And some people just have kinks for that.”

They browsed through the pages of spells. There wasn’t a section labeled “breasts,” so they had to dig deeper, passing by numerous other groupings in the process.

“Well we’ve got plenty of options for making buttocks bigger from the looks of it,” Twilight Sparkle said and smirked, “we’re going to need to balance things out on the bottom once we’re done anyway.”

“Maybe your ass is the one we should make fatter,” Sunset Shimmer replied, sticking out her tongue, “you spend so much time sitting on it.”

“H-hey!”

There were some sections that were what they might have expected and others that were particularly unusual. Despite the immediate urgency of the task which was before them, they couldn’t resist lingering on the text at random intervals.

“Cranium?” Sunset Shimmer exclaimed out of the blue.

“What, so…the head?” Twilight Sparkle asked.

“How’d this weirdo get enough spells to fill thirteen pages with this stuff?”

“Kinks?”

“I guess, but still…”

And eventually (after moving to sit at the table instead of standing) they found what they were hoping for.

“Mammaries!” Twilight Sparkle blurted out, pointing to the text on the page, “That’s gotta be it!”

But Sunset Shimmer proceeded to thumb through the proceeding pages upon pages upon pages. “That’s a lot of titty magic,” she mused. It was easily the largest section they had seen thus far, spanning over more than fifty pages.

“Well, at least we know we’ve got options,” Twilight Sparkle added optimistically.

The tawny mare offered a hopeful smile before she turned her attention back to the book, and she blindly put her finger upon a random listing. “Blessing of Plenty…increases rate of milk production to the extent of…feeding a whole village for a month?!”

“O-oh…” The alicorn covered her mouth, obscuring her expression and her blush.

They browsed the pages, in the process finding that they did indeed have plenty of options, but many of them were a great deal more than they were expecting. Some of them were truly bizarre in their effects, to an extent which Sunset Shimmer wouldn’t have expected to be possible. It seemed that the malleability of flesh was in fact a great deal more varied than she once thought.

“Increase tactile sensitivity, thus enabling what is described as an orgasm of the breast…kinda hot, I suppose…”

“Alter mammary glands to produce different substances? Do you think we could make ourselves lactate soda?”

“Assimilate organic matter into—oh, eugh!” Sunset Shimmer’s stomach lurched just at imagining what was described. She felt tingling and bristling in the skin of her bosom, the phantoms of insects crawling over her.

“Hey, Sunset,” Twilight Sparkle muttered, “what about this one?”

“What?” She’d take anything at this point.

“Propagation of Desire,” she read, directing their attention to the title in question. “Summons a spirit of lust into a willing vessel, making them more desirable to their peers.”

Sunset Shimmer stared skeptically at the words. “That sounds…vague. What does it mean to be ‘more desirable’?”

“Well, if I desire for you to have bigger boobs, then that should mean it will make that happen, doesn’t it?” Twilight Sparkle placed a hand on her, starting on her shoulder before sliding down to the base of her breast, and she grinned.

“I dunno, Twi…” The phrasing didn’t sit right with her. What did “willing vessel” mean? It seemed to imply that the spirit, whatever it was, would be occupying her body. To what end could that lead?

“Oh come on.” Now the alicorn outright pulled the book closer toward her, bringing it up to her chest so she could wrap her arms around it—another of those cute gestures that were framed a lot differently when she had armfuls of titflesh. “We’ve been looking long enough; can’t we try it?”

Sunset Shimmer managed to crack a smirk. “Are you really that impatient for my tits to be bigger?”

“W-well…” Twilight Sparkled blushed again.

“You’re so hungry that it’s not enough for your own to be so huge?” Now she reached over and pinched a fold of purple mound between her fingers, and the mare yelped and they both giggled. The humor and horniness of the moment buried the doubts, just a little. “Okay, fine,” she eventually admitted, however reluctantly, “but are you really sure you want to try casting something like this?”

“It can’t be that hard, can it?” She looked at the pages again, this time the instructions for the spell in question. “All we have to do is…inscribe a magic circle to act as the conduit for the spell.”

“The usual summoning circle shtick, huh? Alright, the Princess should have left chalk somewhere.”

Sunset Shimmer left Twilight Sparkle to study the spell while she went to search the castle for the magical supplies—and still relishing in her nudity; even if the building interior was hardly a public space, it was nonetheless freeing to be so brazen after her time in the human world. When she returned with the chalk, she offered to draw the circle, but the other mare insisted on doing it all by herself. To her credit, she did an admirable job, using both her hands and her magic to get every detail down to the utmost precision. The only difficulty arose when she first knelt down to the floor, wanting to get close to make sure the runes were correct, only to rise and discover white smudges across her bosom where her hanging breasts had brushed across the ground. Further inscriptions had to be made with the consideration of using levitation as a magical brassiere.

And all the while, Sunset Shimmer watched, and between being impressed with her marefriend and protégé’s progress and ogling the swaying motions of her rump, she was puzzled. She couldn’t recognize any of the markings used on the circle either, the same forked, grasping shapes that were on the cover of the spell book. Its existence remained puzzling to her; perhaps it wasn’t as dangerous as she first thought, but its presence in such an open part of Princess Twilight’s collection was still unusual.

It just didn’t seem right no matter how she thought about it.

But then she looked down at her chest and imagined the golden mounds extending twice or thrice their current breadth, and suddenly those thoughts didn’t matter anymore.

“Alright, it’s done,” Twilight Sparkle announced once she was satisfied, after double- and triple-chceking—lust couldn’t entirely override the need for perfectionism. The intricate network of markings gave the impression of a spider web; it was almost uncanny how close to the diagram in the book she had managed to get for what was about to be her first real spell. A good thing, since that meant less likelihood of something going awry.

“Great job, Twi,” Sunset Shimmer replied with a nod, a smile, and a clap on the mare’s cheek for good measure, fingers clasping the plush, pliant flesh. She purred back in response and leaned against her. “So you’re all ready for this? It’s just my body on the line, no pressure.” Perhaps she should have been more concerned for herself, but, if anything, she was more worried for how Twilight Sparkle would feel if something were to fail catastrophically, setting back her attempts at progress.

“It’s going to be your body on the line if you don’t get your butt in there and let me cast the spell,” Twilight Sparkle whispered to her before then slapping her on the ass in turn, and Sunset Shimmer was sufficiently taken aback that she yelped and stumbled forward, but then they both laughed.

With the utmost care not to step on any of the chalk markings and necessitate yet more fiddling, Sunset Shimmer moved into the center of the circle, where there was an open space which she could fit her hooves into. An electric tingling coursed through her, a cocktail of excitement and wariness, teetering on the edge of a metaphorical cliff, looking down at water with jagged rocks jutting up from the surf (in her mind’s eye, though, the rocks had a distinctly phallic look).

“Okay, so…just focus,” Twilight Sparkle muttered to herself whilst peering at the pages of the book, holding it up in front of her face. “Channel magic through the circle…and that should do the rest.” Her horn shimmered with magenta light, and after a few seconds the same glow began to rise up from the floor, the white chalk suffused with the color of her magical aura. It produced an ambient force rising upward, and Sunset Shimmer’s mane and tail billowed around her, as if she were submerged in water, wreathing her in crimson and gold. In spite of this form of magic being relatively commonplace, she felt a form of marvel welling up within.

Then, dimly, the unicorn became aware of movement beneath her. She looked down and saw the markings of the summoning circle twisting about. The runes—the hands—were converging upon her.

“Twil—”

She gagged. Her further attempts at protest were silenced in her throat. Her jaws were locked open, stretched painfully, unable to close on account of being filled to capacity. There was something invisible forcing its way into her. There was a distant muffled noise that might have been Twilight Sparkle screaming her name. Her fingers twitched with the ghost of an impulse to reach up and grasp at the open air, but her arms wouldn’t move far enough, locked at the joints. At least that same paralysis was keeping her legs stiff enough that she wasn’t falling over. Her eyes burned while her innards strained.

And then the presence was gone, her mouth and throat free so she could shriek her horror into the world, but instead all she could manage was a choked gurgle as she tottered backward. She might have collapsed were it not for an intangible aura which manifested around her and held her upright. “Sunset!” Twilight Sparkle was before her momentarily, her shocked, terrified, on-the-verge-of-tears face mere inches away. “What’s wrong, what happened, are you hurt?!”

“I…” The unicorn clapped a hand to her head as she felt it throb like the onset of a migraine. Her thoughts were jumbled, her immediate memories covered in a fog—she remembered that the two of them had been working on casting a spell, and something had gone wrong, but she found herself unable to recall the exact details of what had happened. She thought she should have felt ill, and yet she didn’t, so surely there was nothing to worry about, but regardless she still found herself worrying. “I…don’t know,” she eventually muttered. “What did you see happening?”

“You were…I don’t know, you were twitching, and you had your mouth open, and you looked like you were in pain!” Twilight Sparkle stammered back. “Oh, this…this is all my fault, I shouldn’t have made us do this, I should’ve known that I wasn’t—!”

“Shh, shh.” Sunset Shimmer quieted her, a motion that was accompanied by reaching around for a hug. She hoped it was soothing for Twilight Sparkle because it was helping her just as much, giving her an anchor to keep her in place amidst this sudden surge of intensity. The warmth of their hearts beating together, gradually slowing to a calmer pace, mixed with the sweet fragrance of their bodies. For once, the cushy softness of their breasts mashing together between them was a pleasant reassurance more than it was arousal. “Don’t put yourself down for this,” she whispered, “accidents happen.”

Twilight Sparkle sniffled back and muttered, “I just wanted to do something nice for you.”

“Well, look on the bright side for now, nothing really bad happened.”

(there was a sensation within, brushing against the interior of her ribcage)

“I just…wanted your boobs to be bigger so we could—”

Pressure spontaneously bloomed into being between the two mares. There were gasps of alarm as they found themselves being pushed apart, but there was little that could be done to stop their separation, wobbling as they stood apart. Sunset Shimmer was sufficiently taken aback that the pressure which mounted inside her went unnoticed until she saw the way Twilight Sparkle’s jaw dropped, staring in awe, gaze listing downward, which prompted her to look down as well. She thought she must have had the same expression at that point.

Where before the unicorn’s breasts were about the size of her head, pert globes which filled the palms of her hands and then some, they were now utterly enormous, maybe three or four times larger, if not more. They extended to the sides, far past her shoulders, and jutted out in front of her just as much. She had to lift her arms around the swollen masses in order to see them again, and in doing so she saw that their reach would scarcely be enough to contain her at this size, the slender limbs like twigs in comparison. She tried to speak, to voice her amazement, but no words came, all she could do was place her hands on her bosom and feel it—pressing, squeezing, groping, kneading. The supple flesh felt real in a way that she had never experienced from magically enhanced bodies in the past, and oh so tender as well. She distantly heard herself moaning, a low croon uncannily like that of a cow, while she caressed herself.

And then there was another pair of hands grabbing at her, lavender pressing into gold. “Oh…w-wow, it…j-just…” Twilight Sparkle muttered absentmindedly, staring, nearly unfocused. Of course, in the process of getting close enough to do this, both of their prodigious busts came into contact, mashing into each other, rising up as they compressed, like the meeting of tectonic plates. The bare, sensitive skin of the nipples kissed, and they each shuddered in a tremor of pleasure. Neither especially noticed that Sunset Shimmer might have actually been the larger one now; the difference between them didn’t matter nearly as much as the notion of “bigger.”

“T-Twilight,” Sunset Shimmer gasped between moans, “how…how did you d-do this?”

Twilight Sparkle stared back, nearly blank for several seconds before she refocused. “I…don’t know,” she admitted, “the spell said that…the spirit would take charge of the transformations once it was summoned into a vessel.”

“The…spirit…” she repeated, brows furrowing. The pieces were coming together. The sensation of being entered—that was the entity, this spirit of desire, joining with her body. It was in her. Still in her, presumably. The aches and irregularities of her body suddenly felt all the more pronounced; anything could be a warning sign that there was something terribly amiss. And yet, all the same, so long as there was stimulation coursing through her, she couldn’t bring herself to panic. When she looked into Twilight Sparkle’s eyes, she saw the yearning reflect back on her, the equal desire which both of them carried in hope for an outcome such as this.

“Thou lovest her, doth thou not?”

“Yes,” Sunset Shimmer blurted out.

“What?” Twilight Sparkle asked, blinking.

“Then thou wouldst doeth anything for her?”

“Anything, absolutely.” The unicorn’s heart was racing.

“Sunset, are you speaking to someone?”

“So thou shalt become everything for her.”

She nodded her head emphatically.

An image flashed within her mind. There was a tawny mare who must have been her. There was a particular focus on the chest region. There was so much of it. There could have been more.

It was accompanied by a sense of…projection. The image was not a product of her own mind—it was coming from elsewhere.

The pressure burst in her chest again. She only had a moment in which to register that this was different, more intense, pushing forcefully through flesh and bone, as if something were about to pierce through her sternum. The urge to cry out morphed into a carnal groan as nearly the same scenario as before played out, her chest billowing outward in a surge of mass which strained the space between the of them even further. This time, however, while her own strength faltered, Twilight Sparkle continued to hold onto her, keeping her in place. And, additionally, this time when they looked down at themselves, they were met with a sight that was even more unusual.

Sunset Shimmer had nearly expected to see yet another exponential growth spurt, breasts which might be the size of beach balls, beanbag chairs, or weather balloons, spilling out before her and reaching past her waist, knees, maybe even all the way to the floor, with a deep canyon of cleavage between them which she would be able to nestle her marefriend within. The idea was electrifyingly titillating on a primal level. Instead, however, it didn’t seem like the span between them had actually increased much at all.

What was really different, she realized, was that instead of there being an enormous span of cleavage, there were now two clefts in the collective mass which extended from her chest. Sunset Shimmer cupped her arms against the undersides of her left and right breasts and hefted their (considerable) weight upward, but in doing so there was no support for the new middle breast. She found herself entirely at a loss for words that could accurately describe her feelings regarding this turn of events.

A good thing, then, that Twilight Sparkle butted in, muttering, “Oh, I…didn’t think that would…” She backed away, separating so that she could get a better look head-on. The unicorn’s three breasts sagged to natural positions, bobbing slightly with her breathing; the new one appeared to be the same size as its partners, crowding the space that was allotted for them all the more. Her eyes quavered with concern, but there was a faint curl at the edges of her lips.

“T-Twi?!” Sunset Shimmer sputtered in the midst of trying to find a way to encompass all of her newfound girth, “Did…did you—?!”

The swelling, pushing pressure made itself known once more—three times over, at that. Exhilaration flashed through her. Then it exploded outward, yet more tactile information washing over her brain, flesh exposed to open air and rubbing against itself. This time, without the support of another mare in front of her, the inertia pulled on her in a more significant fashion, the outward expansion nearly knocking her backward. Her breasts were pushed from below, knocking them upward in one big arc, and when they resettled they were now rising higher than before; even with her gaze fixed straight ahead (at a lavender mare who was growing increasingly flustered as she watched all this transpire), she could see the upper slopes of the furred hills cresting into view. It was because her breasts were resting upon a second row of three breasts which had sprouted into being directly beneath them.

“Twi…l-light!” the unicorn implored desperately amidst the struggle to keep herself upright. She still tried in vain to heave up all of her sextuple-bosom, mass spilling about, but now the awkwardness was combined with sheer weight, pulling on her to an extent she was wholly unfamiliar, threatening to bind her to the floor.

“It…is this…am I doing this?!” Twilight Sparkle asked aloud in shocked disbelief. She was alarmed, but her cheeks were only turning redder with every passing second.

“It’s responding to…t-to your desire, Twilight!” Sunset Shimmer cried back before her voice hitched into another sharp moan; she could barely reach her nipples, but just touching the areoles prompted a wave of stimulation. The vision of herself floated in her mind, and dimly she thought that she was seeing herself from the other mare’s point of view, albeit distorted. “It’s m-making your wishes into reality! Ah…although…” In spite of everything, she was able to laugh, a hollow knocking in her throat. “I g-gotta say, Twi…when we started talking about kinks, I didn’t think you’d be this kinky.”

That made the alicorn blush so hard that her face nearly turned magenta. “I…um…well it’s just…all these spells in this book…!” She picked up the spell book again, having been nearly forgotten in the midst of all this chaos, and looked through the pages once more. “There were so many, and…and while you were gone, I c-couldn’t help…th-thinking about them…l-like this one—”

She opened to a particular page and pointed to one of the entries, then came closer so that Sunset Shimmer could read it. She promptly sputtered, “Mammary…M-M-Multiplication?!”

As if on cue, there was another volatile rush of sensation. The unicorn could only wince as a seventh, eighth, and ninth breast sprang into being, and the weight grew all the more. A wall of mammaries were grafted to her front, and now she was really having a hard time seeing over them, having to crane her neck to see Twilight Sparkle and that damned book. The projected image in her mind offered her an outside perspective, showing absolutely none of her torso visible anymore, obscured from the waist up, a series of balloons perched on top of a pair of legs, a three-by-three arrangement like some bizarre tic-tac-toe board.

“Stop!” she wanted to shout at the top of her lungs. Or, at least, a part of her did. Even if she weren’t already too inundated with sensory overload to do much of anything, the greater part of her would not have resisted the temptation for yet more.

So instead she gasped, “T-Twil-light…th-think of…something else!”

“Something else?” she repeated quizzically, looking up from the pages of the book, “like…wh-what?”

And Sunset Shimmer grunted through the stifling arousal as she fumbled with her breasts. “A…ah…!” For a moment, she thought she was going to blurt out, “All of it!” Instead, though, she said, “Anything! Whatever you want!”

“O-okay!” Twilight Sparkle flipped to a random page and scanned across its contents, settling on a random spell. Perhaps she was mulling over what she planned to do, indecisively weighing her options. In the mere act of thinking about it, though, it came into reality.

Sunset Shimmer felt her whole body tighten, her skin too small to contain her. Her fingers clenched and her arms curled, and she felt strength building up within her, a raw, physical strength that was unlike that which came from magical potency. A guttural growl rose in her throat as every movement suddenly became less laborious than it had been moments before—even in the act of breathing, she felt the way her back rippled and strained as her lungs pumped air, momentarily allowing her to imagine the flapping of wings. The weight of her multiplied bosom was far less of a concern now, a burden which she could effortlessly carry. She lifted her arm for inspection and wasn’t too surprised to see that the once-slender limb was now bulging with cords of sinew underneath the surface of fur and skin, musculature that would have shamed any of her more athletic friends (and she herself was already more athletic than her purely nerd-inclined marefriend). She glanced further down, and although her breasts obliterated so much of her view she could at least see the tone in her shoulders and chest, and she reached around to place her hands on her stomach, to feel the definition of her abs.

She turned her attention back toward Twilight Sparkle, only to discover in doing so that the alicorn had shrunken considerably before her—no, of course not, it had to be the other way around; she had grown taller, by at least half her height over again, looming above her surroundings, even able to see over the tops of the library bookshelves—and she smiled sheepishly up at her. “Heh…I guess the…Amarezonian Beauty spell really wasn’t lying about the…beauty,” she said in a demure squeak.

“You’re r-really…getting into experimenting, huh?” Sunset Shimmer huffed back while flexing. She wasn’t sure that she looked any less ridiculous, but she certainly felt a lot more capable now. The muscle strength might help her with whatever changes might be coming further down the pipeline. It was also helping to build the arousal which was burning in her loins, drooling in rivulets between her thighs. “I wonder…what you were planning to do with a mare who looks like this.”

Twilight Sparkle held the spell book close to her chest and made a lopsided grin. “Um…well…” One could almost see the steam wafting from her ears as her brain whirred with activity.

There were a couple loud pops. The changes which Sunset Shimmer felt were, relatively speaking, not so significant, but it was immediately very noticeable. There was no way for her to not notice the mound which had suddenly risen up past the end of her muzzle, glossy dark crimson surface glistening faintly. She opened and closed her mouth and the mound wobbled, along with its twin on the lower jaw, and they made a wet smack when they came together. She could have thought of a lot of things to do with such fat lips, though she could have done without yet more obstructions to her ability to see anything.

But all of that kept her distracted long enough that she didn’t notice what was happening further down in her body until a pang of arousal forced a sharp gasp from her newly swollen lips. The space between her legs was growing crowded, but any attempt to squeeze the appendages together only elicited a surge of stimulation that nearly brought her to her knees. She couldn’t possibly have seen what was happening to herself, but thanks to her connection with Twilight Sparkle she was able to get a better understanding. Her groin was no longer a smooth surface with a puffy slit, instead outright bulging outward, pressing into her thighs on either side and fighting to take up even more space. The opening gaped, presenting the fleshy folds within like a flower opening to the rays of the sun, and the way it undulated as it winked gave the impression that it was breathing. And the flow of viscous nectar from within her had only become even more profuse, splattering over the floor. The unicorn groaned as she reached to sate her mounting desire, but the shudder of pleasure that wracked through her from even the slightest touch made her recoil and writhe in ecstasy. “T-Twi…” she groaned, eyelids fluttering.

But even though her vision was blurring, losing focus, she could see clearly in her mind the way the vulva was not merely swelling but appearing to zoom in, coming closer, closer. And then Twilight Sparkle’s hands pressed upon her, gripping heaps of the taut, tender flesh, squeezing, kneading. Sunset Shimmer cried shrilly, staggered, tripped over herself and her own unwieldy weight. Mid-fall, however, a new impetus sprang into being, manifesting with a dizzying speed; the ballooning pressure in her rear, billowing outward, came and went so quickly that she nearly didn’t notice it. The impact came with a thunderous thud, shaking the room, knocking several books from the table and shelves, but it was not as harsh as she had expected it to be, the landing soft and cushy, as if she had landed on balloons, yet it was definitely the floor which she felt beneath her rump. Twisting around—numerous breasts knocking against each other in the process—she peered behind her and saw two vast hills of orange that swelled out to the rear, red and yellow suns printed on their sides, her tail nestled in the valley between them. She had her built-in beanbag chairs after all, positioned so that she could sit on them wherever she went.

“I told you we had to make your butt bigger too,” Twilight Sparkle called to her, gently teasing, from the other side of the wall of breasts. With Sunset Shimmer sitting down, the disparity in height between them was lessened somewhat, but it also had the effect of unconsciously spreading her legs, further presenting the gash between her thighs. The unicorn saw Twilight Sparkle approach an opening of flesh, a damp, salivating cavern, which she could have buried herself in. She had the impression of the hands reaching in, toward the quivering folds, before she actually felt them, and the swells of exhilaration which subsequently ran through her, once more reducing her to squirming and hysterical moaning. She could only dimly hear the alicorn musing, perhaps more to herself, “I never could have imagined there was so much we could do with this magic. Our bodies are so…elastic, it’s like they can become anything.” That was before she pushed her head in and started nuzzling and licking the vaginal walls.

Sunset Shimmer could only respond with continued howling, jiggling, and gushing. The bespectacled mare’s touch wasn’t particularly precise, her technique unrefined, but there wasn’t much need for that when the flesh was so sensitive that even the slightest touch prompted spasms of agonizing pleasure. Juices poured unbidden onto the floor and squirted in fits and spurts onto Twilight Sparkle, steadily drenching her in sexual excess. It was only a matter of time, though, before she found the clitoris, a swollen bulb the size of a basketball, oh-so-tantalizing to reach out and grab. The yearning and curiosity which radiated from her were blazing in intensity.

So of course she pressed her muzzle against it and gave it a kiss.

The unicorn roared as she orgasmed. A flood of cum erupted from her vulva like a broken water main, washing over Twilight Sparkle, though the clamping of the folds on her body held her in place like the jaws of a bear trap. Sunset Shimmer rocked back on her mattress of buttock meat and squeezed with her muscular arms against the sides of her breasts, three columns mashing together, and her aching nipples began to leak as well, a ninefold battery of milk which contributed to the white deluge. She kept pawing at herself, shaking and quivering and throbbing, lips parted and tongue lolling out, long after the high had subsided, after the rush of fluid had ceased and Twilight Sparkle had been released, leaving her to collapse and pant for breath as well, the adrenaline having faded. She looked up at the giant, distorted mare, panted white across much of her front, her glasses askew and her mane matted, and she whispered, “W-wow…”

Something stirred within Sunset Shimmer, something not entirely physical. It felt like it was trying to regurgitate itself.

“Thine partner hath been satisfied. Our power is no longer needed.”

“No,” she snarled back.

The entity seemed genuinely taken aback by this response, as if flinching at her intensity.

“We’re not done yet,” she asserted venomously.

After some seconds of silent deliberation, there was a reply.

“Thine desire is exceptional. Very well. Do as thou wilt.”

“Sunset?” Twilight Sparkle’s voice called for her again. “D-do you…want to do something else?”

There was a premonitory shudder in Sunset Shimmer’s spine, rolling up her neck to her brain. She sensed the impetus that was coming from the alicorn, the new desires which would take effect upon her body in moments. That wouldn’t do; she had new plans in mind. It took but a thought to sever the connection binding the spirit to its summoner and to reattach it elsewhere. In particular, to herself.

“Yes,” she crooned back in a prolonged, hissing note, voice rumbling while her bones shifted and stretched, exhaling a breath of hot vapor.

The unicorn rolled forward, far enough that her breasts were no longer obscuring her view of the lavender mare before her, letting her see as her expression morphed from dreamy uncertainty to shock. Her hands slammed down on the floor one after another, nails scraping over the crystalline surface; the muscle of her arms had become offset by their length, extended to nearly double what they had been before. This allowed her to stand on all fours and still keep her array of dangling breasts off of the floor, though the same was not so for her distended groin, vulva extending down to her hooves to kiss the floor and fill the span between her legs. The smaller mare stepped cautiously backward, but she craned further forward on her neck to close the distance, not even thinking about it as vertebrae popped into existence one by one. Her plump lips parted in a toothy smile, far more jagged than a pony’s mouth should have been.

Twilight Sparkle could only watch and stare all of this unfold, frozen like a deer caught in the headlights of an oncoming vehicle. She stared blankly, jaw hanging limp, but there was no denying the marvel that shimmered in her eyes or the tint on her cheeks.

“Here, let’s try another trick,” Sunset Shimmer said with a throaty chuckle. She crawled closer, looming, until her breasts were directly over Twilight Sparkle, still leaking a steady trickle of milk from her engorged nipples. “Were you still wondering what it would be like to change what we lactate?” she asked, though she didn’t bother waiting for a response. The warped pony squeezed her bosom again, like nine tubes of toothpaste lashed together. Streams of milk spilled out at once as she began kneading, and Twilight Sparkle gave a cry of delight at first, reveling in the excess and hedonism, but rapidly something changed, once the glands had been altered and all the leftover fluid had been ejected. The white rivers changed their consistency, turning clear and viscous, and a bitter, acrid smell filled the air.

She sputtered as the gel clung to her, matting her hair and fur (though it had the additional effect of washing away the stains on her body). Her skin tingled in waves of numbness, seeping in deeper and deeper. She tried to wipe it away, but that only caused her arms to become tangled in it as well, and she didn’t think she could peel it off with her magic—not that she had the focus necessary to use magic. She had to clench her eyes shut to keep the goo out, and she was hesitant even to open her mouth to speak, but she had to, to voice her concerns. “Sunset! P…p-please…”

There was a twinge inside her.

“Please fuck me up!”

The words resounded in her skull, her own voice alien to her.

“It’s okay, Twilight,” Sunset Shimmer replied to her distantly, “we must admit our desires if we are to accept them.”

Twilight Sparkle wanted to protest—no, she didn’t want to, it was merely a feeling, an urge, an instinct born in her out of obligation to her sense of normality. A desire for something so senseless had to be wrong, a sign that she was out of her mind. But if there was one thing that was forever going to be intrinsically a part of her, it would be her thirst for knowledge and the quest for understanding. In the time since arriving in Equestria, that quest had morphed into a form that was rooted more in experience than research: the experience of casting magic, the experience of passion and longing, and the experience of the mutability of flesh.

She had taken so much excitement in the process of watching Sunset Shimmer transform and deform, swelling out of control into a parody of herself. She had felt the thrill of knowing that it was something she was influencing, however indirectly, a sign of her magical potency far more extreme than blowing up a coat rack or levitating books could have been. She had wanted to do so much more with it.

But, under the surface, what she truly desired was to have it flipped back on her. She wanted to feel the irrepressible power warping her very structure. She wanted her normal to be eroded ever further. She wanted to be more.

She could accept that.

She opened her eyes.

The light in the library seemed particularly saturated now as Twilight Sparkle held her arm up in front of herself. The translucent slime was sloughing off of her while the flow gradually trickled to a stop, but its glossy sheen remained on the skin underneath. She no longer had fur, she discovered, or even hair; her skin was smooth and uniform, and when she pressed into herself, rubbing her palm along the length of her arm, the surface dragged and clung, producing a squealing noise like rubber or latex. She looked up at her mane and touched it gingerly, and it bobbed, the hairs fused into a curtain-like structure, indigo flaps striped with purple and pink, curling around itself in the back where she had tied it into a ponytail previously. Unavoidably, she prodded at her breasts, squeezing the swollen globes together, and she felt that they were a tad firmer, their flesh less pliant. No less sensitive, though, despite seemingly being made of inorganic material, and a long sigh of contentment unfurled from her while she planted a palm on her rump, pushing in, just to be certain of it.

“It looks like we can change a lot more than just our secretions,” she mused, laughing. There wasn’t even a hint of a stammer left in her; she had nothing to be uncertain of.

“Like you said, our elasticity is unmatched,” Sunset Shimmer replied, chuckling as well.

“I didn’t expect it to be so literal.” Twilight Sparkle had a wholly reasonable urge to look at herself, to observe what she had become, but she found that that wasn’t necessary. She could see herself in her subconscious thoughts, and she understood immediately that this vision was something which Sunset Shimmer had placed there for her own benefit, an outside perspective, however hazy it might be (and bearing a lip that was rising into the lower periphery of the figurative frame).

“All that’s left is to do a stress test,” the giant unicorn remarked sensually, lapping at her lips with a long tongue.

“A thorough test,” she asserted pointedly, grinning back.

“Exactly what I had in mind.”

Sunset Shimmer descended, converging with her elongated extremities upon the mare before her. Spindly arms groped at Twilight Sparkle, hands broad enough to squeeze huge swathes of her breasts and buttocks, who in turn reached up to caress the long neck just under the jaw. They only gazed at each other longingly for a scant few seconds before they kissed—a rather one-sided exchange, with Sunset Shimmer not only maintaining an iron grip on her but also smothering much of her face with her pillowy lips, but that wasn’t going to deter either of them. Twilight Sparkle reciprocated with the sheer intensity of her fervor, passionately pushing back and working with her muzzle to knead the glossy mounds that were threatening to bury her, smearing their painted coat across her synthetic skin.

But then she noticed the way Sunset Shimmer was breathing, exhaling in deep huffs. Her throat bulged in a progressive rhythm, something pumping up from within her. She felt like speaking, to ask what was happening, but she could do neither that nor pull out while the dark lips were clamped onto her—again, not exactly that she wanted to; the lingering adherence to normalcy had to be quashed as soon as possible. The exhilarating anticipation which welled up inside the alicorn only made her all the more impassioned in her lovemaking. As if being aware of this desire (which was very possible), Sunset Shimmer’s body lumbered closer, catching up with her extended appendages, and Twilight Sparkle was all too quick to reach out for two nipples to grasp onto.

It was a short-lived thrill. The contents of Sunset Shimmer’s throat poured out into Twilight Sparkle, and she nearly choked before she remembered to swallow. Her own body bulged in turn as the substance passed through her mouth and esophagus and stomach, distending along the path of her digestive tract. She couldn’t identify what she was being fed, neither solid nor liquid nor gas, an imperceptible presence—the very concept of “filling” being stuffed into her. She could feel that her body was ballooning outward each time, starting in her stomach, fuller than she had ever been after any Pinkie Pie party and then ever further, before funneling outward, breasts and buttocks, arms and legs. She let go of her lover and her arms naturally fell toward her sides, gradually stiffening.

She felt stretching in her skeletal structure, lengthening of vertebrae, and she assumed that she was beginning to grow taller. Before the process could get very far, though, an intangible force manifested around her, pushing down on her head, constricting around her developing gut. The vision in her mind was not a statuesque beauty like Sunset Shimmer had (briefly) become, or even a towering mountain of flesh; it was stouter, curvier. The pressure on her midsection stymied its growth, forcing that mass to instead relocate toward her chest and rear, filling out far more rapidly. Her breasts expanded out in front of her, mashing into the wall of gold, while her buttocks wobbled and her thighs ground together. Everything creaked as it stretched, swollen assets and appendages rubbing into each other, even the matted flap of her tail clapping when it swayed from one ass cheek to the other.

“What do you think?” Sunset Shimmer’s voice beamed directly into her skull, echoing.

Twilight Sparkle moaned in her thoughts, somehow.

There was a chuckle, tinged with similar exultations of pleasure. “It’s quite a lot, isn’t it? But…I feel there could be something more.”

The alicorn’s vision swam, bleeding between reality and the internal conversation, blearily groaning into Sunset Shimmer’s mouth while they kissed. She felt the touch of magic once more, but this was more purposeful, articulated, the ethereal approximation of hands. It pried open her nether lips and began to prod within, moist rubbery flesh no less sensitive despite being far smaller than the unicorn’s groin.

“What do you suppose it will be?” Sunset Shimmer asked, teasing.

Twilight Sparkle couldn’t have imagined why she bothered to ask; the image was right there in her mind to tell her—

There was nothing.

“Whatever could it be?” A taunting smirk was audible in those projected thoughts.

She was trying to panic over her confusion, desperately screaming in her mind, but there was little she could do while being mired in ecstasy. She couldn’t believe it: the internal image was being withheld from her! To what end? To keep her guessing? To keep her on edge? She was definitely on an edge, teetering closer and closer the longer the stimulation went on. The most ridiculous part was that it was actually working.

“Just one piece left to get the picture just right.” Twilight Sparkle didn’t have the attention span at the moment to observe the swelling in Sunset Shimmer’s neck all while this was transpiring; just below the base of the skull, her throat was blocked off, allowing the metaphysical filling to build up. It might have been a comical thing to observe.

“I’ll put it right here.”

Her magic squeezed the purple mare’s clit at the same time that she let the mass flow in.

Twilight Sparkle orgasmed, screaming into the unicorn’s lips, and at the same time there was one more explosive surge of growth. Her hooves were forcibly lifted from the floor, legs spread to the sides, and her heart fluttered momentarily at the thought that she was about to fall, but instead she was firmly supported, held aloft by this new addition to her anatomy. It pressed against her legs and up at the underside of her stomach. It had sprung into being just in time to catch the gush of cum from her loins, trickling over the back, framing a cleft in the surface. And it throbbed.

“Oh,” she thought in the calm of the afterglow, not needing any kind of telepathic support to come to the realization, “I have a penis now.”

“And testicles!” Sunset Shimmer added cheerily, using one of her own hands to tenderly stroke at a swollen globe. Dull waves of pleasure rose up and slammed at Twilight Sparkle from within; their sensitivity was already at a feverous high as they compressed beneath her, acting as a living sofa, holding up the entirety of her colossal bulk. Her balance would have been precarious were it not for the other mare holding onto her, keeping her steady. She was slightly front-heavy, mostly on account of the shaft which jutted out ahead, and she could already feel the anxious yearning which encompassed its entire being, its very purpose in existence, a monument to desire. It was stiff, and it was pushing against Sunset Shimmer—against what she didn’t know, but the presence of flesh around the flared tip was enough to stimulate it further, leaking yet more fluid from her vacuous depths.

“Now we’re done.” Sunset Shimmer pulled her out of her thoughts before she then began to physically pull. She was reeling back, but the seal on their lips was proving difficult to break, as if they were glued together. Twilight Sparkle would have expected she was ready to separate, but, now that the moment was upon them, she didn’t want to. She just wanted to keep kissing, that grappling tug of war between a couple’s faces. She didn’t think about the way she was stretching, the new fuchsia that was blooming into being. The force of suction only felt like it was growing stronger and stronger, the two mares fighting for who could be more ardent in their love, until abruptly the seal broke with a wet pop and they were finally freed; Twilight Sparkle once more came close to tipping over, falling backward, before strong hands steadied her.

The alicorn groaned, more from exhaustion than arousal (but only barely). Her marehood was spent, but her new stallion anatomy was howling at her, every throb like a pounding upon her skull. The frontal cannon pulsed against Sunset Shimmer’s own swollen enormity, the testicles hot and churning beneath her, filled with magma waiting to erupt. To say nothing of the sensory input which she felt from the rest of her body, so rotund and bloated and heavy, weighing upon itself, breasts on belly on butt on balls. She couldn’t keep her hands from grasping at the sides of her bosom, squeezing and kneading, pressing inward to desperately heave the colossal latex flesh. Her thighs clenched and her hooves dug into the taut sac beneath her, rubbery surface creaking. She had changed so much and the mere idea of what she had become was gnawing at her, the curiosity insatiable, she had to behold it with her own eyes.

This immediately proved difficult. Her cheeks had plumped up, forming a shelf right underneath her eyes. At the end of her muzzle, there was a canopy of shiny bright pink, flaring outward in all directions, completely occluding the view of anything directly in front of her. She reached up to fondle the swollen lobes—facing a great deal of resistance in bending her arms that far—and found that they were far too large for her palms to contain. Not that she didn’t try for a few seconds, crooning as the firm mass compressed like a stress ball. She knew what she was touching, but it was strangely far away from her face; the bridge of her muzzle was so much longer than she remembered, redoubling upon the obtrusiveness she had observed when she first came through the mirror and became a pony.

An amused chuckle accompanied a shadow casting over her, Sunset Shimmer looming overhead. “Is my new toy having a hard time ogling herself?” she mused, and her fingers traced over the mare’s cheeks, tapping at her glasses to push them back into place. “Here, this might help.”

The mental connection flashed into being once more, a television screen turning on in her skull with a fit of static, revealing an aerial view of herself. The damage was delightfully catastrophic. Her previous hyper-voluptuous physique was like a twig compared to the mountain of sleek-skinned fat and folds she had become, breasts and ass that could each fill the breadth of a sofa, fat purple nipples on puffy areoles wider than dinner plates. There was a genuine gut buried somewhere in there, as if years of idle snacking during her research had caught up to her all at once, leaving her extremities to show the extent of her obesity, swollen with flabby rolls and sleeves that inhibited her flexibility.

Twilight Sparkle wasn’t certain that she had gotten any taller—though it was difficult to say with her hooves elevated off the floor by balls which represented a near-doubling of her mass all by themselves. It seemed to her, though, that her proportions had shifted somewhat, her legs shortened, which caused her stout width to be all the more exaggerated. Conversely, all of that was offset by the cock and balls which she was perched upon, a girth which almost dwarfed the rest of her, wider than her hips, the dark amethyst shaft like the trunk of a tree, a battering ram upon any orifice so (un)fortunate as to be on its receiving end. She had difficulty identifying her own face, buried within the hills of folds that her neck had become, the familiar, albeit latexified, hair resting on top, features softened, but none altered more than her muzzle, stretched out from her face, a shape that more closely resembled horses from her home world than the ponies of Equestria, and at the end were her lips, stretched out like the petals of a flower, garish neon pink.

She was a grotesque caricature of a person, a mockery of sensibility.

And she knew that she—as well as Sunset Shimmer—was only just beginning to push her limits.

“What would you like to do next?” the unicorn asked, hungry and lascivious.

Twilight Sparkle lowed back. She could scarcely muster the ability to respond between her arousal and the discovery that her mouth didn’t move the same way anymore. The opening was sealed on the sides of her muzzle, forcing her expression into a puckered pout, lips forming an oh-so-inviting circle at the center, unable to spread or close any further. She rocked on top of her balls, the closest she could do to approximate bucking her hips, and her cock butted against golden flesh and musculature.

“I agree,” Sunset Shimmer murmured, grinning broadly, as if she had perfectly understood that nonverbal response.

She pulled her in, and the alicorn’s penis soon found the warm entrance it had craved, jammed into the cavernous slit between Sunset Shimmer’s thighs. She cradled Twilight Sparkle delicately, hauling her effortlessly in spite of her gargantuan bulk, guiding her deeper, sliding inside. The gaping vulva welcomed the shaft effortlessly, but the unicorn’s midsection visibly distorted as her womb was filled and then some, the details of the shaft bulging through the skin, burrowing through her, jostling her breasts when it pushed at their bases.

They began to rut, in an approximate sense. Sunset Shimmer did most of the work, gyrating her hips at the same time that she pumped Twilight Shimmer in and out like a living dildo, squeezing her at the hips. Sunset Shimmer’s torso distended further just from the premonitory spurts of pre, turning her chiseled abs into a wobbling balloon, yet another added to her collection of spheres. There was little that Twilight Sparkle could do on her own, lacking physical capability or the capacity to use her magic, continuing to grope her breasts. That was up until the moment that she felt something brush against her lips, which might as well have been a flint striking on coal, sparking a primal urge inside her that prompted her to clench and tighten, sucking into the glossy opening. Sunset Shimmer gasped sharply as her lower-center nipple was pulled into the other mare’s mouth, suckling fervently, yanking out and slamming back into the pliant surface, milking her dry (she couldn’t remember if she had changed her milk back to normal, and Twilight Sparkle wasn’t sufficiently concerned with tasting anything to care). When the alicorn finally let go, the nipple emerged in a completely different shape, engorged and distended, twitching at the air, the areole bulging outward. Both understood automatically to continue the process, Twilight Sparkle blindly lunging toward the next nipple while Sunset Shimmer positioned herself so that it would be easier to do so.

They continued like that, long after Twilight Sparkle had finished inflating all of Sunset Shimmer’s nipples and then ended by inflating her belly with untold gallons of semen, the two of them screaming in ecstasy. Waves of wanton desire swept from one to the other and back again, further warping their forms beyond recognition, pushing aside the furnishings in the library and flooding the floor with their fluids, animalistic cries echoing through the halls of the palace. The eldritch tome which had begun this sequence of events in the first place went forgotten, slipping away into the ether from which it had arrived, its purpose fulfilled. The two ponies were overcome with their desires, a recursive yearning that only built upon itself more and more with every iteration. Their want filled them until it was all that they were, all that defined them.

And they could be fine with that, because they each had the one person that they wanted the most.

= = = = =

Rarity grunted in a manner most unladylike, gritting her teeth and snorting.

The white pony was something of a, well, rarity among her peers, being one of the scant few inhabitants of Ponyville prone to regularly wearing full ensembles of clothing. It could be chalked up to her aspirations of living among the high-class elite of Equestria, but even the nobles of Canterlot were known to have bottomless parties on occasion. Really, Rarity was always going to be a fashion pony through and through; her motto was that there would always be more possibility to be had with a clothed body, hugging curves and defining bulges, than one that was fully nude. She designed clothes not just to show off the extent of her talent but to draw out the latent potential of a pony’s form, to make them as attractive and enticing as possible. Not everypony had the patience for that, but those who followed her model were seldomly dissatisfied with the results.

In the privacy of her own home, however, she had no compulsion to bother with those obligations; she was not so zealous as to deny the importance of simple convenience. It made it all the easier for her to slip on a dress she was working on, in the event that she needed to gauge how it was looking on a real body. It was also quite handy for granting her easy access whenever she was sufficiently worked up and in need of release. This was an occurrence that happened all too frequently when she was faced with a lack of creative drive.

The unicorn clenched and flexed as she worked at the labial folds between her legs and kneading her breasts, adding in magic to compound whatever stimulation she needed, but however much groaning and growling she produced there was more frustration than arousal in her voice. She had lost count of how many times she’d orgasmed over the course of this attempted work session, but she knew that it was taking longer and longer to work herself up to the tipping point each time. Her repetitions gradually slowed and she finally let herself slide back in her chair, reclining limply, her groin and fingers sticky. Her vision came back into focus once more, which wasn’t so desirable because it meant that she was once again looking at a blank canvas on her easel, waiting for something to come to her.

Rarity sighed heavily as she stood, her bosom and coiffed mane bobbing. “It’s just not good enough,” she muttered under her breath. “I need…something bold…I need a statement.”

Her loins throbbed dully at her, as if in response.

She roamed around her work studio, past the cupboards of supplies and the clustered dummies, to the shelves of fashion catalogs and sketch books and photo albums and—

Her brow furrowed as she caught sight of something odd. There was a thick black cover amongst the thinner and more colorful spines. She reached to pull it out, recoiling momentarily when she felt the texture of leather, a material even she rarely worked with. As she inspected the cover, she deduced that it was almost certainly a spell book, and she couldn’t remember having borrowed anything of this sort from Twilight Sparkle or anypony else. There was a twinge of familiarity at the back of her mind, a glimmer of déjà vu, but she dismissed those thoughts.

It was incredibly bizarre, but a part of her was intrigued, pondering if this was just the sort of inspiration she could use at such a desperate time.

“The malleability of flesh, hmm…” she mused before she opened the cover.

Author's Note

I ended up with a rather open-ended prompt for the viewer suggestion poll this month, so I decided to compile a little bit of elements from all of the suggestions that had been made. Also since the only real stipulation was that it was about Sunset Shimmer, I decided to have it be a continuation to An Equestrian Fling. I'm sure everyone who liked that story being relatively tame will appreciate my decision to go off the deep end. This was actually finished last week, but immediately after finishing I had to start working on The Flesh Takes. I thought I might be able to post both of them on Halloween, only to get bogged down with work yesterday and not having the time to finish editing on both.

Write a whole novel about bimbo monsters, proceed to start a whole new setup for bimbo monsters.

Head expansion was just a red herring. Lucky for you normies.

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