(FGO TF, BB to Clydesdale Stallion, Melt and Lip to Mares)

BB groaned, rolling onto her bed and kicking her legs aimlessly. She was, as usual, bored. Chaldea was boring, being nice was boring, this was boring. Senpai was out doing some Singularity or Lostbelt or whatever kept the macrotransactions going, and nobody around was any fun. Any time she tried to prank one of the usual goddesses or warriors, they acted like it was the worst thing in the world and that she had to be led to the guillotine.

“Honestly, give some pent-up queen a dick and suddenly you’re public enemy number one. It’s not fair,” muttered the woman with a pout.

She flicked some of her purple hair over her right ear, looking at the monitors in her room curiously. They all showed images of her beautiful, smiling face, since she couldn’t keep a stable connection with her Senpai at the moment. And if they were all blank, the only other things in her room were her cozy bed and a ridiculously large, soft, pink beanbag chair she’d “borrowed.”

“… I need to redecorate.”

BB called up a digital status screen, flicking through some of the random files she’d stumbled upon in Chaldea’s library, searching for ideas and DEFINITELY not changing anyone’s bookmarked ebooks to hardcore pornography. She snickered quietly to herself, only to freeze at a certain file: Trojan.HorseR.

“Seriously? A virus in our mainframe that I didn’t write?” She chuckled rolling onto her back, her keys flying across her keyboard. “Well, sorry, but this perfect kouhai doesn’t like competition. Let’s just see what you’re about, aaand…”

She opened it. Why wouldn’t she? She herself was an AI from the far future, so it’s not like any of the fossils could outcode her. Unfortunately, to her immense disappointment, the file she’d unpacked was just a static picture of a wooden horse.

“Oh. How original. I bet Odysseus is behind this.” She rolled her eyes, moving to close it. “Gonna make sure ‘he’ sends Circe an invite to-”

Her system flickered. It was a physical sensation that surpassed her data, going straight to her Saint Graph, the very essence of the closest thing to her soul.

She sat upright suddenly, her bangs hanging over her eyes. “What the hell was that?” She cast her arms wide, summoning different status screens.

One of her monitors blinked and she magnified it. VIRUS DETECTED: TROJAN.HORSEREWRITE.

“Are you freaking kidding me? I’m the virus here!” BB’s hands flew to the console. “I’m gonna find out who even tried to infect me and stick this cheap piece of malware right up their-”

Another jolt surged through her, this one stronger. She felt something strange in her code, like it was being unzipped, repackaged, and rewritten. It was new data, impossibly dense, and it was flooding her system, overwriting her.

Typos started appearing in her countercode, and she looked down to her hands accusingly, only to find them changing. Her elegant, slender fingers were thickening, knuckles cracking as they bulged and swelled beneath her skin. Her perfectly manicured fingernails were thickening, swallowing her fingers, cracking their purple polish.

“Oh that’s not g-nnngh-ah!” She doubled over, clutching her stomach. Her outfit, a white leotard, stretched. Her flat, toned belly was bulging with mass, with muscle. Her torso was thickening and stretching, ribcage barreling out with each breath she took. It had the dizzying effect of making the room seem smaller, as her shoulders were tugged higher away from her waistline.

“N-no!” She thumped a forming hoof against her keyboard, enlarging the keys through force of will. “I’ll type this freaking one key at a time if I have toooOOOH!”

A new kind of heat hit her groin, and she openly shuddered, violated. There was something new there. Something growing. This virus wasn’t just rewriting her construct as a humanoid, it was rewiring her construct as a female. A deep pressure build between her legs, followed by an aching, throbbing stretching.

Dimly, she noticed that “BoyParts.xml” was being installed into her Saint Graph.

She tried to code around it, but the weight was too distracting. It was hot, it was swelling, it was actually kind of comically ironic if she thought about it, but that only pissed her off more. Worse, it was massive. Its thick length pulled at her core, and two new tender data packages were installed below it.

“Uninstall this right NOW!” Her voice cracked, dropping an octave. She reached her hooves to her neck in shock, and in doing so missed her chance to counter-code the change to her legs.

Her bones snapped and popped as her thighs bulked up with grotesque amounts of muscle for woman, yet the perfect amount for a tough working horse. Her hips snapped and popped, throwing her to her side.

If she was the same size as before, she’d have simply fallen onto her bed. But with her torso as long as it was, she found the floor looming up towards her face frighteningly quickly. She straightened her arms to catch herself, and her shoulders popped too, both locking in a new position and tearing through her leotard.

CLOP-CLOP

“No!” She shouted, body instinctively moving, tucking her knees under herself. She half-lifted herself from her bed, slipping off them to be properly on all fours on the ground. In doing so, she felt the chill of her cool room alleviate slightly, as a short, dense coat of brown and white fur itched out to cover her.

“Stop this! I am not a hrrr… Nohhhtuhhh… Hrrrkk…” Her skull burned as it stretched, making speech impossible. Her delicate, cute features were being dragged and stretched like putty. Her sinuses burned as her nostrils widened. Her lips thickened and grew huge and rubbery. Her tongue was thick and clumsy in her new snout.

There was a noise in the hall. Footsteps. Her ears shot up, growing tall, pointed, fuzzy even. Even if it wasn’t winter, Chaldea was in an arctic base, so it looked like she’d be sporting her winter coat.

The fact that she knew what a winter coat was scared her almost as much as the realization that she naturally assumed it was hers. The virus was breaking her mind, too. Her beautiful, perfect, infinite mind was being caged in, one layer at a time.

She called up a monitor to try and display her remaining intellect, but the ability to recall numbers’ meaning was beyond her. She drooled a little for a moment, seeing the symbols change, trying to get the meaning of “5” and how it was better than “4.”

Scared. Loud noises. Room small.

She… He staggered ahead. His feet clomped on the floor. Shaggy fetlocks itched his wrists and ankles, the mark of his Clydesdale breed. He tossed some of his purple mane behind his head, ears twitching. He ached. He throbbed. He needed.

“Hrrmmph… Huff!” He snorted, feeling his pulse echo between his legs.

There was a tiny little bit of BB left in his mind. She screamed at him as he approached the soft, pink, cushy bean bag chair by her door. “You stupid horse, listen to me! I will NOT debase myself like an animal!”

The stallion stumbled forward, his ears brushing the ceiling. He lowered his massive head towards the chair. “Snnnfff…” It smelled… Not like mare. But it felt soft. He could use soft. “HRRRPHH!” He whickered.

He lowered himself onto it, feeling it press his manhood against his belly. It was soft. He humped it, and drooled like an idiot, content.

Deep in his mind, BB wailed like a cat in heat. As much as she hated this, it felt good. Too good. So good she not think… No… Wasn’t… Dummy… Was…

The stallion snorted, humping again, squishing the chair beneath him. “HHHREEIIIGH!” Thick strands of drool flew from his rubbery lips. His eyes, vacant, stupid, rolled back in his head. He stomped a hoof powerfully onto the ground.

Deep inside his mind, the other thoughts felt herself swelling, felt herself filling his form. She was… he. He was a stallion. There wasn’t any difference between his thoughts and his body. And that was great, because this felt amazing.

“Huhhh… Ghhhuuhh… NEIIGH!”

He was a staggeringly stupid, unbelievably strong, desperately horny Clydedale. He was close, so close to bursting.

Then the door opened and he reared back.

xXx Five Minutes Ago xXx

“HHHREEIIIGH!”

“Did you hear that?” Meltryllis hissed, the metallic clang of her stiletto heels halting.

“Hear what?” Passionlip asked quietly, her voice as timid as ever. She moved next to her ‘sister.’ Both of them were AI programs split off from BB, a mix of daughter and clone, which made Mother’s Day awkward for Lip. Melt simply didn’t care.

Melt rolled her eyes, lifting a knee and thumping it into Lip’s massive, pendulous breasts. BB had been a little cruel in the girl’s design, giving her cleavage that could literally swallow a man whole. “Seriously, can you not hear past these or something?

“Be nice!” Lip pouted. “All I heard was BB being… loud,” she said graciously, “as usual,” she finished honestly.

“No, not loud.” Melt strutted towards BB’s door. “That sounded like a horse.”

THUD!

Lip flinched, her comically oversized claws held out in a guard position before her. “Uh… Maybe she’s under attack? S-should we get help?”

“Huhhh… Ghhhuuhh… NEIIGH!”

“Ugh. She probably stole Bucephalos again.” Melt rolled her eyes sarcastically.

Lip raised a timid claw. “I… I think it’s pronounced Bucephalus.”

“…Lip. It’s a horse. What does it matter what he thinks?” Melt paused. “Oh shoot. What if she’s done something to Red Hare to make him fully horse? Master would hate that.”

Lip squeaked. “How does your mind even think about that?”

“I don’t know, I didn’t code me,” Melt huffed. “Let’s just go in, unscrew whatever she’s done, and-”

As Melt opened the door, the giant stallion on the other end reared up, exposing his manhood. “HRRRRUUNGH!”

Both women were superhuman. They were Servants, after all. They had the ability to move and get out of the way. But spending time in Chaldea had left them a little more human than they were previously, and their minds were totally stunned by what their eyes were telling them.

A torrent of molten hot fluid erupted from the stallion, literal gallons of active code and inactive BB drenched Meltryllis and Passionlip.

“THE HELL?”

“KYAAA!”

It plastered their hair, soaked their clothes, drenched their skin. They didn’t feel dry and didn’t think they’d be clean again.

For a second, there was only the sound of dripping, and the stallion’s deep, satisfied panting. “Hhhuuufff… Hrrrph… Huuufff…”

“Are you KIDDING ME!?” Meltryllis shrieked, her body shuddering from head to toe. She tried to wipe if off her face, her arms, she didn’t even want to think about how much got into her legs… “Get it off!”

Lip noticed the burning first. Her clawed hands rubbed uselessly at her chest and face, only smearing the stallion’s release. “W-what? Melt, this stings!”

Neither of them had the same coding skills BB had. They didn’t have a way to tell that they’d been infected by the same virus she’d been. But they could feel the effects.

Melt grunted as her legs buckled beneath her. She felt something… new. A sensation she’d never known: weight. Heaviness. The metal of her prosthetics creaked as it was rewritten into thick, heavy, jiggling flesh.

Horror dawned on her as she realized the weight was settling into one area in particular. “M-my ass!” She looked back to her trim, athletic backside, staring as it ballooned outwards. Fat and muscle packed onto it, lifting her skirt, its sheer weight pulling her backwards.

And not only was it fat, it was furry, too. An auburn fur coated her massive, wobbling backside, her regrown, powerful legs. Something in her hips popped, and she was thrown forward. She couldn’t feel her hands even before this, so seeing her new hooves clomp onto the ground before her was an unwelcome surprise.

“N-no! I’m… I’mm… MNnnHHNFF!” Her face stretched. Her tongue flopped past her stallion-stained lips, tasting its saltiness. Her eyes watered as they spread towards the sides of her head. She shook her head, her purple hair tugging behind herself into a mane. Purple… Mane.

She looked back to the raggedly panting stallion, realizing who’d just defiled her. “NNNFFff… Hrr… NEIGH!” She tried to curse him out, but that was as close as she could manage.

Beside her, Passionlip was collapsing chest-first.

Lip’s comically, already inhuman breasts didn’t shrink. Instead, they thickened, darkening, two islands of tit surrounded by cream-colored fur. They dragged on the floor between her clawed hands, and she kicked her changing legs out against the wall.

But that wasn’t the worst of it.

Between her legs, something was distending. Swelling. Bulging. Her skin stretched, dark, leathery like her tits. Two… more teats grew from them, pressing against the floor as her own udder grew to be the same size as the tits hanging from her chest.

Both sloshed at either end, heavy, hanging. She was a monstrous caricature of a fertile horse.

“KYYAAHLLK… HRRRNNIEIIGH!” She whined, her throat bulging, face stretching. Her lashes grew long, fluttering. She stomped her clawed hands against the ground, but they clopped, reforming into thick hooves of her own.

Lip tried to call out to Melt, but the best she could manage was a strangely feminine “Neeiigh…”

Melt snorted in response, keenly aware of her long jaw’s inability to form words. Worse, she also felt something in her brain fogging.

The stallion snorted, clearly interested. Both of them froze, turning towards him in horror. They tried to run, they really did.

Meltryllis, her body unbalanced by her colossal new ass, could only make it a fumbled step at a time. Passionlip, weighed down by her breasts and udder, couldn’t even get her legs under her. The former bumped into the latter, their bodies tangling in a mess of mare.

The stallion snorted over them, suddenly close. Too close.

Their hearts thumped faster. This… This was new. This wasn’t bad. A new instinct skipped straight past their brains, exploding into their wombs. It was a primal, female need.

They didn’t even notice that they’d grown tails, yet both of them flicked their tails to the side nonetheless, fanning their scent, their heat towards the stallion. They needed foals. They needed a stud.

What was left of their human minds dripped down between their legs, matting the fur of their thighs. They didn’t care. They needed this.

Unfortunately for everyone else in Chaldea, this need happened to be in the middle of the hall, and soon others would be joining their herd…