“Hey! It’s getting late, you almost done for the day?”

“Almost. I’m still working on that personal project.” Dr. January Takamura shoved the voice call window into the bottom right corner of her centre monitor while she used the other three to work.

“Don’t get in trouble. You know how the higher ups get about doing personal work on the clock.”

“I know, but I’m almost done.” Jan typed furiously across three screens, filling in data fields and inputting ratios and volumes of chemicals. “Just got to do field testing and it’s ready to go. Ah, speaking of which, I don’t want to spoil the surprise so I’m going to have to say goodbye for now. How soon can you get to the lab?”

“About fifteen minutes, give or take.”

“That should be plenty of time, then.”

“Love you, Jan.”

“I love you, too, Mike.” Jan ended the call and turned her full attention back to her computer. All that was left was to actually produce the serum and then test it. Which would be done on herself, of course. What self-respecting mad scientist would even consider testing their latest invention on someone else when they could jump in headfirst? And Jan would be the first to admit that she was as mad as they came. She was good at coming across like a normal biochemical engineer to the various high ranking government officials that provided her lab with funding, but she had the soul of a mad scientist. No sane scientist could do the things she did, that was for sure.

Which meant she had a lot of leeway, and in turn was probably how she managed to get away with all the work on this one personal project. They couldn’t fire her because no one else could do what she did. What was initially intended as an anniversary present had turned into half a decade of hard work. Her metaphorical blood, sweat, and tears were finally about to bear fruit.

Coincidentally and conveniently, they were about to bear fruit on their anniversary. Just, you know, five years late. But that was fine. Better late than never.

She and Mike had been together for a very long time, at least fifteen years at this point. And their relationship was good. Great, even. He helped keep her grounded, which was something every mad scientist needed. The problem, if you could even really call it that, was that he had certain... specific tastes when it came to women. The kind of specific tastes that a real human being couldn’t possibly meet. He said that it wasn’t a problem, and she believed him.

But, well, Jan was something of a perfectionist. She wasn’t just a human, she was a genius. Mike may be content to keep his fantasies just that, but she wasn’t. Not when it would be so trivial to just make a serum that could make her the girl of his dreams.

Besides, strap-ons were fun but she’d always been curious about how the real thing felt.

One click and the machine produced a small vial of thick, off-white liquid. Exactly to plan, so far. There was no need for hesitation – Jan was confident that it would work just fine. Besides, she only had fifteen minutes until Mike got to the lab, and the serum took time to kick in. She downed it in one go before carefully placing the empty vial into a disposal receptacle. It would be impossible to clean it thoroughly enough to avoid leaving a residue of serum, after all. And even just plain water could react with the formula in unexpected ways, and once that happened even Jan couldn’t say for certain what it might do. Reusing used vials for anything else was out of the question. Too dangerous, too unpredictable. It was safer to just destroy it and buy new ones. Once that was done, she turned her attention to herself. The main event, as it were.

Jan was, relative to her age and genetic history and sex, fairly tall. Willowy was the term that was generally used. She felt that she was closer to lanky, personally, but to each their own. Mike found her attractive enough, though she was absolutely certain he’d find her more attractive once the changes finished. She could already feel them kicking in. A warmth, starting in her stomach and quickly spreading to the rest of her body before intensifying. Warmth became heat, like the air conditioning went out on a sweltering mid-July day but inside of her body.

She had, of course, made sure to include measures to mitigate the inherent pain of transformation. The shifting and lengthening of bones hurt, like breaking every single one of them over and over and over in quick succession. Growing pains times a billion. So, she had the serum make the body temporarily ramp up the production of two specific hormones. The first acted as a numbing agent, dulling all physical sensation. Can’t feel pain if you can’t feel anything – although, of course, that was a bit of an overstatement. Sensation was dulled, not negated. She could have completely negated all physical sensation if she wanted to, but that was always risky. People felt pain for a reason, and she didn’t want to run the risk of not noticing something had gone wrong. Which is where that second hormone came into play.

Jan’s hands had already moved on their own, before she even noticed. One had firmly grasped one of her pert breasts, the other slipped under her waistband and into her panties. “Oh fuck, that’s better than I expected.” Dull the pain, and overwhelm what was left with pleasure. She stumbled backwards until she hit a wall, and allowed her body to slump back and down until she was sitting. Safer than standing – between the numbness and the overstimulation, there was a very real chance she might fall and injure herself. Hell, with the way her hips were bucking she’d definitely have already fallen and injured herself by now.

Her breathing came slow and heavy, and that heat intensified again. Her whole body was practically soaked with sweat, by this point, seeping into her clothes and hair and fur. Because she definitely had fur now. Her clothes strained against her larger frame, and strained more as her frame got larger. Her very bones creaked and groaned as they lengthened and thickened. And, speaking of bones, she found herself having to remove the hand that was squeezing her growing tits because her new bone was already above average, and was very quickly surpassing the point where one hand was enough.

Idly, she wondered if maybe that was overdoing it. Just a bit. But only idly. Mike was kind of an insufferable size queen when it came to taking dick, and her projected final size was around the same as their biggest dildos. Also it was obviously too late to have second thoughts now. If it really did turn out to be too much it wasn’t like she couldn’t just use some more mad science to shrink it down a bit. Or maybe make Mike a bit bigger. He’d probably balk at that, of course. In addition to being an insufferable size queen, he was also an incurable bottom. He liked being shorter than his partner. But, well, this was all a lot easier to undo than you would expect. And Jan wasn’t exactly gonna say no to making his cock bigger, especially once she finished growing. In fact, she couldn’t stop fuckin’ thinking about it.

Jan quickly, albeit reluctantly, yanked her hands away from her shaft. She could feel a climax building and so she had to stop. Not that cumming would be a problem – of course she didn’t have a refractory period, what kind of mad scientist would turn themselves into a hyper amazon horse herm and make it so they could only cum once every few hours? Jan could cum once every few seconds and keep going for hours. It was just that, well, she wanted her first male climax to be inside Mike. Call her sentimental. You’d probably be right! But fuck you there wasn’t anything wrong with being a bit sentimental. And anyway, it was a good distraction from the pleasure. She didn’t want to cum yet, but her body had other plans.

Thankfully, she only had to hold out for about a minute. She’d engineered the transformation to be quick for this specific purpose. The numbness faded and the pleasure... well, it was still there, just as intense as it had been – if not moreso. But it wasn’t quite so overwhelming as it had been. More like an incessant background radiation of Horny than being constantly on the verge of cumming every second. “I still have about thirteen minutes left until Mike gets here,” she said to herself. “Just about enough time to double check the results.” She was fairly confident, of course, that everything had gone as planned. It felt like everything had gone as planned, and as a mad scientist her instinctive ethos was to cut once and measure at some point maybe if she felt like it. But, well, there was always variance, and she was curious about the exact measurements.

First off, the stuff she could eyeball. Stuff that couldn’t really be measured (or could but it would be pointless), and also just things that were obvious to the naked eye. Like, for instance, the fact that her line of sight was a good foot and a half taller than it had been two and a half minutes ago. Couldn’t not notice that if she tried. That was enough for her to be fairly sure that she’d hit the target height just about exactly. Too much under and she likely wouldn’t have noticed the difference. Too much over and she’d be bumping her head on the ceiling. She was, of course, still going to measure herself to be sure. For all she knew she’d somehow managed to make her lab shrink. Absurd, but this was mad science so very little was outside the realm of plausibility.

Speaking of things she could see with her eyes, the actual transformation. She was a horse, though obviously not entirely a horse because that would be a really stupid thing to do to herself and extremely difficult to reverse. She’d given herself all the best bits of a horse while still remaining bipedal and retaining her opposable thumbs and such. She’d elected on dark chocolatey-brown fur with a black mane and tail, the same colour as her hair before she transformed. In terms of the head she’d elected to go equine, but not fully equine. A bit cartoony, with the features softened so she didn’t look like she was wearing that one ridiculous looking horse head mask. Having more front-facing eyes also helped to soften that effect.

Oh, and of course she had a horse penis. Can’t forget that, considering it was a big part of the fucking point of the whole exercise. Mike was into big girls with horse heads and giant horse penises, so Jan made herself a big girl with a horse head and a giant horse penis. Airtight logic. Everything was specifically tailored to his tastes. And, of course, everything else was bigger too. Gone was her old mad scientist build. In its place, something more akin to a porn star but wildly exaggerated. The kind of proportions you could only see in a drawing, same as with the horse features.

Her clothes, she noticed, had survived the transformation. Barely. She had not grown enough to outgrow them, which was annoying because everything was tight and uncomfortable. Her head-sized tits were squashed by her shirt, spilling out through every available orifice. Thankfully, she’d gotten her cock out of her pants or else she imagined there’d be a similar situation down there – though that was made up for by balls the size of her fists. Big and full and absurdly productive, just how her lover liked ‘em but in pants decidedly not designed for them. And of course her tail was also causing some issues in her rear, making them uncomfortable on both ends. Fuck, even her lab coat was squeezing against her back and shoulders and compressing her arms. It was kind of hard for her to even move, and she obviously didn’t want to experience what it’s like to get your balls crushed.

Luckily, she’d planned around her clothing no longer fitting anyway.  She wasn’t particularly attached to this outfit and she’d gotten a replacement labcoat that was significantly bigger and more robust. And this was a good chance to test one of the less immediately obvious features of the transformation. Mike was into strong women but not particularly into overly buff women, and so Jan had come up with a compromise. By default, she was decently athletic. With a flex of her arms, the muscles came out and shredded the top half of her clothing. They weren’t actually all that extreme in comparison to a real life bodybuilder, but they were enough bigger than her default to be the straw that broke the labcoat’s back. And the definition was amazing. Again, she had proportions that were almost impossible outside of cartoons. She bent her legs slightly and that was enough for the bottom half of her clothes to follow suit. Sadly, given the lab’s severe lack of a proper mirror, getting a good look at her new rear wasn’t in the cards. She had to rely on the floor, which was admittedly not a bad substitute. Clean and sanitized enough that, she could at least see the shape of the thing. And she very much liked what she saw. Like her breasts, each cheek was around the size of her head, round and firm. Firmer than her breasts, a fact that she confirmed by reaching down and giving one a squeeze. Not so hard she couldn’t sink her fingers in there a bit, but a good portion of it was clearly muscle. The cheeks pressed together nicely, with her tail dangling in between. Her figure was perfectly balanced, exactly the way Mike liked it.

She elected to not put on her new lab coat just yet. Weighing herself was best done while she was nude, so that her clothing didn’t throw things off. She had engineered a special one-stop measurement device specifically for this part, so that she didn’t need to have five different things taking up space in her lab. Instead, she just stepped onto a platform and stood up as straight as she could. “Height.” A display lit up, signifying that she was two hundred and twenty eight centimetres tall. Seven foot six, exactly what she’d calculated. So far, everything was going to plan. Almost too much to plan, actually. As a mad scientist, she was used to there being fairly significant variance when it came to her experiments. Consistency wasn’t her strong suit, and so the fact that this was thus far turning out exactly according to plan ironically had her worried. Something was going to not match her calculations, and the longer it took her to find that something, the more likely it was to be something significant.

“Weight,” she said tersely. Once again, the display lit up with numbers. “T-two hundred and twenty one kilograms!?” There’s the other shoe. She had planned around being proportionally heavier than she was when she was a lanky nerdy human, but this put her at almost five hundred pounds, about one hundred and thirty pounds above where she should have been. Where the fuck was all that extra weight coming from?

Of course, even as the thought crossed her mind, she had an idea of what the cause was. Fuck, it was so blindingly obvious that she was shocked she hadn’t planned around it in the first dang place. “Lifting power test.” She grabbed a pair of bars on either side of the display and pulled them upwards as hard as she could.

“There we go. Four hundred and forty two kilograms. That’s almost half a ton of lifting power. No wonder there’s so much extra weight, my muscles must be absurdly dense.” A lot of it was also probably the result of her tits, and especially her balls – which were intentionally extra dense, so that they could produce ten times as much semen a hundred times faster than testicles of the same volume but lower mass. She wasn’t going to measure their exact mass, of course, because that was more complicated than her measurement platform could manage. It could measure her output, but again; she wanted to save her first male orgasm for Mike.

That’s not to say she wouldn’t be doing any dick measuring though. “Length.” One last time, the display lit up, confirming that her cock was seventy six point two centimetres long. Two and a half feet was just about as much as she was comfortably willing to stuff into her boyfriend’s femboy butt, lest she run the risk of breaking him. Or at least until she convinced him to let her augment his durability and stretchiness, but that could wait. Between removing her clothing and measuring her new body, about ten further minutes had passed. Mike would be here in just three minutes, which left her just about enough time to put on the finishing touches. She grabbed her new, bigger lab coat and put it on before turning her attention to her mane. Seven foot tall horse herm she might have been, but she was still a lady dammit. She wanted to make sure she looked as good as possible before absolutely wrecking it by fucking her partner senseless.

Speaking of which, it had been exactly fifteen minutes since the call ended. Jan made her way over to the door and, approximately thirty five seconds later, there was a knock. “You’re late.”

“I am not late!”

“You are exactly thirty five seconds late.”

“Oh, well, excuse me for not being perfectly accurate down to the millisecond about when I’d get here.”

“Precision is important.”

“Can you please let me in so we don’t have to have this conversation through a closed door?”

“Of course. I need to show you your surprise anyway.”

“Since when is your personal project my surprise.”

“Since the beginning, dear,” Jan replied, pressing a button that made the door slowly slide open. “I didn’t tell you it was for you because that would have spoiled the surprise, of course.”

“Of course. So wha-”

Whatever he was going to say died in his throat as the door opened enough for him to see his girlfriend’s two and a half foot horsecock. Slowly, his eyes traced up her body, lingering on her midriff (which was at eye-level) and her breasts (which were not), before finally settling on her face.

“Happy anniversary! Ass or face.”

Mike stared in stunned silence for about a minute further. “Well, I mean. Both in due time?”

“If it helps, there’s no security cameras in the hallway and the custodial staff shouldn’t be anywhere near here for another hour.”

“Oh well in that case let me just get my pants off and we can skip to the good bit.”

“Here, let me.” Jan reached down, grabbing the hem of Mike’s pants with one hand in the front and the other in the back. She effortlessly tore them in half, idly discarding them before quickly doing the same to his underwear.

“Oh okay.”

“Sorry, I wanted my first orgasm to be in you, so I’ve been holding off and I’m a little eager as a result.”

“I hadn’t noticed,” Mike replied, taking the opportunity to pull off his shirt. “Can I get my shoes and socks off, too?”

“Turn around and bend over.”

“I’ll take that as a no.”

Mike had never been the most masculine of men. Jan had no problems with that, of course. Jan had pretty broad tastes when it came to men and women and just about anything in between, and she was very willing to try and experiment. But, well, that didn’t mean she didn’t have her own tastes. To put things bluntly, she liked femboys. Short, skinny, feminine, ideally with a fat ass – all things that Mike had in spades. Jan honestly couldn’t say which came first, her specific tastes in men or dating Mike. Either was possible, and they’d been together for so long that she couldn’t remember for certain.

The point was, though, that he had a very nice ass when you considered she hadn’t done any mad science to it yet. He bent over and gave her a very good look at it. Nice and round and soft. Big, at least by traditional standards. She could fine tune it later, now that she’d properly field tested the procedure, but it was a pretty damn good baseline considering that it was entirely natural. Butt-cleavage deep enough that she had to actively pull the cheeks apart to get at the hole. She gently prodded at it and then stopped, briefly, to marvel at the sensation. She had plenty of experience doing Mike in the ass, but obviously that was with a strap-on. This would be the first time her penis had touched something aside from her. Hell, she herself had barely come into contact with it at this point. She pressed the flared head against Mike’s body again, revelling in the sensation. It was a lot, way more intense than regular sex.

“Mnnnn, I think I made it a bit too sensitive,” she muttered as it throbbed, letting out thick gouts of translucent precum.

“At least we’re not gonna have to worry about lube?”

“I’m gonna put it in, okay?”

“Gotcha.” Mike visibly braced himself, tensing up his arms and shoulders while relaxing his lower body. They both had plenty of experience with pegging, and Mike was a bit of a size-queen. He liked really big cocks and knew what to do to take ‘em. Likewise, Jan had extensive experience, so she knew exactly what to do. A little bit more rubbing and a touch of hot-dogging to get herself nice and lubed up. Then press, release, press, release, presssss and release, each time pushing a bit harder. You couldn’t outright force your way in, lest you run the risk of causing an unpleasant injury, and that was doubly important with a two and a half feet long horsecock. Not only was it long, it was also girthy. Mike could take it, she knew Mike could take it. But no one stood a chance against two and a half feet dry. So, as much as she really wanted to go full-force right away, she took her time and let things build up slowly.

Even if it was very hard not to just cum right then and there. She had held back this long for the sake of cumming inside Mike so god dammit she was going to cum inside Mike. Even if it meant maybe not taking the time necessary to savour the experience. She had plenty of time to savour the experience of fucking her boyfriend’s ass with a two and a half foot horsecock so she could afford to maybe rush this particular one, just a bit. Find just the right balance between fast and slow that prevented her from firing her shot too early while also not injuring Mike.

“Mnnn, I thought you said you were gonna put it in.”

Of course, on the other hand, Mike was enough of an insatiable cockslut that he clearly wanted her to do that whole shoving it in dry thing. And she was pretty thoroughly lubed at this point, thanks to the copious precum. She was pretty sure that, at this point, there was minimal chance of injury – and, in the worst case scenario, she could probably use mad science to quickly rectify things. So fuck it, it was time to dive in. “I did, didn’t I?” She pulled her hips back, carefully angled her shaft, and then slammed forward as deep as she could go.

God, he was so fucking tight. Jan wasn’t sure how much of that was him and how much was the sheer raw size of her member. Somehow, actually having it inside of someone else made it feel bigger than it frankly already was. The fact that she could only manage to get it in up to the medial ring likely helped that perception. “F-fuck,” she groaned as it throbbed and pulsed inside of him. “Were you always this warm?”

“Were you always this big?!”

“No. Obviously.” Jan took a brief moment to revel in the sensation of just being inside of Mike. The way her cock’s throbbing pressed against his insides, and the way they in turn undulated in a futile attempt to get her back out. Only a moment, though, because that was about as long as she could hold back. Maybe she could have lasted longer if she’d let off some steam earlier. As it was, she’d been holding back for fifteen minutes already. There was a tightness in her chest and at the base of her shaft. “Ah. I- ahhhhhnnn~” Her balls pulled tightly against her body. “I’m gonna-” Her muscles locked up, quivering with anticipation. “I’m gonnaaaaahhhnnnnn~” Her hips bucked, and her cock swelled, starting at the base and sloooowly travelling its way up the two and a half feet of meat. “I’m gonna cummmmmmm!”

That was slightly disingenuous. She wasn’t gonna cum, she was cumming. And cumming and cumming and cumming and so on. There was a lot, was the point. Likely, assuming things had gone to formula, enough to be measured in gallons. She couldn’t get more exact than that, yet. She was going to have to go back into the lab and properly test her output after this was done, though she found herself regretting her sentimental decision not to do that first. Not because she didn’t have the exact measurements of her cumshot, but because she would have known in advance just how much it was. Clearly, she’d let her own libido get away from her when it came to her productivity. Just a bit. It was part of the fantasy, yes, but this was beyond what a human being could physically take. Like a firehose sticking out of her crotch and into her significant other.

Thankfully, the sheer force of her climax was enough to force his body off almost immediately. Any longer and he might have suffered permanent damage, which obviously was something she’d prefer to avoid. On the other hand, though, she found herself suddenly making a much bigger mess than she had intended. “Note to self,” she muttered, barely managing to form a coherent sentence. “Make sure to treat the custodial staff assigned to this hallway to a drink. Or ten.”

She collapsed backwards, hips bucking as she continued to cum. And cum and cum and, again, so on. Gout after gout, painting the walls with thick streaks of viscous white goop. In the end, it only lasted a few minutes. Which didn’t sound like a lot, particularly, until you took into account that the average human orgasm only lasts a few seconds at most. This was overwhelming. She was absolutely going to have to do some serious adjustments in this regard. Perhaps tone down the sensitivity and increase stamina? But she’d already increased her stamina, and she didn’t really want to tone down her sensitivity. Maybe find some way to boost her psychological resilience?

Whatever, she could deal with that later. Right now she needed to recover and then get to measuring her output.

“Are you done?”

“I think so.”

“Okay.” Mike slowly pulled himself up, and made a futile attempt to wipe some of the cum off of his body. He’d been front and centre and so had taken a good part of the brunt, at least at first. Enough that he would need a lot more than some casual wiping to clean himself off. “Do you happen to have a shower in your office or something?”

“No, but I do have an emergency shower.”

“That’s a type of shower.”

“It’s not fun but it should be enough to get you clean so long as you don’t mind a few gallons of water getting dumped on your head in one go.”

“Oh.” Mike made a face. “I’ll just use the sink, if that’s okay.”

“We’ll figure something out. I’d also like to do some more measurements.” And, though she didn’t say so out loud, she didn’t want to risk getting caught by the custodial staff. Even if she felt a bit bad about leaving this mess for them to clean, she didn’t want to have to explain to the people who had to clean up several gallons of cum exactly why they had to do that. Luckily, she had an hour before the scheduled time to clean the hallway. Plenty of time to measure her output and then figure out a way to clean up after herself – with some extra time to bask in the afterglow, to boot. “Come on, let’s get you cleaned up.”

“Yes, ma’am!” Mike gave a mock salute and walked into her lab. Jan sighed, before pulling herself upright and following him in and shutting the door.

And, two minutes later, Hans the janitor arrived ahead of schedule. “Ah, heck,” he muttered as he looked at the cataclysmic mess ahead of him. “Shoulda known that it was too good t’be true.”

Janitorial work in a lab setting was no joke. This wasn’t like a school or an office. You never knew what chemicals might end up reacting poorly with your cleaning supplies. Even just water could potentially lead to a fire or explosion. Every individual lab space had different work being done in it, too, and thus required a different approach. The one commonality was that you had to be extremely careful and delicate. Which meant that, normally cleaning took a very long time. There was simply no way to do a good job quickly without it being incredibly unsafe.

Today had started out like it was going to be one of the rare easy days. Most of the scientists had taken the day off – and so he had completely left the unoccupied labs alone, lest it turn out they were working on something that turned into poisonous gas when exposed to Mr. Clean. Turns out that had been a bad omen. Everyone was away because Dr. Takamura was up to something weird again. Hans was very used to cleaning up Mystery Fluids during his day-to-day work routine, but this was no mystery fluid. Any man would know exactly what this was, just by looking at it or smelling it.

And there was a fuckin’ lot of it, too. “Jesus, she had to have gotten like twenty guys to make this much,” he muttered. “And at work, too. Isn’t she married?” Whatever. Work was work, and a mess was a mess. They didn’t pay him to ask questions, they paid him to clean shit up. Thankfully, this wasn’t the kind of mess that required any kind of special technique or equipment. It was gross but it wasn’t any strange, unidentified chemicals. Just the aftermath of an inexplicable hallway orgy. If it weren’t for the sheer volume of the stuff he’d probably be able to get it cleaned up lickety-split. As it was, his easy day had just gotten a whole lot worse.

Step one was to call up the other janitorial staff and let them know he was going to be running late after all. “I’m also going to need rags. Lots and lots and lots of rags.”

“How many is a lot?”

“How many do we have?”

“... What exactly are you trying to clean up? Did someone die?”

Hans elected to not go into gritty detail. The person on the other end of the line was relatively young, new, and – most pointedly – a girl. One of a set of triplets that had started work at the labs over the summer. Good kids, but probably not quite deep enough in the Janitor Lifestyle that they could clean up a random public orgy without picking up a few mental scars. “Someone made a very big mess.”

“Sounds like it, geeze. You gonna need anything special?”

“We’re going to need to sanitize things, but we can just use the regular stuff in this case.”

“Gotcha, I’ll get all that ready for you. Good luck, don’t die.”

“I’m not in any danger of dying.” Now that that was settled, it was time for a preliminary cleanup. He was, of course, not going to be making a dent in the mess without a lot more supplies. But he could, at least, physically stuff the worst of it into trash bags or something. He slipped some gloves on, because technically this was organic matter which meant technically it was a biohazard. Not quite enough to warrant going full-on hazmat, so some of it would probably end up slipping through the gaps, but he wasn’t going to intentionally touch the stuff with his bare god damn hands. Gloves were a good compromise, even if it wasn’t perfect. After this was done he was going to have a nice, long, thorough shower.

He was also going to have to dispose of it in a specific, particular way – again, technically a biohazard. Non-contagious organic matter goes in the non-contagious organic matter hole. Although, now he thought of it, he didn’t actually know that this organic matter was non-contagious. Ugh, he was going to have to ask Dr. Takamura about that, wasn’t he?

For now, that could wait until the mess was cleaned up. Which was going to take a while, because there was a lot of it. Even just roughly shovelling it into watertight bags was time consuming, and it got all over him in the process. “Maybe I shoulda gone full-on hazmat,” he muttered. Some of it had definitely worked its way in between his gloves and sleeves, because he was acutely aware of the sensation of it against his skin. It sort of tingled, which under normal circumstances would be worrying but in this case it was definitely just the result of knowing exactly what it was. He took solace in the knowledge that, at the very least, it wasn’t the grossest thing he’d had to get elbow-deep in over the course of his many years of custodial work.

Eventually, he ran out of watertight bags. There was still a decent amount of the stuff left, too, which was annoying. “Okay. Logistics. I need to get more bags, so let’s start carrying the ones I’ve got off to the disposal site and then get more on the way back.” From there, he could just leave them in the organic material disposal facility until he’d asked Dr. Takamura whether they were contagious or not. Hopefully no one would be stupid enough to touch the stuff in the meantime.

Normally, Hans would have trouble carrying more than two filled trash bags at once, depending on what they were full of. He liked to get as much shit as he could in ‘em to minimize waste, and so they tended to be heavy. And liquid waste tended to be heavier than solid waste, so he was probably only going to be able to carry one at a time, both hands required.

Then he actually picked one up and it felt like nothing. “... Huh. Guess this stuff’s lighter than I expected?” That didn’t really make sense, but Hans decided to pretend it did because he didn’t want to think about the alternative right now. He’d already spent frankly too much time cleaning up a massive pile of semen, he really didn’t want to think about the possible effects of whatever mad science had been done to it. Fuck, suddenly he was a lot more aware of the tingling in his forearms even if he forced it to the back of his mind. He grabbed several more bags, until he reached the point where he couldn’t physically fit any more in his hands, and hauled them off to the organic matter disposal site.

And all the while he tried really hard not to think about the fact that the bags somehow felt lighter with every step he took. Which was hard to do now that he’d noticed it. About halfway to the disposal site he paused, taking a moment to stand still and take stock of the situation. Obviously this was the result of something fucky going on with the bags of stuff. What exactly that was, he didn’t know, but it was something and it was fucky and obviously he should have asked Dr. Takamura what was up the second he felt the tingling. That was on him. The way he saw it, he had two options. Either steel his will and bring the bags he had to the disposal site and then head back to talk to Dr. Takamura before disposing of the rest, like he had initially planned. Or he could drop what he had here and go back now. The former would take longer but the latter involved leaving the bags unattended in a place where he couldn’t guarantee no one would fiddle with them. Neither solution was ideal, to be honest, but it was that or just sort of stand around doing nothing like an idiot – and he felt like enough of an idiot right now, thank you very much. So, rather than stand around, he was going to make a snap judgment and go with it.

Or at least that was the plan, but before he could make that snap judgment his body decided to make the decision for him. His hands convulsed as every single muscle in is body flexed at once, without any conscious input from him. In the process he dropped the bags, and they popped upon impact with the ground, spreading their contents all over the place. God dammit, he was going to have to clean that shit up again. Which would have really gotten under his skin if he didn’t have other, more pressing concerns. Like, obviously, the fact that he’d just had a massive full-body muscle spasm.

Make that two full-body muscle spasms. Hans quickly braced himself against the nearest wall, just barely in time that the third didn’t take him off his feet. He didn’t have the time to compose himself before he got hit by the next one, and then again. He briefly kicked himself for taking too long to decide on turning around, but only briefly, because he got hit by another spasm. Frankly, he was baffled that he hadn’t fallen over yet. The tingling had gotten worse, too. It had spread to his legs – probably the result of those burst bags getting all over the place, including into his boots – while his arms had gotten a lot worse. It wasn’t quite a burning sensation, but he sure did feel like he was on fire. Sweltering, like there was a sauna inside of his jumpsuit, concentrated inside of the arms. It was almost unbearably hot, as though he was wearing full-on dead of winter layers in the Sahara and only getting hotter. The only reason he didn’t tear off his shirt was because he’d frankly already gotten enough stuff on him as it was. Besides, even if it wasn’t a proper hazmat outfit, it was still extremely robust. There was no way he was strong enough to just tear it off-

Shrrrrrippp!

Or so he thought. The sleeves in his clothing went first, and then his jumpsuit followed soon after, bursting open at the seams and unleashing his arms. Hans had never exactly been a beefy guy. He wasn’t weak, either – you had to have some amount of upper body strength to get by in custodial work for as long as he had. But, well, he was a janitor in his mid-forties and he was built like one. Dumpy, kinda fat, starting to show his age all over his face which he hid underneath facial hair.

Though normally he wasn’t quite as hairy as his arms apparently were now. Completely coated in short, black, shiny... fur? Fur. “Well, okay, I guess that answers that,” he muttered as he stared in awe. The first thing he noticed was the fur, but only barely after that was their sheer fucking size. It wasn’t just the muscles – although holy shit were they jacked – but also the length. They looked like they’d reach midway down his calves if he weren’t still using them to brace himself against the wall. Disproportionately huge, with huge being the operative word. The size and definition of his muscles would make bodybuilders look like children. And, with every throb, every pulse, every spasm, they got ever so slightly bigger. And he could feel it spreading. That tingling in his legs had gotten a whole lot tinglier, and he could feel the sweltering heat building there as well as spreading across his shoulders and to his chest and neck and down his back. He was already fairly broad shouldered, but that didn’t stop his shoulders from sloooooooowly broadening, and the muscles on his back swelled and throbbed in anticipation of the coming growth spurt.

Slowly, a grin spread across his face. “Well,” he mused in between laboured breaths as he pulled himself away from the wall so he could flex his arms a bit and revel in biceps the size of watermelons. “I guess it could have been a lot wooooooh shit.” Okay so maybe he still needed to use the wall as a support for now. That was fine, he was actually pretty down with this now that he knew the broad strokes of what was happening. He wasn’t entirely down with being an animal person on its own, even if it felt really good. But the muscles made it worth it.

So he had a bit of a vain streak, sue him. He was pretty sure most guys would be into getting a body like a marble statue without having to do a lick of work for it. Even if it did mean turning into some sorta furry in the process. He could deal with that. That grin resurfaced, bigger than before, as the heat returned, this time centred in his chest. There was a familiar tightness, and a series of increasingly intense spasms, just like had happened right before his sleeves burst. “Mnnn, hell yeah, gimme some fuckin’ pecs,” he muttered as the spasms built to a crescendo and the stitches holding his jumpsuit’s sides and shoulders popped one by one by one until-

“... Huh. Those aren’t pecs.”

Honestly, he felt like he should probably have been more put off by the head-sized tits he’d just sprouted. As it was, he was just kind of bemused, which was probably a red flag now that he thought of it. Still, they were pretty fuckin’ big. They were easily the size of his head, but round and firm – without being so round and firm that they looked fake. All in all, they were top-tier titties. Aside from the fact that they were on him, which he wasn’t quite sold on yet. He didn’t get much time to dwell on that, though, because the tingling and heat was spreading again, faster this time. His shoulders broadened again, and this time his back muscles didn’t just tremble in anticipation. He wanted to reach back and feel them as they grew, but the last time he’d tried taking his hands off the wall he had nearly fallen on his face. The tingling made its way up his neck and down his torso, settling in his fat gut that very quickly melted away into rock hard abs. They undulated and throbbed as they swelled with power, and his whole torso started to lengthen to match the scale of his arms. That did a very good job of selling him on the whole thing.

“Mnnnn, yessssss,” he groaned as his neck was enveloped in fur and his voice went up a few octaves. That wasn’t really surprising, considering the boobs. He still wasn’t sure what to feel about it, though once again he didn’t get to dwell on that subject for long before the transformation interrupted him. This time it was his feet and calves. He very briefly worried that he might end up getting injured – he was wearing fairly heavy duty work boots, after all. He’d paid quite a lot for them, and he wasn’t sure whether to be relieved or irritated when they burst open like nothing. At the same time, his body slid up the wall as his calves lengthened and thickened with even more raw power. The stuff with the boobs and the voice aside, she was increasingly feeling that the muscle more than made up for-

Heather frowned. She? Heather? That was new. It was just enough to break through the fog of arousal the change had resulted in, if only for a moment. She pulled away from the wall and carefully shuffled her way over to the nearest lab door, which doubled as the nearest reflective surface. Sure enough, her head had changed. “So, I’m a horse now, I guess?” she said, reaching up and touching her face. “Definitely a girl horse, too. I didn’t know that a horse could be so obviously a girl.” And, if she was brutally honest, not an unattractive girl, either. Her features were just a bit softer than a real horse’s, with some elements of a human face worked in. Enough to make it hit the right buttons for someone who didn’t normally find herself wanting to fuck a horse but not so many that she wasn’t still very obviously a horse. Some furry shit, in other words. Still, she had pretty eyes and very nice hair. A very nice mane? Was that what you called horse hair? And, even as a horse, she was visibly a lot younger, which was a huge plus. “I think I can work with this,” she muttered to herself. Maybe that was just a result of the obvious mental changes that came along with the change to her head, though – like the fact that she had smoothly transitioned to thinking of herself as a she.

Once again, she didn’t get the chance to properly wrap her head around all the changes before the heat intensified again. There were only so many parts of her left to change, though, so hopefully she’d be able to sit back and take this all in after that was done. Even if she found herself not caring quite as much as she had. Or at all. Though, now that she thought about it, she should probably at least get out of the hallway. Just in case someone walked by right as Little Heather inevitably came out to play. Now that she thought of it, she didn’t really mind the prospect that much,  but the hallway was starting to get a little cramped anyway. The labs would have a bit more breathing room, for now.

Normally, you had to input a specific code on a keypad beside the door. Heather, as head custodian, had access to a master code that opened every door. Both of those options took too fucking long for her tastes right now. So, instead, she reached down, shoved her fingers under the door, and pulled it up. Or at least that was the goal. What actually happened was that she shredded the fuckin’ thing like it was made of paper. Whatever, at this point the mess was big enough that it was basically a lost cause anyway. Might as well add a destroyed door to the list of damages. Heather shrugged and then pulled what was left of it apart so that she could quickly duck into the lab.

Heather took a brief look around, but only a brief one. It seemed like this was specifically a botany lab, given all the plants. The room was full of the fuckin’ things, more like a greenhouse than a lab. Mostly small potted flowers, though there were several watermelons of all things? Big ones, too. Not quite the kind that you’d see at a county fair winning a biggest watermelon prize for being the size of a small child, but big enough to at least get an honourable mention.

Heather idly picked one up and smirked as she confirmed her earlier comparison. Her biceps and boobs alike were, in fact, both the size of watermelons.

She didn’t get much of a chance to compare, though. Another muscle spasm surged through her body and her fingers flexed on their own. If a steel door had been like paper in the face of her grip strength, a fruit might as well have not even been there. Sticky, pinkish red juice flowed down her dark fur, and the remains of the watermelon fell to the floor. God, and that was just an idle flex of her fingers. Another grin spread across Heather’s face as she idly glanced at the remaining watermelons. She had a lot of muscles and she wanted to test the strength of each and every one.

After she finished transforming, of course. At this point, the only thing left was her hips. The last remaining shred of her humanity – and, for the most part, she couldn’t wait to be rid of ‘em. A small part of her, that tiny remaining fragment of Hans, was a bit apprehensive, and Heather couldn’t really blame that part of herself. She was more than happy to be a horse, but she was gonna miss Little Heather. Girls don’t have dicks, after all.

Although, on the other hand, it wasn’t like she was an ordinary girl. Again, this was furry shit, and while she’d never dipped her toes in that side of the internet, everyone knew the stereotypes. She’d resigned herself to being emasculated, but maybe – just maybe – she’d get to have her cake and eat it to. The sweltering heat hit a climax, made even worse by the humid atmosphere of the botany lab. Her fur glistened with sweat as her breathing came faster and heavier. “Oh fuck. Oh fuuuuck,” she groaned. Her bones creaked and cracked, reshaping wider and much, much bigger. Flesh and muscle bubbled into existence, giving her an ass that rivalled her chest. Her spine erupted out of her body into a luxurious black tail that immediately got to twitching wildly as the pleasure mounted and mounted and mounted, building and building and building to an inevitable climax.

She dimly registered the sudden emptiness just beneath her balls. Normally that would have been a more pressing concern, but her cock understandably monopolized her attention. She fell back onto her ass, hips bucking hard enough to crack the floor beneath her as she came and came and came. Each gout was more copious than the last, because with each gout her cock and balls alike got bigger. She wasn’t sure how long her climax lasted, but probably a fuckin’ while. At some point her dick had stopped growing, but she didn’t really mind all that much considering the thing was the size of her entire-ass arm, shoulder to fingertip. Thick, cylindrical, pink at the base but slowly fading to dark brown at the bulging circle around the middle and a massive flared head, fed by balls the size of her fists. A part of her was sad that she didn’t have another set of watermelons, but considering how thoroughly she’d coated the botany lab with her output she figured that if she did have watermelons she’d still be going.

“Mnf. Speaking of watermelons.” Heather idly grabbed one off the counter and placed it in the crook of her elbow, and then destroyed it with an idle flex. “Not too shabby.” Heather idly remembered reading somewhere that watermelon rinds are pretty comparable to human skulls when it came to this kind of thing, but given how little effort it took to destroy it she decided to abandon that line of thought, instead grabbing another watermelon and placing this one just below her balls. “Always wanted to try this,” she said, though admittedly in her fantasies she hadn’t been the one effortlessly popping a watermelon with her thighs. God, if anything it was even easier than with her biceps. Probably more because of the better leverage and the fact that she was using two limbs rather than her strength being concentrated in her lower body, although on the other hand she noticed that she was somewhat lacking in the pecs department. Oh well, that just meant they didn’t get in the way of her tits.

“Would’a liked to crush a melon with my melons, though,” she muttered. “Though I guess I do have one more set of melons to test out...” Slowly, Heather pulled herself to her feet – only to pause briefly as she adjusted her posture so as to not bump her head on the ceiling. God, how fuckin’ tall was she? The labs’ ceilings weren’t exactly low, and she couldn’t stand up straight without bumping her head. That’d put her at more than nine feet tall, which was frankly ridiculous. Way too fucking big. “Hell yeah,” she said with a grin, picking up a third watermelon and sliding it in between her asscheeks. “Ha! Look, ma’, no hands necessary!” She hadn’t actually expected her ass to have the grip necessary to hold up the melon, but she wasn’t gonna complain. With a final smirk, she flexed. There was a wet pop and suddenly the inside of her ass was very sticky.

“... That’s gonna be a bitch to clean up, isn’t it?” She’d already given up on her integrity around when she dropped the bags and they burst all over the hallway, but she had fur now. It was going to get all sticky and matted and disgusting, and there weren’t exactly personal hygiene facilities in a government funded lab. “Darn, guess I’m gonna need some help,” she said as her mind wandered back to the triplets and her cock twitched eagerly. She reached down to the remains of her pants and picked up her walkie talkie. “Hey, it’s me. I’m gonna need those rags I asked for sooner than I expected.”

“.. Who is this?”

Shit fuck right her voice was different. She coughed conspicuously and did her best to speak in a lower, rougher register. Faking her old voice as best as she could, which was honestly not very well. The downside to being younger and sexier, she supposed. Oh well, hopefully she could make up for it with raw charisma. She sure had a lot of it to spare. “It’s Hans. Sorry, my radio’s being fucky.”

“Okay,” she said, though she was clearly not entirely convinced.

“Look, d’ya have the rags ready or not? Because things have gotten a lot more complicated and a lot messier.”

“Okay, okay, geeze, the rags are ready.”

“Good. Bring ‘em-” Heather paused, very briefly, before continuing. “Bring ‘em to the courtyard, we’ll meet there.” This lab was probably very slightly closer, but Heather was sick and fucking tired of hitting her head on the ceiling. “Bring the others, too, this isn’t a two man job.”

“Yes’m,” the triplet said. She still sounded dubious, but there was something else about the tone of her voice, creeping in from the edges. She was horny. Just from Heather’s voice. Fuck, Heather was horny just from Heather’s voice. It was nothing like the gruff middle-aged man with a smoking habit that she had been not half an hour ago. Higher pitched, but still low for a woman. Husky and sexy, sweet and smooth, like hot chocolate. The good shit, too, the kind made by melting an 80% cacao bar in some hot milk. Fuck, she had to fight not to cum again right then and there – though, perhaps, that was her libido talking.

She grinned, tossing the radio aside and made her way over to the botany lab’s door, only to be hit with one final complication – she was too buff to fit through. It wasn’t a hard complication to deal with, though. She pressed her hands on either side of the opening and pulled, effortlessly tearing out huge chunks of wall. “There we go,” she said with one final confident smirk as she squeezed her way out into the hallway. “Time to break Little Heather in for real.”

~~~~~~

Jan’s output was, it turns out, absurd. Well beyond what she had really intended it to be, and frankly pushing the limits of what was credibly physically possible. Especially considering that this wasn’t her first climax of the day. Or the second, or third, and definitely wasn’t the last – she was still rock hard and ready to go despite doing multiple output tests. Which was one hundred percent Mike’s fault. She wasn’t going to even pretend that it wasn’t. He’d spent the entire time latched on to her crotch like a remora, ‘providing stimulation’ for the tests. Really just an excuse to worship her balls a bit more, face buried deep in their cleft.

“You know, you’re probably skewing the results.”

“Mnf.”

“Well, I care that they’re accurate. I know we’re doing an aggregate measurement to get the average, but that doesn’t work if you skew every shot above the average by shoving your face in my crotch.”

“Mnf.”

“Yes, I know it’s your present. That should make you even more invested in accurate measurement because there’s still plenty of room to improve the formula.”

“Mnf.”

“You’re only saying it’s perfect because you’ve got your face in my nuts. Trust me, once I actually implement the improvements, you’ll be glad you let me get accurate measurements.”

Mike pulled away from her crotch, taking a deep breath of relatively fresh air. “Are you sure these ‘improvements’ are going to be noticeable to anyone other than you?”

“Yes.”

“I don’t believe you.”

“You’ll notice them!”

“You always say that and then you actually make the improvements and they’re like point zero zero zero zero zero one percent more efficient or something. Stupidly small incremental improvements.”

“I’ll have you know that those ‘stupidly small incremental improvements’ add up really quickly.”

“And you can do them on your own time. I wanna enjoy my anniversary present.”

“Fine. I can do my measurements later.”

“I think you’re literally the only person in the world who can get presented with this and think about measurements. I think you have a fetish for measurements.”

“I’m a scientist.”

“Yes, well, I don’t have a fetish for measurements so science can wait until later. Right now I want to play around with your fat horse nuts some more.”

“Have you considered maybe enjoying some of the other aspects of my new body?”

“No.”

“I swear to god I might as well have not bothered with the tits or ass.”

“The tits and ass are important! Just because I’m not using them doesn’t mean they don’t contribute!”

“I don’t think you’ve even looked at them yet.”

“I have! When I got here!”

“Yes, and you haven’t spared them a glance since.”

“I have too!”

“I would be more inclined to believe you if you were looking me in the eye and not laser-focused on my balls, dear.”

“Well okay yeah, I’m looking at them now.”

“Why don’t we take a break.”

“Are you saying you can’t keep going?”

“No, but you have much less stamina than I do. I’d like to get some too, eventually, and I don’t want you spending it all jerking off to the smell of my balls.”

“I can keep going.”

Jan held up a hand. “Five minutes.”

“... fiiiiiiine, five minutes.”

“Thank you.” Jan slid off the measurement platform and sat down against a wall. Mike, meanwhile, flopped down face-first into a pile of cum. “You’re insatiable.”

“Mnf.”

“I’m supposed to be the one with the chemically enhanced turbo-libido, not you.”

“I’m a man of simple tastes.”

“That can’t possibly be comfortable.”

“It’s not. It’s hot and sticky and kinda tingly?”

“Then maybe get out of the cum?”

“Nah.” Mike rolled over. “I’m basically coated from head to toe at this point so getting out of the cum is just gonna make me get cold faster. At this point it’s stay right where I am or the emergency shower.”

“Or the sink.”

“The sink would take too long! Are you sure you don’t have some kind of bathing facility in here? A locker room or something?”

“What do you think we are, a gym?”

“I dunno, you might have a gym for all I know.”

“We don’t have a locker room. The only showers we’ve got are for decontamination.”

“Maybe we should have done this at home.”

“And then have to clean up after ourselves, yes.”

“We could hire a cleaning service.”

“With our own money? To say nothing of all the stuff that would definitely get irreparably damaged in the process.”

“Okay, fine, I can probably handle a decontamination. Later.”

“Anyway, there is another option besides cleaning up or wallowing in semen.”

“There is?”

Jan patted her lap. “We could cuddle.”

“Are our five minutes up?”

“We could cuddle without fucking.”

“Fiiiiine.” Mike got up and made a brief, mostly futile effort to wipe off some of the excess horsecum that was thoroughly coating his body. There was so much of it, and it was so thick and viscous and sticky that he mostly just managed to spread it around. “Sorry, I’m gonna be kinda gross.”

“You say that like I’m not also covered in cum.”

“Fair enough.” Mike walked over and settled into Jan’s lap, straddling her cock and resting his head against her tits like they were big, soft, furry pillows. “Hey, do you milk?”

“I could, if you wanted.”

“Mmm, fair. I can see it being a bit inconvenient in day-to-day life.”

“It might be fun to try. You’re paying for the waterproof bras, though.”

“Boooo.” Mike settled in, letting himself sink deeper into her lap and  pressing his crotch against hers. “Maybe a little frottage.”

“We’ve still got two minutes.”

“Boooo.”

Jan rolled her eyes. “Fine, fine. It’s not like we can avoid it with you in my lap anyway.”

“You’re huge, by the way.”

“We’ve got strap-ons about this big.”

“Yeah, as a joke. This thing’s as big as my torso.” He pressed more firmly against it, as if to emphasize his point. “It’d take like ten of me to make one of you.”

“Six,” Jan replied. “You’re a sixth of the length of me.”

“Yeah, yeah, rub it in.”

“You’re the one underestimating yourself.”

“And you’re the one directly saying that I’m five inches.”

“Lots of people are five inches.”

“And you’re not one of them.” Mike pressed his body even more firmly against her shaft, wrapping his arms around it before beginning to firmly thrust his own cock against it.

“You’ve still got twelve seconds.”

“Consider it making up for being thirty five seconds late. Besides, I’m really fuckin’ horny all of a sudden.”

“I can’t imagine why,” Jan said, rolling her eyes.

“No, I mean like more than I probably should be? And I’m still tingly.”

“Hm. Interesting.”

“And, like, really hot.”

“Mmm.” He wasn’t kidding. She could feel his body heating up against hers, even through the fur. “Odd. You seem to be sweating a lot, too. Probably from the increased body tempera-” she paused, frowning. “Wait. Where did all the cum go?”

“Fuuuuuuuuck!” Mike cried as his cock abruptly grew. Jan could feel it pressing against her shaft. Five inches had become about ten.

“Hm. Unexpected reaction to my semen. Pupils dilated, heartrate elevated, increased body temperature and excessive sweat production, visible swelling.”

“Mnnnn I wouldn’t call that swelling baaaaaaahnnnn~” Mike cut himself off as his cock grew again. Not quite as catastrophic as the first time, just enough to hit a roughly even foot, but it also got noticeably thicker, the flesh darkening and bulging oddly.

“I think I see what’s happening, but further observation is- hm?” At first, Jan thought it was more sweat, but something told her that wasn’t the case. “Sorry, honey, I’m going to have to get you off of me for a moment.”

“Mnnnnn fuuuuuuck.” He didn’t object, at least not specifically, but he did wrap his arms very tightly around her cock.

“Ugh, fine, you insatiable slut.” Jan rolled her eyes before reaching down and slipping a hand underneath his body, pressing just behind his balls and then slipping inside his new vagina.

“Aaaaaaaahnnnnnnnnn!!!!”

“I thought so. Physical changes are not limited to the growing phallus. Quite possible we might see a full transformation.”

“Mnahhhnnnnn~”

Mike’s cock lurched bigger again, thick and dark and decidedly equine. It wasn’t alone, either – his balls swelled, fat and full and heavy, coated in a thin layer of pale fur. Jan gently hefted one with the hand that wasn’t busy fingering him. “It’s hard to get an accurate estimate but you seem to be about as big as I am right now, which should mean that you’re-”

“Fuuuuuuuuuuuuuuuck!!!!!”

“- not done growing at all, it seems.” Jan decided it was probably prudent to stop fingering Mike for now. As appealing as it was to fuck him while he grew, it also seemed to be making things worse. Or better, depending on how you looked at it. It was definitely spreading, faster than it had been before. White fur, coating his hips and inching down his legs and up his back. Otherwise he hadn’t actually changed all that much, certainly less dramatic than the proverbial elephant in the room. His hips were wider and his ass was fuller, but just barely enough to be noticeable. She wasn’t yet certain if that was the result of him having a bigger baseline than her or if it was the result of the same variance that resulted in his cock being significantly larger than hers. She needed more data. “I’m going to try and speed things up. Hold on.”

Jan removed her hand from his balls, slowly moving it up to grasp his shaft. One hand wasn’t enough, but it’d have to do for now because she wanted to also keep giving his other bits attention. Thankfully, she could make up the difference with some frottage. Maybe. She was honestly winging this, just a bit. That arousal triggered the change was just a hypothesis right now, and one that she was already starting to rethink. She was going fairly hard, but it hadn’t actually triggered any of the more dramatic transformations. “Maybe it has to be sudden spikes of arousal, then? Or perhaps I have it backwards, and the transformation results in arousal. I definitely had to fight not to cum when I transformed. Need more data.”

“Honey with all due respect now’s not the time for more fuuuuuucking data!”

“There’s always time for more data. I have another hypothesis.”

“Aaaaaahhnnnn!” Another surge of transformation, this time spreading all the way down to his knees. And there was a long way to spread. His bones creaked and groaned as they thickened and lengthened disproportionately to the rest of his body – and disproportionate to her body as well.

“Interesting. At this rate you’ll be significantly taller than me when you’re done.”

“Mnnnnnn.”

“Anyway, hypothesis; I believe that my semen contains traces of the formula and that’s the cause of the transformation. The reason it’s taking so long is because you absorbed it via contact rather than actually ingesting it, so-”

“So all I’ve gotta do to speed this the fuck up is suck your cock, got it.”

“Wait-”

To the surprise of exactly no one, Mike did not wait. He lunged forward, wrapping his mouth around Jan’s flare as much as his body was physically capable of. Which was a lot more than Jan expected, but still only a fraction of a fraction of a fraction of her whole length. He made up for it by putting his whole body into it, wrapping his thickening thighs around the base and squeezing, grabbing the top and pumping it, shoving his own massive shaft aside so he could press his entire torso against the damn thing. “I wasn’t finished,” Jan whined, in time with a burst of precum. The only response she got was another muffled grunt. “I was going to say that obviously in addition to there being traces of the formula in my semen, it’s become unstable.”

“Mnf.”

“You should care because there’s a big fucking pile of the stuff right outside of the lab!”

“Mnf.”

“I would very much like to be able to cum without turning people into horses!”

“Mnnnnnnfffff~” Okay, well, obviously she wasn’t getting through to him. On the plus side, it seemed her hypothesis was correct this time – directly sucking her cock did in fact seem to be speeding up the transformation. His mouth slid its way down her cock as his torso started to lengthen.

Which also made their current position a lot less comfortable. Thinking fast, Jan allowed her body to slide down the wall until she was lying down, and Mike in turn quickly slid from pressing up against her cock to practically lying on top of her, with his ass in her face. “Well,” she muttered to herself. “Don’t mind if I do.”

“Mnffffffff!!!!!!!!!” The extra stimulation was, apparently, enough to get Mike all the way down to the hilt. Perhaps it was a combination of direct exposure and spikes of arousal, then? Jan would have to run further tests. After she finished with Mike. She shoved her face and tongue in deeper, or at least as much as she could with a horse face. Actually, that probably explained why he could suddenly take two and a half feet of cock – longer face. She couldn’t tell for sure, though, because the only thing she could see was Mike’s fat horse ass. It wasn’t even all that fat, even proportionally, but it was right in her fuckin’ face so she couldn’t see anything else. She had to rely on feeling to get a vibe of how his transformation was progressing.

And most of what she felt was his monster cock. It felt like every time his transformation progressed, it got a bit bigger, as though it wasn’t already huge. God, how big was it even going to get? Like a tree trunk strapped to his waist. And that wasn’t even factoring in his fat, full balls. They pressed into her tits firmly, very nearly matching them in terms of raw size – and getting slightly but undeniably bigger with every throb, every pulse, every buck of his hips. God, it was huge. He was huge. She could feel his body weight pressing more and more against her as he got bigger and bigger. The sweet taste of his femcum. The way his cock pulsed against her body. The tight undulations of his throat. She tried to keep her analytical mindset up, but she just fucking couldn’t. She pulled her face out of his ass, as much as possible. “I’m gonna-”

There was a wet pop as Mike pulled away from her cock. “N-not yet,” he said. Although he sure didn’t sound like a he anymore. That was not a man’s voice that came out of his mouth. Fuck, he even had girl bits. Mental changes weren’t off the table at this point. Maybe he was a Michelle now? She’d have to ask him later. Right now, she had other concerns – and she was pretty sure he did, too. He moved smoothly and quickly, obviously just as put-out about the sudden cessation of stimulation as she was. “I want you to cum inside me,” he practically moaned, shoving his balls aside and then plunging down to take her cock inside of him. Even as a horse, he was still an incurable bottom.

Which was, admittedly, less extreme than it had been pre-transformation. Now that she could actually see him, she could make a more concrete estimate of his size. Maybe nine feet tall? A good foot and a half on her in terms of height, then. And, obviously, as she’d already observed numerous times, his dick was equally absurd. She had a hard time estimating exactly how big he was down there, given all the enthusiastic bouncing he was doing on her shaft, but it was big. Beyond just big. It probably came up to his head, maybe even above it. Everything else was a bit more modest, at least by the standards her own body set. He was willowy, almost but not quite lanky. Slender, though with just enough muscle to be noticeable. Pert and perky D-cup tits bounced up and down in time with his relentless fucking, coated in perfect white fur – only broken up by his long, blonde hair and his jet black cock. And nipples, she supposed. And his eyes too, but listen she was having a hard time thinking straight okay?

That confusion was justified – literal seconds later, she came. Copiously, as was the case with every one of her climaxes so far. Most of it didn’t actually end up inside of Mike, though that wasn’t for lack of trying on his part. It was just that the sheer enthusiasm of his bouncing ended up with most of it splashing right back out, painting the floor and her hips with even more sticky off-white goop.

And then Mike came. And Jan found herself having to rethink her definition of copious because holy shit it was a lot. Those massive balls weren’t just for show. Likely they worked just like her own cumtanks. Not just big, but dense and absurdly productive. Except scaled up from fist-sized to head-sized. The end result being an absolutely absurd volume of semen. Just, like, comically copious. Gallons, maybe even beyond gallons. Like a fucking fire hose or a geyser or a volcano or any of those tried and true metaphors, except this time it wasn’t hyperbole, it was actually happening. It wasn’t just the volume, it was the length. Cumming and cumming and cumming, and then cumming some more, on and on and on, for what felt like hours, splatting on the ceiling with a wet plapping sound like hitting a wall with a wet towel before splatting down on the ground below them. Painting the ceiling, the floor, even the fucking walls with the way it flailed about, going and going and going for what felt like hours and honestly might very well have been hours.

“You’re cleaning this up,” she said once he finally finished.

“Hey, whose fault is this.”

“Yours.”

“You’re the one with the tainted cum.” Mike stood up – or attempted to, but was cut short by bumping his head on the ceiling. “Ow, fuck.”

“We’ve got bigger concerns than low ceilings. How long has it been?”

“I don’t know. You’re the one with the absurdly accurate internal clock.” Mike rubbed his head. “Check your computer? Assuming it even still works. I hope all your tech shit is waterproof.”

“Mike, do you seriously think that I would turn myself into this and not think to waterproof everything.”

“Mm.” Mike frowned slightly, which reminded Jan of something.

“Michelle?”

“Maybe. At least until we undo this.”

“You want to undo this?”

“Well, I mean, it’s hot and all, but it’s also gonna be super inconvenient in the long-term.”

“We can go with Michelle for now. I’ll have to look into the mental changes. And also the tainted cum, dammit.” It was Jan’s turn to frown as she got up. “I knew something would go wrong, but this is bad.”

“It is?”

“That big fucking mess we left out front, remember?” She scooped up some cum and waded her way through waist-deep cum over to some sort of machine or another on the desk beside her computer. God, and she had worried about how overly productive she’d made herself. It was absurdly viscous – every step forward was a fight, making the journey across the room take an appreciably longer time than it normally would, especially considering that she was seven feet tall. Thick and heavy and virile. Absurdly virile. She would have to measure the spermcount in addition to everything else, but she was pretty sure that just being in the stuff as long as she had was enough to knock her up. She could feel it, a weird sort of nagging itch inside of her. “I’ll run some quick tests on this stuff, you get on that platform and measure yourself.”

“I don’t know if that’s in the cards.”

“Look, just stand on the thing and say ‘weight’ and ‘length’. We can figure out the rest later.”

“Yes, ma’am.”

Jan put the cum in the machine and pressed some buttons before turning her attention to the time. “Twenty eight minutes. Fuck.”

“Twenty eight what-now?”

“That’s how long you came for.”

“oh. Uh, it says that I’m two hundred and thirty eight kilograms?”

“That’s about five hundred and twenty five pounds.”

“what”

“Makes sense, you’re visibly leaner than me so it logically follows you’re not that much heavier than I am. But you are significantly taller, and mass is skewed further by your, ah, bigger manhood. Speaking of which, don’t get distracted.”

“Oh, right. Length? It says one hundred and sixty seven point six four centimeters, what is that in real people measurements.”

“Five and a half feet.”

Michelle frowned. “That can’t be right, I obviously grew way more than half a foot. Maybe it’s busted from all the cum, or maybe it’s because I’ve gotta hunch o-”

“Honey that’s the size of your cock.”

“what”

“You’re packing heat, hon.”

“That is way too much.”

“This coming from you.”

“Hey, don’t get me wrong, I’d probably be down for a five and a half foot horsecock on you. I’m a size-queen but that doesn’t mean I want to be the size.”

“We’ve got bigger issues than your fetish. I’ve figured out what the problem is.”

“Try not to get too technical.”

“Layman’s terms, then. I was right, we’re contagious. Horse is an STD now.”

“Okay. That sounds... potentially problematic.”

“It’s actually worse than it sounds. There are traces of the serum that turned me into this in my semen, but – as evidenced by the differences in our proportions and sizes – those traces are unstable. And, as you can probably guess, there are also traces in your cum.”

“Okay, that’s gone into very problematic territory.”

“The good news is that there is a lot less of the serum in your semen than in mine. We can safely extrapolate that to future generations – fourth or fifth generation horses are likely to be completely devoid of the serum and thus not contagious. Which means that so long as I’m the only first generation horse, it shouldn’t be too hard to keep things under control. We just need to make sure to make as few second generation horses as possible. Ideally just you.”

“Okay cool but you said that’s the good news,” Michelle said with a frown as she walked over to the computer.

“Remember when I said that the serum in my semen was unstable? The bad news is that yours is even more unstable.”

“Oh. That’s, uh.”

“Extremely problematic.”

“Yeah. That.”

“There’s no guarantee that the serum only transforms humans. We do our best to keep things sterile, but there’s still lab animals and samples to worry about. I trust you to be able to keep it in your pants outside of situations where we can properly dispose of the biohazard, at least until I can fix this, but not a lab rat. To say nothing of bacterial or viral samples, I really don’t want to accidentally create a hyper-contagious horse virus.”

“Well, you said the lab’s sterile, right?”

“Yes but no sterilization process is going to be perfect, especially when it comes to mutated strains.”

“I mean, so long as we can keep the cum in this room until you fix it-”

“Hallway.”

“Shit. Fuck, okay, how long do we have until the janitor gets here again?”

“There’s some more good news. It’s only been about forty five minutes since we started, which means we have exactly fifteen minutes to deep clean and sterilize my earlier mess.”

“Ugh.”

“It’s fine, it’s fine. I can call up the janitors and warn them that there’s a serious biohazard in this general area and then take my time to engineer some sort of cleanup robot. You go check on the hallway.”

“Yeah, okay.” Michelle made her way over to the doorway. “I guess this means I’m gonna hafta stay cramped and crouched?”

“Yes. It would be very easy for things to spiral out of control, but yes as of now that hasn’t happened yet. We need to be extremely cautious about that yet, is the thing. There’s lab animals, there’s microbes, given that the serum takes longer when exposure comes via the skin than via ingestion it’s entirely possible that your cum is going to result in me transforming further and we don’t know it yet.”

“Annnnd there’s the possibility that someone’s already messed with the cum outside?”

“Yes. Which is why no, we’re both going to have to stay in the lab until I synthesize an antidote.”

“Yes, ma’am.” Michelle pressed the button that opened the door, and had to then kneel down in order to actually see out. Jan idly noticed the cum-level appreciably lowering, though not quite as much as you’d think. It oozed out of the door slowly, a testament to just how thick it was. “Shit.”

Jan cringed as she realized that they’d just spent like a full minute actively tempting fate. “Don’t say it. Don’t even say it. I know what you’re going to say and I do not want to hear it right now.”

“There’s bags of the stuff.”

Jan let out a slow, exasperated breath. “Murphy’s god damn Law. How’s the damage?”

“Like I said, bags of the stuff. Someone started cleaning up.”

“Shit.” Jan put her phone down. There was no point calling the janitorial staff because obviously they’d already fucking been here. She made her way over to the door and sure enough there were, in fact, bags of the stuff. Enough bags to not nearly hold all the cum that wasn’t at the scene, as evidenced by the set of cummy footprints leading off towards the organic material disposal site. “Shit shit shit.”

“Ah! Wait for me!”

Really, she probably should have had Michelle stay behind. It was entirely possible that things were still under control, that the janitor had worn a watertight hazmat suit and had been smart enough to wait to ask her what the safe procedure was before disposing of the cum. There was still the chance that she could fix this, and so she should probably have acted like she intended to fix things. But, deep in her heart of hearts, Jan knew that if that were the case then he would have already fucking asked her.

Sure enough, about halfway to the disposal facility they came across evidence of what had happened. Several large splotches of cum where someone had dropped the bags, topped with the tattered remains of a custodial jumpsuit. More cumprints, this time barefoot, led to a nearby botanical lab. Jan could tell that it was a botanical lab because someone had torn the door open and the resultant hole was completely clogged with vines. Big, thick, vines that were visibly throbbing bigger and thicker and were leaking some sort of milky sap and were suspiciously horsecock-shaped because of fucking course they were.

Jan paused, but only for a moment because there were even more footprints to follow. “Right. One fucking disaster at a time.” She could already guess exactly where these were heading, because it was probably the worst place for them to head in the current situation and so of course that’s where the janitor would go. The footprints were joined by a trail of precum that got more messy and copious as they got closer to the courtyard. And Jan, for her part, somehow managed to get more panicked.

The door to the courtyard was already open. And, of fucking course, the worst case fuckin’ scenario was playing out right in front of Jan’s eyes. The entire custodial staff were accounted for, although one of them was a horse. Not quite as tall as Michelle, though still tall enough to bump her head on the ceilings, and obviously her dick wasn’t anywhere near as absurd. She was still almost certainly the biggest of the currently three horses, at least in terms of raw mass. In short, she was beefy as fuck which was honestly kinda hot but not hot enough to overcome Jan’s ongoing panic. Especially thanks to the rest of the janitorial staff. Triplets who were currently sucking Hans’s dick. And, somewhat more pointedly, who had just finished sucking Heather’s dick.

“Ah! Doctor Takamura, right? You and I need to have some words about basic fucking hygiene!”

Jan pinched the bridge of her snout. If she were just going by the voice, she would have no idea which of the janitors was speaking to her. Michelle just sounded like Mike but as a girl, but this woman decidedly didn’t sound like her pre-horse self. It was only process of elimination that gave it away. “You weren’t supposed to be anywhere near my lab until five minutes from now, Hans.”

“I was ahead of schedule! Also I’m Heather now, by the way.”

“Of course you are.” Jan furrowed her brow and pinched even tighter. “You’re probably going to want to get out of the blast zone by the way.”

Heather frowned. “What’s that supposed to-”

There was no slow burn this time. Of course there wasn’t, the three of them had ingested enough cum that their bellies were visibly swollen. They all slid off of Heather’s cock and onto the ground, writhing and moaning and changing. Jan’s eyes darted from girl to girl to girl in a futile attempt to take it all in at once. Impossible, of course. If it were just one, then maybe she might have been able to keep track of things. But three? Not a chance, especially considering how fast they were transforming. They already looked to be more than a match for Jan, and they were very clearly not done yet, not by a long shot. If the second generation were bigger than the first generation, of course the third generation would be even bigger than that.

By, like, a lot, it seemed. Jan’s eyes darted back and forth, from boob to butt to cock to nut, swelling and sloshing and jiggling and bloating and growing and growing and growing. Bigger than Jan. Bigger than Heather and Michelle. Bigger than some buildings, fuck. Every time she tried to settle in on looking at one of the triplets, another drew her attention. One clutched at her head sized breasts just in time for them to quintuple in size, dominating her torso and jostling up against the equally massive lower pair, milk spraying from coke can sized nipples and soaking into cowprint fur. One aggressively jerked a cock big enough to make Michelle’s look reasonable and which itself in turn was made to look reasonable by balls big enough that they touched the ground and that were still growing, spreading her legs and lifting her up, so absurdly fertile and productive that they couldn’t hold it all, thick off-white spunk oozing down the length of her shaft and sinking into soft, pink fur. Cow horns, bunny ears, milk, cum, mooing and moaning.

And then there was the third triplet. Breasts smaller than the cow-horse’s, balls smaller than the bunny-horse, not as muscular as Heather or as cocky as Michelle. No, she was just big. Lying down on the ground, her hips rose and then fell and then rose higher and fell harder, each thrust creating a louder and louder thud that turned into a crack as she shattered the pavement beneath her through the sheer force of her fucking. Her limbs spread across the courtyard in awkward lurches, feet upon feet of size at a time as she convulsed and moaned. The lab’s windows were thick, robust things, made of high-tech reinforced glass, designed to resist whatever might go wrong with all the mad science going on in there. The most durable glass in the world and the things fuckin’ rattled and cracked like they were nothing.

And the bitch was still growing, too. The courtyard was not exactly small and she was already big enough that her head was bumping up against one end and her feet against the other, blocking off Jan’s view of the other sisters. And, somewhat more concerning, leaving her trapped in between two very big and very dangerous looking feet and separated from Michelle and Heather. At least until, with another surge of size and an involuntary twitch of her leg she ploughed through one of the walls, leaving a nice big hole that they could probably fit through. And she grew some more, forcing her legs to lift up into a kneeling position and making the other two visible again before then getting even bigger.

Jan had absolutely no idea how big she was when she finished, and honestly was only guessing that she was finished at all, evidenced by the fact that all three of them came. Copiously. Enough to make Michelle’s earlier cumshot seem normal. And, somewhat more pointedly, in the case of the biggest horse it was enough to thoroughly break containment by virtue of her sheer fucking size, erupting upwards like a volcano. It rained back down, not just completely coating Jan and likely the others but contaminating the entire fuckin’ tri-state area with third generation cum that, according to Jan’s calculations, was almost certainly still extremely contagious. Great. Just great. Hopefully she could at least convince these three to hold it in for now, and then if they were very lucky the serum would be unstable enough that the fourth generation horses wouldn’t be contagious. And she’d only have to worry about the inevitable wonton destruction that horse hybrids even bigger than this might cause. Ugh.

The third horse slowly pulled herself into a sitting position, giving Jan a good look at the other changes besides just being colossal. Proportionally, she had roughly the same figure and physique as Jan, just scaled up to be like fifty or sixty feet tall. Maybe more. Fuck. Fuck. That was about where the similarities ended. This girl was not a horse – or, at least, much like her sisters she wasn’t just a horse. Horses didn’t have big fuck-off claws the size of a person on their feet and hands. Horses didn’t have big, leathery wings with a wingspan that would have put the fuckin’ spruce goose to shame. Horses didn’t have big, spiralling horns. Horses didn’t have sharp teeth. Horses didn’t have green fur, and their fur certainly wasn’t broken up by patches of fucking scales.

“Okay,” she said, taking a few deep breaths. She seemed disoriented, which made sense. The transformation was already kind of a lot when it was just growing to seven and a half feet, let alone turning into an outright giantess. “Ugh. Can’t think straight. I’d better be getting some fucking hazard pay for this shit.” She glared down blearily at the courtyard before reaching over and effortlessly picking Jan up. “You,” she said, voice loud enough that she could probably be heard for miles around. “I’m too horny to think straight. Make me cum.”

“That’s actually a really bad id-”

“Sorry I can’t hear you you’re too tiny.” There was a loud wooshing noise, the sound of air rushing past her as the dragon-horse casually placed her on her nose. “There, you’re closer now. What are you on about and why is it more important than how horny I am?”

“You’re contagious.”

“Obviously,” the dragon-horse replied tersely. “And that’s... my problem?”

Oh dear. Jan was starting to get an idea of exactly what kind of person this was. Idly, she looked back down at the other two triplets, just for a moment. It was hard to say for sure what, exactly, was going on because they were so far away, but she could get the gist. The lacquine was masturbating furiously despite the fact that she had not, in fact, stopped cumming yet, eagerly swallowing her own cum which was likely very bad. Heather was currently trapped underneath the pink bunny-horse’s gigantic nuts and looked very put off about it until the cum reached her, coating what little of her was visible. They were too far away for Jan to hear what the bunny-horse was saying clearly, but she knew enough lip reading to pick up on “fuck” and “cum” and “breed,” over and over again like a sex-crazed mantra. Meanwhile, the cow-horse had already gotten to work giving Michelle a titjob-blowjob combo in between motherly coos. Also probably bad, though at least Michelle’s cum wasn’t as unstable as the bunny-horse’s. Still, Murphy’s law had repeatedly demonstrated just how real it was today so Jan was fairly certain that ingesting more serum would absolutely change them again, so she had to think on her toes to come up with some way to get this situation back under her control.

“Well, for starters, it’s not just contagious to humans. Animals, plants, bugs, even germs. It’s entirely possible that at this point you’ve created a highly contagious supervirus that is going to turn the entire world into horses.” Of course, she didn’t know that last bit for sure. But the dragon-horse didn’t need to know that.

“You’re not making a good argument here. This shit’s great, the way I see it spreading the gift around is just altruism. Maybe I’ll even make someone almost big enough that I can get my dick wet without killing ‘em.”

“Ah, but you see, with each generation of transformee the contagion gets more and more unstable. Which means that anyone transformed by your cum is going to be bigger than you are, and the fourth generation – like, for instance, this highly contagious horse transformation virus – is going to make people even bigger than that.”

“Ah, I see what you’re getting at. And you’d know this because you’re patient zero, then?”

“Yes.”

“Okay cool. Well, obviously anyone being bigger than me is unacceptable. So.” Once again, she grabbed Jan, wrapping her hands tightly around her. “I’m gonna take you over to your lab, and you’re going to make something to make me bigger. Bigger than anyone and everyone forever. And if you don’t then I am going to eat you whole and see if the residual horse transformation juice in you is enough to get me what I want. Are we clear?”

“Crystal.” Honestly, not too bad a deal. Jan liked the part where she didn’t get eaten alive. Part of her wanted to take this opportunity to make a cure. It wouldn’t be hard to do, given that the dragon-horse probably wasn’t experienced enough with mad science to tell what she was doing. And, well, Jan seriously considered it. But, well, there was one thing that she hadn’t taken into account when all of this started, and it was starting to rear its ugly head. There were hints of it with the change in Heather and Michelle’s gender identities, and even bigger hints from the triplets – she was pretty sure that the dragon-horse didn’t have a god complex before her transformation.

Simply put, the transformation had clear and obvious psychological effects in addition to the physical ones. And right now she was starting to feel her psychological changes because when she considered actually making an antidote, she found that she didn’t really want to. In fact, the thought of making the dragon-horse – and, by extension, herself – bigger sent a tingling feeling through her body.

Or maybe that was just the effects of Michelle and the dragon-horse’s cum starting to kick in. Either way, her day was about to get a lot more interesting.