Rotor stared at the terminal as if his glare would convince the collection of circuits and wires to produce the information he wanted to see. Rotor was one of a handful of Mobians associated with the Freedom fighters who had any kind of medical training and so coupled with his technical skill he was the one assigned to examine certain records. So far he had found a trend but not a definitive explanation as to what was causing it. The Population of New Mobotropolis, Knothole and the whole of the Kingdom of Acorns was nearly a third of what it was when the last proper full census had been taken. There was a fairly obvious cause for that seeing as the last census had been performed roughly a year before Dr.Robotnik had struck.  What was less explicable was how in the two decades that followed that number had not recovered and in fact was continuing to decline.


“There has to be a factor I'm not seeing here…” Rotor said, removing his glasses to rub his eyes. 

“Fertility and or Virility rates falling off.” Rotor jumped in his seat as Tails spoke, due to the walrus having not heard the lab door open. “Oops, snuck up on you again. Sorry!”  Rotor rubbed his neck which was shooting with pain. Sudden starts like that agitated his spinal injury. While his back had healed long ago the ache left behind kept him from being too active both in the field and the lab.


Rotor grumbled before turning back to the computer and pulling up a graph reporting instances of low fertility and low virility onto his timeline. The indigo hued walrus frowned as declining birth rates mapped to the increasing case of Mobians finding it hard or impossible to conceive. “... how long were you reading over my shoulder?”


“Uh about a minute and a half.” Tails replied as Rotor steadfastly avoided looking directly at the fox. 


Rotor let out a deep deep sigh as he was once again shown up by the fox. It was at once humbling and infuriating to him that the fox he had taught to read and write now regularly out did him in feats of scientific understanding. Rotor was usually able to salvage his pride by assuring himself that was a sign of good tutelage, at the moment though he was tired, hungry, thirsty, pained and frustrated. “I have been reading these reports for the last three days trying to make heads or tails of them and you just look at them for two minutes and you-!!!” Rotor’s rant was cut off by the hiss of a hypodermic injector.


---


Rotor stirred slowly pushing himself into a sitting position. The walrus groaned and pressed the side of his neck where he could just feel the mark left behind. His rather involuntary nap had done wonders for him. his eyes were no longer burning, his back didn’t hurt from sitting so long and his general desire to crush things with his bare hands had vanished. Glancing around Rotor found that the bed he was resting on sat next to a raised stand with a plated sandwich and chips with a drink and a note. Finding his glasses on the table as well he put them on before looking over the note.


“Rotor sorry about the tranq, Nicole warned me you were overworking and it looks like she was right. Enjoy a meal while I get some work done.” the walrus read as he devoured the offering. Rotor would be more offended that his friend and student felt the need to tranquilize him if he hadn’t been seconds from strangling the fox. As he drank one of the cans of soda Rotor realized that he was in fact still in the lab. Sound baffling walls had been set up in the seldom used south-east corner where he tended to pile whatever he needed tucked out of the way for his ongoing experiments.  The fact that proper walls, lighting and furniture had been set up in the lab while he was out was unsettling. Collecting the second can he walked toward the door which slid silently into the wall with a light push to the side. 


Sitting at the room's main terminal with one of the centrifuges was the unmistakable silhouette of Tails. Rotor silently crossed the dark room looking curiously at the tray of blood samples and testing equipment. Looking over the fox’s shoulder to the screen Rotor realized the fox was tracking some sort of biological vector. 


“Please tell me we don’t have a plague on our hands.” Rotor pleaded and laughed at the fox nearly flying out of the seat.

“Ouu! Okay, I deserved that.” The fox said, swinging the chair around and giving Rotor a cause to rub his eyes and double check the environment. “It’s not a plague if anything this data shows a gigantic improvement in the health of the afflicted.  Before you ask, yes those are my real boobs. If you want I can show off more of the change.” Tails gestured back at the screen. “I’ve been able to confirm that this dramatic change is caused by a virus that passes via bodily fluid and seems like it could be carried in the blood.”

“So Sexual transmission would be its primary vector. I can assume you are patient zero?” Rotor said, looking around for his spare chair and walking over to retrieve it. As he wheeled the chair into  place it occurred to him the whole lab was spotless and that his haphazard piles of notes were gone, spotting a  new row of filing cabinets he figured out where they must have gone. “Describe the most notable effects of infection.” Rotor said, sitting down and pushing Tails away from the computer.

“Rapid tissue development, hormonal shift, development of opposite genders genitals.” Tails counted off. “By the way, I'm more like patient two.”

“Like?” Rotor inquired while also calling out his pupils' use of indeterminate language.

“Patient zero is either the Alternate Reality Tails who first gave the Futa virus to Sonic or it’s Sonic himself.” Tails replied. “Secondary changes include shifting gender identity, improved health, heightened sex drive.”


“You had sex with Sonic?” Rotor tried to keep the jealousy out of his voice but couldn’t.


“Also Ray, Mighty, Cosmo, Barby  and Zooey who is now my girlfriend!” Tails announced with a smile and a barely visible tent in her dress. “I’ve personally started identifying as a vixen cause according to Sonic Futa’s determine gender by whether they fuck or get fucked more often.” Rotor was stunned and his emotions were so mixed he didn’t even know how to process that revelation.  “Sonic said he had sex with Ash and Mina and of course me, I think he said he was gonna hook up with Amy.”


Rotor took a drink of the soda, setting it aside as he tried to process his bafflement. Rotor's brain latched onto something, a singular solid point in his present sea of confusion. “You reorganized my lab.” It wasn't a particularly helpful statement but it served as solid ground. 


“Oh yeah it was a mess in here. Actually that might be a minor side effect of becoming a Futa cause like the day after i changed I was looking at my house and went on a cleaning spree! Redecorated everything inside and out. I had to clean up before I got to work.” Tails declared cheerily.


Rotor blinked absentmindedly, grabbing what he thought was his soda from earlier off the table and slugging it back. “H-how long was I out?” 


“Most of the last sixteen hours.” Tails replied before spotting the can in Rotor’s hand looking back at the table. “Uh i think you just drank after me.”


Rotor looked at the can in his hand and realized that it was a root beer and not the cola he had thought. “One of these days i’m going to drink something really dangerous like that.” he remarked before tapping on the console getting Nicole's attention. A winking Icon indicated the Hololynx was listening. “Nicole prep a bio scan on me to document the effects of a transformative virus.

“Oh that’s the second time in the past few days someone has brought up a transformative virus.” Nicole said.

Rotor blinked at the screen. “Uh huh, who else do we know that got afflicted by the Futa Virus.” 


“Charmy, Espio, Vetor and Jewel.” Nicole read off appending them to the tree. 


Rotor gasped as his changes started. It began from the Walrus’s belly and rolled out across his body like a stone dropped into water. His perpetually pudgy gut tightened up he slimmed down as that fat shoved down onto his hips and up onto his chest where it formed into truly impressive breasts. Rotor marvelled as the fat seemed to melt off his arms and legs giving him a curvaceous and toned body. He felt more than saw his face changing, his features rounding. He grew long locks that framed his face in indigo. Rotor was so enamored with the soft hair that he missed his hips shifting wider and the slit that formed between his thighs, at least until his belt gave out. Rotor took a few deep breaths, hands gently rolling over his features. A ping from the computer drew his attention away before he could get seriously into feeling himself up. 

“The health benefits of this transformation are remarkable.” Nicole added as she processed the data for Rotor. “Not only did it heal your spinal injury, it’s as if that injury never happened.” 


Rotor noded. “I feel amazing!” The walrus turned to the vixen. “Get naked, I need to test something. Nicole camera’s off, this is a private matter.”


Tails grinned, slipping her dress off with a practice flick. “You gotta know how it feels right?”


Rotor gave no reply, simply grabbing the nude vixen's half hard cock and stroking it until it was firm and throbbing in his hand. It wasn’t anything that he talked about Rotor was distinctly more a fan of cocks than he was of pussies or tits though he was going to be coming around on that soon enough. The difference in size between the two Futa’s was such that in order to Mount the Vixen all Rotor had to do was take a couple steps forward guiding Tail’s cock to her eager pussy. The walrus moaned as not only was his new sex very sensitive but Tails was better equipped than just about anyone he had been with before. Tails was quick to get with the program, taking hold of Rotor's thighs and pushing up into the walruses sex, balancing on the tips of her toes to drive as deep as possible into Rotor. Tails hadn’t come here looking for sex but she hadn’t said no to an offer from anyone she knew and probably never would. Rotor groaned in delight as his pussy was stuffed to the brim, the vixen’s member helping him discover the depths of his sex and all the hidden pleasure spots within. Rotor’s cock standing stiff and proud found itself fairly naturally between Tails Breasts, the soft warm orbs sliding up and down his shaft giving the walrus a tit job almost totally by accident. Not that Tails minded even slightly, in fact the sight of her mentor's cock sliding in and out of her cleavage inspired her to lean down and add to his pleasure by sucking on the tip of his cock. Rotor was discovering the joy of playing with his own breasts, delighting in how sensitive his wide round nipples were and how delightfully malleable the flesh was. Finally it was too much for either of them. Tails gulped down the cum that Rotor’s cock offered up aplenty, as her cock was milked into surrender by the Walrus. Rotor gave a huff of purest delight as he felt Tails’ cum filling his newly formed womb.


Rotor stepped back feeling the cum drip down the inside of his thigh feeling clearer headed than he had in months. In truth he had been neglecting his needs in a lot of ways. “Ooh that’s way over due.”

“You're telling me.” the vixen said wiping cum from her mouth and breasts, Rotor hadn’t been done cumming when he backed away. “Okay so I'm gonna leave the rest of the testing to you.” Tails paused to lick her hand clean. “Go home and come back with some clothes for your new figure.”

Rotor nodded and then looked past Tails to where his new lab-bed was. “I’m going back to sleep. I need way more sleep before I can get anything productive done.” Tails nodded and collected her dress from the floor as Rotor headed to bed.


---

Rotor groaned as he got up that bed was much nicer than falling asleep in his office chair but he had over exerted himself. Rotor found a smile coming to his lips as his body swayed of its own accord. He blinked when he found the lab lights outside his new bedroom on.  The blood samples were gone from the desk and a note was stuck to the nearby freezer. 

“Hey bossman, collected the blood donations and sent them off like you asked. Signed Dave.”  Rotor looked from the note to the tray where the Futa infected blood had been. 


“Uh oh.”