To the lab with Sunny and Z

Awaking with the still sleeping trio next to her in the late afternoon, Z assumed as sunlight had activated her transformation, the setting sun would take it away.

Rifling through Sunny's closet and drawers, she figured she should at least enjoy a few un-sex-crazed minutes of her hyper form. Z chose a half cup bra and crotchless panty from what Sunny had called her 'gonna sell stuff today' wardrobe. The garments presented as advertised, nipples out front, the hairless mons on center. She slipped on a silk shirt, blazer and dress pants.

As only mutant #4, however, the virus proved again to be unpredictable. She sat in an easy chair in the bedroom waiting for Zach to return. The last ray of light disappeared over the horizon and Z's form remained unchanged, while the threesome on the bed all sprouted forth their alien forms.

Only Sunny awoke and sat up. It seemed the morning's events still required more rest for Dani and Jenni, and they snored on, unaware of the hour or their biomorph.

"What do you think?", asked Z.

"I think we definitely need to take some samples and test this in the lab", replied a yawning Sunny, "and a Saturday evening would be perfect to draw as little attention to us as possible," with Sunny looking down at her two foot appendage dangling from the edge of the bed.

"My badge will still work, as long as the guard doesn't look at the picture", laughed Z.

Five years ago Zach and Sunny had spent a postdoc in the same lab, Sunny in pharmacology and Zach in genetics. The relationship started that distant summer, and today equipped them to dive deep into the analysis of their new predicament.

Sunny donned some of Zach's clothes, a sweatshirt and sweatpants, hoping to conceal as much of her form as possible. The nocturnal penis stuffed down one leg, swinging with every step, and E cup breasts almost spilling out the bottom band of the XL hoodie.

"Look at you", Sunny said, "you're the bombshell professional, and I'm going in the slacker boyfriend uniform."

Arriving at the complex and successfully gaining access to the lab, they took blood samples of each other and started the chromosomal analyses.

Each typical male karyotype had XY sexual chromosomes, denoted 46,XY. Similarly females had paired X sexual chromosomes, listed as 46,XX. Mutations known to medical science included single chromosomes like 45,X an triples such as 47,XXY and 47,XYY. Depending on the variant, the individual could live a normal life but the some also had unfortunate consequences.

Samples from Sunny yielded a sextet 50, XXXYYY, while Z's composition was a septet 51,XXXXYYY.

Staring at the screen Sunny gasped, "We've become new sexes, the fourth and fifth sex to be specific. Let's run some more tests."

Leaning over Sunny's shoulder, rubbing against her back, Z was both exhausted from the long night of analysis and aroused as she felt her nipples brush against Sunny though the silk shirt.

"I think I need a break", said Z, "can we clean this up and go home?"

Standing up, Sunny responded "Its 4AM and I've only got a few more hours of this", dropping her sweatpants. She walked past Z toward the door to lock it, her erection rising with each step. Striding back to Z, Sunny unzipped Z's fly and reached a finger into the moist vagina. Sunny only got one knuckle in before hitting the hidden cock. Encircling her hand around the flange, Sunny pulled the appendage out from its hiding and through the fly. Z gasped as her full two foot length squirted the rest of the way out, with much less exertion than the first time almost 24 hours ago.

Sunny stepped backward and aligned her fleshy pipe straight on, tip to tip with Z. This time Sunny's pheromones were dominating the duo, Z's eyes wide open but her consciousness under Sunny's command.

"Let's try this", Sunny said, as she pushed forward. Z docked into Sunny's urethral opening, Sunny's cock now encasing Z's until Z bottomed out. The duo thrust their hips back forth, fucking in the most futa like position. Nipples spurted and the unused labia swung and dripped during the mating frenzy. At last a stream of semen arose in Z's cock and upon its release traveled down Sunny's vas deferens, inflating her testes to dangling bowling balls.

True to previous form, Sunny passed out and slunk to the floor. The docking slipped apart with a loud, sloppy, sucking sounds. Z, however was now energized. Concentrating, she retracted her genetically modified gift back into her body and zipped her fly shut. Looking at her watch, it was 430AM and the June sunrise was right on time. Turining toward Sunny's prone figure, she watched Sunny's body change back to its "mostly" human shape, the virus gone dormant within.

"There's time for one more test before the cleaning crew arrives", Z thought to herself. "I need to see if our diurnal chromosomes are any different." She plunged a needle in her forearm and then next in Sunny's exposed thigh to draw blood. The results were astonishing... Z remained the mutated septet, while Sunny was now a normal 46,XX female. Sunny's mutation of the virus was kinetic, it shifted her chromosomes as part of each transformational episode. Z's were static and locked into a new alignment.

Sunny awoke, pulled her sweatpants back on, and stood. Still coming to, she watched as Z sterlized the equipment and then bleached the floor to leave no genetic trace of their visit.

"What did you find out?"