The house was still and quiet. The ticking of the large grandfather clock was the only steady sound in the place, with the occasional interruption of the air conditioner kicking on or the creaking, groaning sounds of old wood timbers settling ever deeper into their frame. Jessica tossed restlessly on the bed, her long brown hair damp and limp with sweat. Her dreams had slowly gotten more and more intense over the past few days, and her libido had grown more and more as well. Tyler had done all he could to keep her needs at bay, bringing in air purifiers that filtered the cloying smell from the air and getting her some fun dildos and plenty of lube, but even that hadn't kept him from succumbing to her need and fucking once more.
He had been locked in his room for the past day now, pouring over the samples and emailing anyone he could to help him figure out what was happening. He had told her that all the samples look like normal human skin cells to him and to everyone he had sent pictures too, even the parts that were "tattoo'd." They didn't even have signs of pigment, which mystified them both. He was trying to get a conference call scheduled with a mentor of his, but so far Dr. Mendez had been too busy to get in touch. Jess knew that hurt Tylers feelings a bit, but she was confident he would make it happen.
Deciding the sun in the sky would definitely keep her awake no matter how long she lay there and wished it away, Jess got up for a morning shower. The simple act of stripping her shirt off was enough to get her horney nowadays, the sheer fabric tugging at her erect nipples and making her think of Tyler's cock again. She padded barefoot through the hallway to the bathroom, and started running the water. While it heated she rummaged through the cupboards and grabbed a couple towels and draped them on a bar by the radiator to have them at hand. If it had been winter she would have warmed the towels up by putting them on the running radiator, but the heat of a full summer was already pressing into the house.
She soaked herself in the perfect temperature, letting the water run over her c cup breasts and pudgy stomach to stream between her legs and over her shaved smooth pussy before sheeting off her legs and onto the floor. The shampoo felt lovely and bubbly as she massaged it into her scalp, and the pulsing showerhead felt amazing on her back. Too bad it didn't have a removable wand or she might be able to put that pulsing to use somewhere it was really needed...
Taking only a few minutes, Jess stepped out feeling clean and ready to face the day. She shook her long hair out and wrapped it in a towel turban, but paused in front of the mirror before she wrapped her body towel up. She checked the tattoos every day now, tracing to see where they grew and how far. They had determined that they grew almost explosively after sex, inched along after masturbation, but did grow at a constant rate of about 3 inches a day otherwise. She turned and twisted, looking to see where the branches had reached while she slept.
It seemed odd, but none of the ones on her arms or legs seemed to have moved. Yes there was the mole she marked in her mind to trace the growth, and it hadn't come any closer. Hope bubbled briefly in her, and she looked carefully along every inch of her legs before turning and using a hand mirror to examine her back. There was growth there, and her heart sank again. A couple bundles of branches curled up the sides of her shoulders and traced up the back of her neck vanishing into her hair. Presumably it was working its way along her scalp as well, and wondered what that might mean. Could be anything really. But she needed to show Tyler.
Completely forgetting to wrap up in anything, she walked out of the bathroom and tapped on Tylers door. "One sec, sis." He called, and she heard his chair creak as he stood up. She suddenly realized how horny she was, imagining the way his dick must swing while he walked just ratcheted her to 11 and before he had even taken those six steps to the door Jess had decided that she didn't care how fast the branches grew, she wanted to fuck him. And as soon as he opened the door she pounced, falling on him and pushing them both to the floor. Tyler cried out in alarm at being knocked over, but the familiar prickling of the white flowers had him hard and wanting before he even hit the floor.
Jessica's scent was overpowering. The constant exposure to the venom and the smell made him more and more susceptible to its workings and he didn't even realize it. They landed on the floor, Jess pinning Tyler and ripping his shorts off before his brain could recover from the impact. By the time he knew what was happening Jess had pumped his cock twice to make sure he was hard and then mounted him, leaving him on his back pinned to the floor while her sweet pussy squeezed and massaged him. Tyler moaned in pleasure, his entire body convulsing in the need to fuck his little sister, to fill her with his cum.
