As Daniel stared goggle-eyed at his masturbating sister, he gave a soft moan. Alexa's eyes flew open. She saw him standing in the doorway and her lips twisted with anger as she spoke. "What are you looking at Fag?"
"Fag??" said Daniel. "What??"
Alexa's eyes rolled back in her head and for a second she went limp. She got to her knees, rubbing her eyes. Daniel took off his robe and threw it over her, leaving himself in boxers.
"Daniel?" she murmured, holding onto his chest for support as he stood up, "What are you doing here? Is dinner ready?"
"Um, look Sis, you've been acting really weird today. Maybe you should take a shower and get some rest, instead of going on that date."
"Oh God, my date!" She picked up her phone. "Ryan will be here in half an hour! I have to get ready!" She ran into the bathroom and turned on the shower. Daniel shrugged and went back to his room. He took off his boxers and began slowly touching himself, trying to think of Elena Popescu instead of his sister. After a while he succeeded.
Alexa relaxed as the shower washed the sweat off her glowing body. No matter how much she lowered the temperature, she still felt warm. She walked back to her room and finished towelling off. Then she examined herself in the full length mirror on her closet door. Her skin was more tan than she remembered. And though she didn't go to the gym every day, she looked very fit. She flexed and wondered if she was becoming too muscular. Never mind, she thought. Then she looked down and wondered whether to trim her public hair. Being Asian, her pubes were naturally straight and lengthy. No, she decided. Let Ryan gag on them.
She put on lace panties and squeezed her legs into a pair of skinny jeans. She decided against wearing a bra and threw it next to the robe on the floor. Wait, she realized, that's Daniel's robe. Didn't he put it on me? Did he see me naked, with my fingers in my cunt? She smiled wickedly into the mirror as her hand slipped behind the waistband of her jeans. If he did, fuck him. Literally. Bend him over and fuck him. Her fingers were back at her clitoris, rubbing away. Yes, fuck Daniel, fuck Ryan too. Put my dick in him, make him moan like a bitch cause I'm bigger than he is. She thought of his muscles heaving while she plowed him, then thought of her own muscles flexing with every thrust.
She moaned like a bitch in heat, watching her reflection in the mirror as the moon rose, full and round like a buttock. She unbuttoned her jeans to give her hand more space. The moonlight covered her. "So strong" she dribbled, "So hot...burning up...ohhhh..." At first just her pussy felt aflame, but then the fire spread to her limbs. She writhed in the moonlight as her arms and legs stretched, along with her increasingly blocky hands and feet. When she straightened, she was a foot taller and skinnier. Her nipples had long been hard, but now the hardness spread to her jutting breasts. They quivered, and seemed to jutt a little less when they finished. The process repeated itself. Less and less pleasure emanated from her red-brown nipples, but she didn't care as long as her clitoris continued bulging behind her panties and in-between her fingers. It was pulsing and plumping like a balloon, sending her into a frenzy.
"Oh my fucking God!" she cried. Her voice broke as she fell to her knees in front of the moon. Now her entire body was pulsating as muscles throbbed and grew beefy to accommodate her stretched limbs. Behind her breasts pectorals puffed to dinner plate size, while her abdomen flexed into a six-pack. Biceps and triceps throbbed with each new layer of meat. Her shoulders broadened as her hips narrowed. Her thighs and calves pressed against the confines of her jeans, bursting several rows of seams. "Aaarrrrgggoohhhhhhhhhhh" groaned the no-longer feminine human in pleasure, as its voice plunged to a low, rumbling baritone.
Now the flames in its groin were licking away at its deepest cavities. Ovaries juddered as they mutated and pushed downward to the labia that rolled them into a sack of new skin, sealing the space where a vagina had once been. Inside the new jumbo-sized testicles sperm were spawning and buzzing. All the while the clitoris lengthened and lengthened like a snake uncoiling, veins cording the flesh-tube as it stretched from one inch to two, then doubled to four, then doubled again. Finally its tip mushroomed and a dark bulbous head peaked from the foreskin of the eight-and-a-half-inch penis.
Hair sprouted, shooting up from the forearms and thighs, curling upward into a dense pubic bush and then marching a swirly trail to the belly button, continuing in a line up the torso and clustering between the pectorals and now-imperceptible breasts. Rings of hair formed around the shrinking dark brown nipples. Only the long hair on the head retreated, halting past the ears. The contours of the chin, cheeks, and forehead hardened into chiseled, angular lines. Nostrils flared as the nose thickened across and outward. Stubble grew above and below the thinning lips. A lump protruded from the throat and refused to go away.
That marked the end of the transformation. A newborn man stood in place of a girl, his coarse hands wrapped around an intimidatingly thick penis. As he came for the first time, splashing thick ropes of semen into the air and against the window, he howled at the moon.