As well as knowing he was bi, there was something else Ty had realized about himself once he started puberty. Sometimes, he fantasized about being a girl. It wasn't that he didn't want to be a boy, but he felt like that wasn't all there was to his gender. Now he had this power, he wanted to experiment, and given the stuff he'd fantasized about was often kinda sexual, this was a perfect time.
"Hey, babe?" he said to his lover.
"Yeah?" the boy replied, still cleaning himself up from where Ty had shot a load into him.
"Um... if I was a girl, would you wanna fuck me?" Ty mumbled.
"Are you trying to get me back in the mood?" laughed the boy. "Definitely, I think you'd make a really hot girl."
"Thanks," Ty blushed, wishing the boy would be ready to fuck again. A split second later, he saw the boy's cock stand up erect again, and he looked at Ty with a pervy zeal.
To Ty's surprise, he felt the boy grab his hands, push him to the bed and rub his firm shaft along Ty's. "In fact," the boy purred, "why don't you do it now? You fucked me, now you should wish to turn into a girl so I can fuck you."
Smiling, Ty replied, "that's a really good idea."
"Then change yourself already, you big slut," teased the boy. "I wanna find out how good your pussy feels to fuck!"
Ty giggled and kissed him, and wished to turn into a girl. He panted as an odd warmth spread through his body, and he started to change. His facial features softened and his hair lengthened, while his body hair seemed to vanish almost everywhere else. His figure slimmed, his muscles turning more lithe as his hips widened and his butt rounded out, and a soft curve emerged in his formerly straight figure.
Ty moaned and the boy felt his cock almost pulse with arousal as the feminization of Ty's sex became apparent. His nipples suddenly felt extremely sensitive and perked up, and he breathed heavily as flesh quickly formed around them and they seemed to widen and lengthen. The changes finally shifted to his crotch, as his balls moved up inside him and the cock which minutes ago had filled his lover with cum receded into his body rapidly. Within Ty, his testicles were reshaping into ovaries and connecting to a vaginal tract and womb, while externally his scrotum tucked inwards and formed labial lips and the nub that remained of his penis shrank and accumulated more and more nerve endings in a tighter and tighter space as it formed a clitoris.
At last Ty felt his new slit open, and it clicked in her: she was not a man now. Right now, she was a woman, because she wanted to be. "Am I a hot boy?" she asked the boy in front of her.
"No," he giggled, kissing her passionately. "You're a really hot girl." Hearing that from him made her emasculation feel perfect, particularly when his hands cupped her boobs and rubbed against her sensitive nipples softly but firmly.
A moment later, he made it feel even better, as his cock head brushed against her clit. Ty almost moaned in surprise. "Can I fuck you?" the boy asked quietly.
"You'd better fuck me," Ty replied sultrily, and she felt the boy's hips piston his cock inside her. Oh fuck, this felt amazing! Having something inside her pussy was primally satisfying in a way she could hardly describe, kinda like fucking a hole with his cock but obviously the opposite. As it thrusted in and out of her rapidly, the feelings intensified, the thought of how she had made her body one that could take this making it even more satisfying.
The sensations of the boy fucking her felt just as amazing being on the receiving end: the loud slap of his hips against her and the feeling of his balls brushing against her pussy as he pounded her, his low-pitched grunts and her higher-pitched moaning, being able to feel every vein of the boy's cock rubbing along her pussy walls, and his cock head occasionally touching her intensely sensitive G-spot and pushing her to peaks of pleasure.
Soon the boy breathed sensually into Ty's ear, 'I'm gonna- I'm gonna-', and this was all it took to give Ty her first female orgasm. The knowledge he was about to cum inside her made Ty's slit tighten around the boy's shaft, wanting to eke as much seed as she could out of his cock just as his ass had made him, and the first touch of warm seed flowing deep inside her made her mind go blank. For a moment, every masculine feeling in Ty faded from existence, and she embraced the instinctive joy of her new womanhood, the knowledge that her body had been fertilized and impregnated as she desired so primally.
When she came down from the high, she felt the boy finally pull out of her, and grabbed his cheeks and leaned in to kiss him. They kissed passionately, and he said softly, 'You're fucking perfect, babe.'