The act June and Dusty prepared to perform would have been abhorrent in their old bodies. But Ty's wish had made them into different people, literally and figuratively, and all they could focus on was how much they needed to fulfil their bodies' instinctive, insatiable desire to mate.
June pushed his hips forward, and his cock spread Dusty's pussy lips, making them part and allow him inside her. Dusty moaned eagerly as the intense emptiness inside her was relieved by having a penis fill her up, while June panted in response to how warm and tight her inner walls were around him. He slid inside her until he got down to the balls, and they kissed eagerly, June cupping Dusty's soft boobs to comfort her as she got used to the sensation of having a cock inside her.
June leaned forward and purred into Dusty's ear, "Now I'm gonna fuck you, and I won't stop fucking you until I knock you up with my cum like I did to Ty and Mark."
Dusty had barely had time to process what he had said when June slowly pulled his hips back, all but his cock head withdrawing from her and making her ache inside- and then he thrust back in, his balls slapping her crotch and his head brushing along sensitive spots deep inside her, and she moaned inarticulately in amazement at the sensation.
June established a rhythm of thrusting like that, and Dusty moaned and shivered and shook under her, barely able to process the unreal feminine pleasure she was getting. She felt like she could barely control her body, but it felt so amazing that relinquishing control felt right as her breasts bounced and her pussy clenched and her nipples and clitoris throbbed in response to the pleasure June was giving her.
Meanwhile, as he watched Dusty losing her mind with arousal under him, June felt his own pleasure surge higher and higher and his peak draw near. Once he could tell he would soon cum, he hunched over Dusty on all fours like an animal marking its territory, relinquished control of his hip thrusts and rode out his peak with a kind of satisfaction he'd never felt from womanhood. Knowing his seed would claim another's body and make them bear his child was intoxicating, he wished he could turn every male to a female and do this to them!
With a deep groan and a girlish moan, June and Dusty came in perfect sync. He pressed his whole length inside her and his balls twitched against her as he pumped her full of warm semen, and she quaked around him as her mind went blank with pleasure and she orgasmed around his ejaculating manhood.
June slowly withdrew himself from Dusty, and slowly her eyes opened and she saw their post-coital bodies. Peering over the soft soft breasts on her chest, seeing June's shaft covered with their combined juices and feeling some of his excess cum ooze out of her pussy, Dusty had to accept what had happened- she was not a boy anymore, and had never been nor would ever be a man. Now she was a woman.
Just to confirm this, inside Dusty's still freshly formed womb, June's virile seed tracked down her egg and set about working to leave their mark on it. Eventually one broke inside it and managed to fertilize it, with the newformed zygote implanting into Dustin and getting her pregnant.