Ty awoke a couple of hours later, with Eileen still in his arms. He kissed her cheek softly and she murmured as she awoke. "Have you recovered now?" Ty asked.
"Yeah," Eileen smiled. She kissed him passionately, and within seconds he was back at full mast. "Looks like you are too. So, does my little changer have any more kinky ideas? Or does he just want to fuck a cute girl his age?"
Ty thought for a moment, and then smiled evilly. "I've got a kinky idea, thinking about it," he grinned.
"Oh?" Eileen replied.
"I keep on regressing you, but if you say it feels so good... I wanna try it too!"
"I dunno if you'd like turning into a baby!" laughed Eileen.
Pushing her down and giggling in reply, Ty pointed out, "Yeah, but you know, if you go back far enough... you get to a point where sex is all you can think of."
"Wait, do you mean..." Eileen asked.
"Yeah," purred Ty. "I wanna turn us into a sperm and egg."
"Oh f-fuck," Eileen moaned as Ty's cock pushed between her pussy lips again.
Ty pounded her fast, his balls slapping against her. He could feel both of their bodies aching to de-develop and combine with each other. "I wanna fertilize you, Eileen," he panted.
"Fuck yeah," Eileen whimpered in reply.
"I want my body to be yours, and your body to be mine!" Ty groaned. Soon, he felt his cock twitch and Eileen's pussy clench as he came inside her, and he wished for them to regress. Their bodies shrank and shrank, his body seeming to melt into hers and hers into his, until Ty was a sperm touching Eileen's ovum body, and he pushed into her body, fertilizing her.
The xygote that had been Ty and Eileen wished itself into a womb to grow, and instantly found itself there. Ty's consciousness quickly came to life in the egg, and a moment later, it felt Eileen's was there too. "Oh wow," Eileen said in their minds. "We're... we're one person now!" A moment later, she added in a mischievous tone, "...and I can feel something weird. I have your powers too now!"