In the last seconds before they both peaked, Ty wished for what he'd always desired getting to do with Eileen. It probably would've happened even without his wish considering they were fucking without any protection or hesitation, but his wish made it a certainty. He wished Eileen would get pregnant.
To make sure it wouldn't be too hard on her, he also wished for a few abnormal things to happen with her pregnancy- it would only take nine hours and not nine months for her to give birth, it would be totally painless, and she would be able to make the child age to adulthood and leave her if she wasn't comfortable with looking after it.
Once he felt the wish taking hold, Ty shamelessly allowed himself to come groaning to his climax. He hunched over Eileen like an animal marking its territory, his cock moving as deep inside her as possible, and semen began spurting from his tip like lava erupting from a volcano.
Ty's satisfaction was indescribable, and was heightened further when he felt Eileen's orgasm take hold, her passage clenching and milking him while her body shook under his own and she moaned and panted into his ear. They lay entwined at their crotches as the high slowly subsided, Ty's mind congratulating him. I managed to inseminate her, he realized ecstatically. I have reproduced.
Sure enough, he saw a vision of his sperm eagerly surrounding an egg inside Eileen and wear away at its walls, all desperate to fertilize it. He witnessed the egg capitulating and one sperm moving inside it to fertilize it before any others could, at which point it moved to implant into Eileen's womb. The young woman was pregnant a decade younger than she'd been when she had had Becca.