Ty saw the fetus's sex characteristics start to develop, and they took a form akin to that which he had had. A sealed mound protruded from between its legs, and a thick shaft developed above it- the fetus was now clearly male. Ty decided to accelerate its life to a pubescent state so he could properly come (ahem) back into existence.
Before his eyes, the fetus grew to term, then was birthed, and rapidly aged years from an infant to a boy and then a young man, at which point Ty's form was reshaped by his pubescent changes. Ty felt himself form a body that was almost immeasurably miniscule, and a long tail extended out from him. He soon managed to use it to start to swim around inside the fluid he now lived in. Ty was now just a sperm inside his new host's testicles.
However, he did still have his power, and with that he wished to accelerate to the point at which he got conceived. He found himself watching a handsome man fucking a really pretty woman, his cock pounding into her with nothing separating his flesh from hers, faster and faster as they both approached their orgasms. Ty felt a twinge of anticipation as he prepared to get to impregnate the woman, making a quick wish he would be the sperm that fertilized her egg.
At last, he felt himself get released from the body of the man whose body had formed him, and was shot vigorously from his penis inside his lover's vagina. Ty swam and swam, drawn to the huge ovoid before him like a moth to a flame, and burrowing inside it hastily. He felt himself seem to merge with it, and their combined form settled inside the uterus of the woman they inhabited, impregnating her and allowing them to start to develop.
Ty wondered who the people who bore them were... (A/N: feel free to add more ideas, obviously!)