Derrick's only recent memories faded again, this time dulling as he was regressed to birth, then pre-birth, and drifted in darkness for a while before heartbeats began to sound. One loud and strong, the others faint, but getting stronger as time passed. Nothing responded at first, but as more time passed, he got the feeling of having limbs. They were pressed again his body, and against another form that also grew. Memories, vague at first, but getting stronger, began to surface. The woman, Hebe. She had said she might make him unborn, to make him something else.
Even so, birth came as a surprise, fallout into bright light after being squeezed out of a place he had been for a long time. Along with another. He struggled to four legs, having difficulty finding the strength, but needing to get up to... nurse. Another form stumbled to join him at a cow's udder. And as the days passed, he remembered Hebe saying something about him ending up a Highland bull. His sister was probably another former guest from Hebe, though he had to wonder if it was a former male.
Time passed quickly, though he had no idea if he was in the distant past, the present, or some other time selected by Hebe. He started eating grass and hay, liking his vague existence of eating and sleeping, wandering the pasture, and the growing sense of mass and maleness. There had been two periods of cold before he began to notice a different smell from some of the females. And they started moving closer. Finally, one faced away from him and lifted her tail - and Derrick discovered the pleasures of being a bull.
That experience led to many more, and Derrick got used to being a popular male. His life centered between his hind legs, and he was happy for quite a while. Until he woke up in the middle of the pasture, naked and mostly human. He sat up, confused, then stared at the impressive bull's cock and balls between his legs. Maybe 15 again, but when and where?