"What I want is to be her foal." Mike chuckled. "But since that's not possible..."
"Oh, but it is!" interrupted Liam. "And you will be a wonderful foal! Let's get you ready."
Mike was sure this was some kind of joke - how could he be a foal? Then again, he had been made into a centaur - it just meant him being younger.
The stableboy led him into the mare's stall, and Mike felt himself responding to her scent. She was in heat and very interested in his stallion's parts. He shuddered as a wave of lust passed through him - Liam must have misunderstood him, but mounting the mare was what he not only wanted now, but had to do. After a couple of awkward bumps, Mike pushed over the filly's rump. Liam helped guide his massive shaft into the filly's slick opening, and he drove in hard and deep. The first release came after just a few thrusts, yet Mike did not pull out. instead, he continued the pounding, unaware that his upper body was changing, his equine body getting smaller. Arms dwindled, and his human chest condensed into the neck of a horse, supporting what quickly finished up into the head of a young Shire stallion.
Mike was dazed, the sexual experience incredibly intense. Liam patted his rump and grinned. "Simple transformation is usually reversible, but rebirth changes your basic soul. You will be a horse forevermore, no matter what other magic is used on you."
Rebirth? Mike was confused, unable to think clearly. It was very hard to stay on top of the mare now - he was much smaller, his hind legs starting to slip and even miss the ground. Yet he did not fall - his enormous cock was holding him in place, the filly milking him for seed.
"That's it. Let her prepare the way - you will be your own sire, restarting in her womb as her egg and your sperm join. Your place in the universe will be redefined, and when you emerge a year from now, you will be a true animal."
Mike was no longer thrusting, and twisted his equine head to see his entire form starting to grow slick and damp. He was turning into horse semen! Awareness dimmed, and just as the mature colt hanging off the Shire filly's rump dissolved into a huge mass of thick horse cum, his mind went blank.
The stableboy waited for the mare to calm down, then moved her to another stall so he could clean up the sticky mess. She was now pregnant with what would be a fine Shire foal. The former centaur might be a filly or a colt when he emerged, but in any case he would be a beast, a true animal. Liam was curious to see if Mike would remember any of his past.