Mike's equine parts had already made the decision, for his cock was already hard again, arching under his belly. Between the memories of the previous mating and the raging need that was already building up again, the centaur had little chance of resisting. He gave in to that need, and curiosity that might also be part of the growing instinctive needs of a stallion.
Moving beside the mare, he took more time to rub against her and drink in her scent. She nickered and dropped her head, swaying slightly. Her vagina clenched tight, then loosened, and she raised her tail to urinate. The pee scent carried additional odors that stoked the fire in his loins even higher.
Mike was vaguely aware of movement from the main pasture, but ignored both it and the shouts as he exercised his stallion's parts for a second time. As before, the entire mating process took less than a minute, yet he felt tremendous pleasure and satisfaction when he shuddered in release. It took longer for thoughts to clear, and he saw Brian and the local boy - Dar? - watching him. Dar looked amused, while Brian was frowning and saying something.
"...almost all horse now! What are you going to do? We need a centaur fighter!"
Mike understood the words, but when he roused himself to reply he could not quite remember how to make the sounds. He blinked wide-set horse's eyes, his protruding muzzle working in agitation. Moving to the edge of the pond again, he saw that he was far more horse now, the upper human chest collapsing into a shape more like that of an equine neck under a head that was much to large and misshapen to be human.
The reflection upset him - he did not want to be this ugly creature!