Derricked blinked. "You mean I can go home?"
His father looked frustrated. "Not like that! You need to change back to how you were before! Human!"
Shaking his head, Derrick looked at the woman. "Not back where they came from. I mean HOME. The stables. I want to go back to my centaur."
"Are you sure?" The woman smiled, ignoring sputtering protests from his father. "If you go back this will most likely become permanent. You have almost fully changed physically, and it sounds like your mind is adapting just as fast. You will be a servant, possibly a kind of pet, but always subservient and little more than a useful animal."
That made Derrick frown. "I know I have been changed a lot, and wanting to be a slave to a centaur is probably really weird. But I have been truly happy for the past two weeks - no worries, no cares. Total contentment with myself and the world. If the price is being a servant, then I am happy to pay it. It doesn't feel like being a slave. It just feels like I have a purpose."
The woman nodded. "Very well. You may stay." She turned to his father, who was just starting to demand... something? He looked at the curious horse-human and the woman, and then around the room. "Um, sorry. I must have gotten turned around. My wife and daughter and I are just leaving. It was amazing! And winning the lottery here was fantastic! You can bet we will be making use of the free visits!"
He left, and the woman turned back to Derrick. "Your life has been rewritten. Your former parents only have one child, and no one will remember Derrick the boy. Return to your centaur. He will be most pleased to see you."
Derrick nearly galloped back to the stables, and gave his master a hug before settling into the routine again.