I was to be the perfect heir, to marry a woman and produce my own children. When I wouldn't spend my entire life lying to myself and miserable, he tried to do a ritual to-- to change me. [Of course, you don't get blood magic and all.]
Had it gone wrong, I would've ended up a drooling vegetable for the rest of my life, as much as it could've been considered one. Much better than having a son who only wanted the company of men, I suppose.