Does anyone think that Snape is a possibility? We don't know much about his history as of yet, and JK has said that she will reveal more in the next two books, so he could easily be half-blood. As far as the "prince" bit goes, the only two characters who possess any sort of royal status in the books are Voldemort and Dumbledore, so it would make sense that the prince would be a child of one of them. Snape has black hair like Tom Riddle and was once a Death Eater, so he could easily be related to (maybe even a son of--the ages work) Voldemort. He also has a hooked nose like Dumbledore, and Dumbledore trusts him for some mysterious reason, so the realation there is a possibility, though I find this more doubtful than the first theory.