Musings.
I think Remus Lupin is the Half-Blood Prince. Any Facts to support this? Only that he's a half-blooded. Nothing esle. Just a flightly thought. I just wanted to post it just in case I was right. :P
A more evidence supported assumption: Petunia is a witch but is denying it and/or she's going to do something freaky with magic in the next two books. Evidence you say? Behold!
Barnes and Noble chat from 1999:
Will there be, or have there been, any "late blooming" students in the school who come into their magic potential as adults, rather than as children?
No, is the answer. In my books, magic almost always shows itself in a person before age 11; however, there is a character who does manage in desperate circumstances to do magic quite late in life, but that is very rare in the world I am writing about.
Edinburgh Book Festival:
Is Aunt Petunia a Squib?
Good question. No, she is not, but÷[Laughter]. No, she is not a Squib. She is a Muggle, but÷[Laughter]. You will have to read the other books. You might have got the impression that there is a little bit more to Aunt Petunia than meets the eye, and you will find out what it is. She is not a squib, although that is a very good guess. Oh, I am giving a lot away here. I am being shockingly indiscreet.
Hehehehe. What would Uncle Vernon say? *Insert evil laugh here* Serves her right for what she said about Lily.
PS: Harry Potter meetup guys: Who's all coming on Wendsday? I'd like to know ASAP. ^_^