Oh, what an interesting idea! I couldn't stand Ginny in HBP, actually; the only thing that redeemed her in my eyes was that she was presented as a friend to Hermione and Luna, both of whom I like. But you're right that we never saw or heard her doing or saying anything genuinely friendly. She's a very aggressive, competitive and intolerant young girl, and I wasn't at all sure I liked her effect on Harry. One good thing I saw in the relationship was that she was able to stand up to him - but otherwise it didn't feel real to me.

However, she can't be a horcrux, can she? Voldemort wasn't actually there to do that to her; on the contrary, his horcrux was using her death to gain life. So what do you think happened to her?

I'd be very interested to know, because I love all your theories!