I didn't have this problem with HP in particular, because it was one of my OBSESSIONS when i was younger, and when i'm really into a piece of media I just know everything and everyone in it. But i tend to have trouble remembering the names of characters or who is who in books that I'm less interested in and have lots of ppl in them. I think it's normal, dw. Like someone already recommended, you could write a cheat sheet to help you remember