Now, in order to spend months and years on writing a novel, and to endure countless revisions, rewrites and proofreadings, you have to be a bit obsessive. It's easy to lose your patience unless you're determined to finish the job. (And you don't always succeed -- I've got many unfinished novels in store!)
How about obsession among readers, then? How much should a reader focus on a novel, or a series of novels, before her friends ought to get worried?
It's not just a question of "How many times can you read the same book before you get bored." The really obsessive fans are not satisfied with passively reading their favorite author's releases. They start writing fan fiction, they organize fan conventions, dress up as their favorite fictional characters... it gets cultish, and I've always found cultish behavior a bit disturbing.
If no one gets harmed by obsessive fans I suppose it's nothing to worry about. Still, I'm moderately itching to cry "Get a life!" when I read The Guardian's account of the Lumos 2006 "Harry Potter symposium" in Las Vegas:
"So, I say to the two women next to me, why are you here? Although in truth I think I already know: such-wonderfulbooks, JK Rowling-a-genius etc.
'It's just great to be able to talk to other people about Harry Potter,' says the first one, Lisa. I nod my head earnestly. 'Particularly,' she says, 'Harry Potter porn.'
Harry Potter porn? I say.'Harry Potter gay porn,' she corrects me."
From "Harry Potter and the mystery of an academic obsession", Carole Cadwalladr & Emily Stokes for The Guardian, August 6, 2006.
This wasn't at all what J.K. Rowling intended, but I fear she has no say in this matter. Once a book gets that popular, the fans think of it as "theirs" -- not in the legal sense, but in the obsessive sense. You haven't made it as a writer until somebody fanfics your characters.
And note how the fans call it "Harry Potter" fanfiction -- not "J.K. Rowling" fanfiction. To the most hardcore fans, the fictional characters apparently become more real than the author. Isn't that weird?