Lower-middlebrows: Have read the books AND watched the movies. Deeply involved, and yet a bit confused. Don't remember too many details. Love Hermione, like they loved Dana Scully.
Middlebrows: Have pre-ordered the book. Have made plans to spend Friday night
Highbrows: Don't read Harry Potter. Claim that it is an insult to the fantasy genre. Wax eloquent about how it's a marketing gimmick, and how everyone has become a capitalist slave. In fact, they force the fact down everybody's throat that they don't endorse the franchise, or anything else. Visit the loo more than once during the movie.
*My guess: It's Sirius Black's Brother.