Any fandom that started during one's impressionable youth will only deepen with age: Ergo, all the fortysomething dudes dressed as Stormtroopers at Comic Con. We're seeing that in full effect now, thirteen years after the first Harry Potter book was released. There's the self-proclaimed world's biggest Harry Potter fan and his movie-poster-papered room, the Harry Potter role-players at Grand Central Station, and the people stealing owls in India. But what about people like Glee's Darren Criss, who turned his enthusiasm into a charming musical? Or participants in the recent Quidditch World Cup? Are they just delightfully young at heart and impressively dedicated to their passions? Or creepily obsessed in a way that they should grow out of?