I am a twenty-something who fell in love with all things Harry Potter in high school and never grew out of it. The books are the best, but I love every single one of the films.
I prefer to stick to the canon-compliant fics, but occasionally I will wander into an AU. My favorites are Post-Hogwarts and Dark/Angsty. I never considered myself a shipper, but again, I go canon-compliant here. My favorite couple would definitely have to be Remus/Tonks, though. My favorite characters are, obviously, Lupin and Tonks because they're cool as hell, but I'm also a big fan of Dumbledore and his seemingly endless wisdom, Harry, Hermione, Ron (you've got to love the trio), Ginny, Sirius, and Severus Snape and his seemingly endless, witty cynicism. The Weasley twins are up there as well just because they're brilliant and they make me laugh.