My favorite fan fiction of all time is 'Take My Heart Away' by Hatsu. It's Hermione/Tom Riddle, and it's incredible in character and refreshing. It's the only Dark/Angst fiction I've liked, and it made me cry. Go read it!
Summary: A series of poetry one-shots about Lycanthropy-specifically Remus's experiences with lycanthropy while still at school.
Summary: An artistic poem depicting when Harry was the snake in his dream and saw Mr. Weasley attacked.