Let the Right One In (2008)
Oskar is a bullied 12 year-old boy, longing to extract revenge on his tormentors but unable to build the courage to do it himself. But then he meets a girl called Eli, who gives him the strength he's been looking for. But Eli is not all she seems to be... based on novel or book, vampire, sweden, bullying, castration, bully, child vampire, murder, androgyny, new neighbor, nostalgic, young love, romantic
ETC.
