One day, he befriends Eli, a girl of about the same age, who just moved in next door. She lives with an older man named Håkan, a former teacher who was fired when caught in possession of child pornography. She's revealed to be a vampire who was turned as a child and is therefore stuck forever in a young body and mind. Oskar and Eli develop a close relationship, and she helps him fight back against his tormentors. Throughout the book their relationship gradually becomes closer, and they reveal more of themselves, including fragments of Eli's human life. Among the details revealed is that Eli is a boy named Elias who was castrated when she was turned into a vampire over 200 years ago. However, she dresses in female clothing and is perceived by outsiders as a young girl.