Slayer by Kiersten White From Goodreads: Into every generation a Slayer is born… Nina and her twin sister, Artemis, are far from normal. It’s hard to be when you grow up at the Watcher’s Academy, which is a bit different from your average boarding school. Here teens are trained as guides for Slayers—girls gifted with supernatural strength to fight the forces of darkness. But while Nina’s mother is a prominent member of the Watcher’s Council, Nina has never embraced the violent Watcher lifestyle. Instead she follows her instincts to heal, carving out a place for herself as the school medic. Until the day Nina’s life changes forever. Thanks to Buffy, the…