My Sister the Vampire: Switched by Sienna Mercer (author) (UK edition)

Olivia Abbott is a cheerleader – pretty clothes, pretty hair and pretty perfect. Ivy Vega is definitely not the cheerleading type – black clothes, black eyeliner, pale skin. They’re as different as day and night – except that they’re twins! When the long-lost sisters meet for the first time, Olivia discovers that Ivy has some skeletons in her closet. But that won’t stop them from getting to know each other’s worlds. After all, blood is thicker than water – and much tastier too! A killer comic tale of schools, sisters and secrets for young readers to sink their teeth into.