Blood Sinister by Celia Rees

“Ellen hasn't seen Andy for years - and the transformation is incredible. He's tall, with high cheekbones and tousled hair. If Ellen was normal, she'd have a massive crush on him. But Ellen is dying. Her illness is a mystery. It's as if all the strength is slowly being sucked from her. What dark force is reaching out to claim her, draining her lifeblood away? This is a dark, compelling vampire thriller from the author of "Witch Child"." (Summary from Amazon.com)

Paperback info: ISBN 1407115502, Scholastic, August 2009