The Saga of Darren Shan ~ by Darren Shan
A series comprising four trilogies, The Saga of Darren Shan, started off as a side project, to keep Darren Shan, the author busy, while he was in between writing two adult books. The first book, Cirque du Freak, received such good reviews, that it metamorphosed into a series of 12 books, about a young boy, who is forced by a vampire to become his assistant.