Half Bad by Sally Green
Nathan is the only living product of a White Witch and a Black Witch. With his mother dead and his father hunted for murder, Nathan is under scrutiny from everyone who is waiting to see if he will turn dark upon his seventeenth birthday. However, Nathan is imprisoned before his birthday, to keep him from coming into his powers. With a will that surprises even himself, Nathan manages to escape and sets out on a quest to meet his father, the only one who can give Nathan his powers. The first book is a trilogy, Half Bad shows a dark side of magic where only the strong can survive.