Half Wild (The Half Bad Trilogy, Bk. 2)

In a modern-day England where two warring factions of witches live amongst humans, seventeen-year-old Nathan is an abomination, the illegitimate son of the world's most powerful and violent witch. Nathan is hunted from all sides: nowhere is safe and no one can be trusted. Now, Nathan has come into his own unique magical Gift, and he's on the run--but the Hunters are close behind, and they will stop at nothing until they have captured Nathan and destroyed his father.