Inventing Elliot by Graham Gardner
After being bullied mercilessly, Elliot is determined to reinvent himself when he moves house with Mum and Dad and goes to a new school. He is going to be so cool that no one will touch him. He's going to stand out just enough not to get noticed.
But he is too successful, and he does get noticed by the Guardians. They are a mysterious group of three who manipulate others and run the school with a reign of terror. They invite Elliot to become one of them. He faces an agonising decision, whether to use this new found power or risk standing up for himself and facing the consequences.