Over My Head — Charles de Lint

Life is complicated in the once-quiet beach town of Santa Feliz. Over the past six months many teens have inexplicably become animal shape-shifters known as Wildlings. The town is rife with fear, and Wildlings have quickly learned to keep their animal identities hidden or face persecution.

Now that Josh Saunders has a mountain lion living under his skin, his life seems to careen from one crisis to another. His best friends have just helped him narrowly escape cruel medical experimentation, and now that he's back home Josh wants at least a few more days of living like a normal teenager. But the FBI is tailing him, a vengeful school bully is out to hurt and expose him, and a formidable Wildling Elder has secretly arranged to have him killed by the hand of one of his own Wildling friends.

In Charles de Lint's dramatic follow-up novel to Under My Skin, Josh must confront all the inherent dangers of his new life, including violent street gangs and the threat of treachery on the part of some his very best friends. His longtime confidante, Marina, is once again keeping secrets from him, and as Josh discovers how to harness and wield his newfound powers, he faces crucial decisions about the bonds of leadership, love and loyalty.