The Sable Moon

Description for THE SABLE MOON by Nancy Springer:

Like a misty fog, a dark force rolls over the Isle of Welas. Now proud-hearted Prince Trevyn must embark on a quest to free the Isle of evil's grip and realize his own legendary destiny... - Prince Trevyn hates Gwern, the weird boy who suddenly turns up one day. He does not know why his parents Alan and Lysse take him into their castle. His hatred causes him to run away where he meets Wael for the first time, Wael is a god that inhabits the bodies of wolves and is attacking villages. Trevyn turns up in a village just in time to save Meg, a village girl whom he quickly falls in love with. Wael has other ideas as he lures Trevyn over the sea to Tokar where he is enslaved and sold to an old priest. It is here that Trevyn learns the true nature of Wael and escapes to try and use this information. He finds himself on Elwestrand, home of the elves, where he is reunited with his uncle and learns more of Wael. Once he returns to Isle he fights the wolves but it is not until Gwern is killed and hands his powers off to Trevyn that he finally has the power to defeat Wael and be re-united with Meg.

This is the third Book of The Isle.