Renegades Magic
by Robin Hobb
The story begins with Nevare Burvelle scheduled for execution. However, Burvelle has been framed, and manages to escape with the help of his former lover, Lisana. The Gernia people (Nevare's ethnic peoples) plan to cut down a forest full of Elder Trees, which house the spirits of the ancestors of the Speck people. Soldier's Boy, a Speck spirit, inhabits Nevare's body and takes full control. Much of the novel is told from Nevare's perspective trapped behind this larger personality.
Nevare embarks on his attempt to undermine the effort to build the road, often horrified by what his alter ego is doing with his body, even though he is powerless to stop it. The Specks and Gernia come to a peaceful solution at novel's end, with Nevare ultimately accepting his abilities and personality.