Transformation by Carol Berg
Seyonne is a man waiting to die. He has been a slave for sixteen years and has lost everything of meaning to him:his dignity, the people and homeland he loves, and the Warden's power that enables him to step into a human soul and do battle with demons. But Prince Aleksander, heir to the Derzhi empire, has been possessed by the very demons that Seyonne once fought - demons now allied with the savage Khelid nation. Seyonne must recover his power and cast down the Demon Lords before they destroy both the Prince and his empire. Look out for more information on this book and others on the Orbit website at www.orbitbooks.co.uk