The Isle of Glass - The Hound and the Falcon, #1

Alfred of St. Ruan's has lived his life in the seclusion of the monastery. But a badly wounded knight on a mission from the Elvenking, a beautiful and mysterious stranger who walks as both woman and beast, and a warrior king call him out of the cloister's walls into the wars and storms of the world. For he is neither mortal nor human, though he has long tried to live as both; and he can deny neither his nature nor his powerful magic.
Winner of the Crawford Award, and Locus Award finalist for Best First Novel.