Odalisque. Book One of The Percheron Saga

Captured by slave traders in the inhospitable desert, Lazar fought his way to freedom, earning the coveted position of Spur of Percheron. Charged with protecting his adopted city from enemies on both sides of its walls, he has led a charmed life as confidant to and protector of Zar Joreb for many years. But now Joreb is dead.