Eternal Tuat (Sekhmet's Guardians #4)
V.S. Nelson

Bagsu, his name alone strikes fear in the Guardian Nation.
What can cause one twin, destined to take his father’s place as a priest turn evil and lead a crusade to dominate the human race while the other fights to save mankind?
Finally, secrets are revealed when Bagsu leads us back in time to the land of New Tuat. Experience first hand what really happened to Bagsu and Gabriel long before they became immortal, when twin brothers were the best of friends.