Obsidian: Awakening by Sienna Frost

An epic tale of humanity that survives its ugliest and most admirable moments, one that will change your perception on love, life, and what it means to be human forever. When Hasheem, a legendary male-escort-turned-assassin finally escapes the city that enslaved him as a child, he finds himself trapped in the centuries-long war between his nomadic race of desert warriors and an empire that seeks to rule them. There, a new set of shackles awaits him in the form of a fifteen-year-old girl and her oracle brother whose agenda plunges him into the blood sport of power and politics. As warfare exacts its price and the line between good and evil gets put to the test, the men and women from both sides are forced to fight a common enemy that remains the greatest threat to mankind: humanity and all its flaws.