Starless / Jacqueline Carey.

Enhanced descriptions from Syndetics:

Jacqueline Carey is back with an amazing adventure not seen since her New York Times bestselling Kushiel's Legacy series . Lush and sensual, Starless introduces us to an epic world where exiled gods live among us, and a hero whose journey will resonate long after the last page is turned.

I was nine years old the first time I tried to kill a man...

Destined from birth to serve as protector of the princess Zariya, Khai is trained in the arts of killing and stealth by a warrior sect in the deep desert; yet there is one profound truth that has been withheld from him.

In the court of the Sun-Blessed, Khai must learn to navigate deadly intrigue and his own conflicted identity...but in the far reaches of the western seas, the dark god Miasmus is rising, intent on nothing less than wholesale destruction.

If Khai is to keep his soul's twin Zariya alive, their only hope lies with an unlikely crew of prophecy-seekers on a journey that will take them farther beneath the starless skies than anyone can imagine.