Black Blades — Ginn Hale

Volume Three. Once Kahlil had been entrusted with a holy duty: to watch
over the Rifter and protect him in the world of Nayeshi until the
Issusha'im Oracles decided whether to summon the destroyer
god or kill him while he remained a mortal in Nayeshi. But
Kahlil failed his duty, slipping away to rescue his sister from
a fire and in that moment allowing the Rifter to cross into the
world of Basawar.
Desperate, Kahlil followed the Rifter. But the Great Gate had
been shattered, and Kahlil suffered catastrophic injuries to both
his body and his mind during the crossing between worlds.
He has returned to Basawar, but his home is not as he remembered
it -- inasmuchas he can remember anything. With all signs
of the holy sect he once served now wiped away, there is no one to
remind him of his purpose. In his wrecked condition he accepts the
only help offered and takes work in the noble Bousim household as
a spy and an assassin for handsome Captain Alidas'ro'Bousim who
patrols the seething underbelly of the capital city of Nurjima.
Now, after two years of faithful service, Alidas sends him on
a final mission: to infiltrate the Lisam household and stop Ourath
Lisam and his circle of noble conspirators from assassinating the
Fai'daum leader, Jath'ibaye.