Matthew Sawyer's Pazuzu Trilogy - quick synopsis -
Alien gods have usurped an unguarded world. Pazuzu then awakes and this demon wants the wasted dominion for himself. But the alien gods and their monsters are everywhere. The demon needs a place to hide. Pazuzu finds Benedict Gage. The man wanders the waste alone and empty. Ben suffers amnesia. Nonetheless, Pazuzu needs his help and a body.
Manifestation - The first book in the Pazuzu Trilogy.
Emergence - The second book in the Pazuzu Trilogy.
Abeyance - The last book in the Pazuzu Trilogy.