Devil May Cry by Sherrilyn Kenyon

For millennia, the ex-god turned Dark-Hunter Sin has sought to regain his powers and take revenge on Artemis. But now he has bigger fish?or in this case, demons?to fry. The lethal gallu that were buried by his pantheon are stirring, and they are hungry for human flesh. Their goal: To destroy mankind. Sin is the only one who can stop them…if a certain woman doesn't kill him first.

Enemies have always made strange bedfellows, but never more so than when the fate of the world hangs in the balance. Now a man who only knows betrayal must trust the one person most likely to hand him to the demons. Artemis may have stolen his godhood, but this one has stolen his heart. The only question is: Will she keep it…or feed it to those who want him dead?