Covet - J. R. Ward

Redemption isn't a word Jim Heron knows much about - his specialty is revenge and, to him, sin is all relative. But everything changes when he becomes a fallen angel and is charged with saving the souls of seven people from the seven deadly sins. And failure is not an option.

Vin Di Pietro long ago gave himself up to his business - until fate intervenes in the form of a tough-talking, Harley-riding, self-professed saviour, and a woman who makes him question his destiny. With an ancient evil ready to claim him, Vin has to work with a fallen angel not only to win his beloved over...but to redeem his very soul.