Deviant Soul by Charity Parkerson (epub) Damaged Devils Book 2
He was trained to kill. In the process, he lost his sanity and his soul. Onyx doesn’t see any of that when he looks at Seven.
Seven is one of countless boys who trained through an underground program to follow the worst of orders. He broke free a long time ago. Now he uses his skills on his terms, but his sanity can’t be recovered. No one knows him. He’s simply a shadow. A nightmare. Except there’s this one guy he can’t shake.
The way Seven slips in and out of his life drives Onyx crazy. He wants to hate him. Seven is too hard to resist. Just when he thinks he’s finally made some headway towards a real relationship, Seven’s secrets come crashing down on them. Now Onyx has a choice to make. He can believe the worst or follow his heart. Either way seems equally doomed.