Body By Mage by F.N. Manning

To stop a killer, a mage and an incubus need to get closer magically… and sexually. But their hearts are off limits. Right?
Crime doesn’t pay. Not for Rob Walters. Being a petty criminal has only given him lots of enemies and a dwindling supply of magic, so he’s trying to turn his life around. But when the mage nearly resorts to his old dirty tricks during a moment of weakness, a gorgeous incubus catches him and gives him an offer he can’t refuse… a job offer.
When a deadly sex demon starts draining people dry and dropping bodies, Orion Lennox will do anything to stop the rogue predator who gives their kind a bad name. He’ll even team up with a loud-mouth mage who drives him crazy. The incubus assumes keeping things professional will be easy, but the growing magical and sexual connection between them is hard to resist.
Catching this monster is Rob’s best chance to atone for his past mistakes and level up his magic. Learning what makes mysterious, unbelievably sexy Orion tick is a nice incentive too. But his previous encounter with the dangerous demon they’re hunting nearly destroyed him. Can Rob save the day and get the guy, or will the monster finish him off for good this time around?