Ensnared by Magic - The One Rises, #3

Mark would give anything to go back to the way things were before he got bitten by one of the demonridden. Instead, he has to figure out how to control powers he doesn't want and nightmares that leave him waking up in the middle of the night in a cold sweat. Now, to repay a debt, he has to offer his services to a powerful coven leader-an earth witch who has been very vague about what he must do to fulfill their agreement.
As tensions heat up amongst the witches, Callie, Silas, Edie, and Mark find themselves in the middle of machinations to decide who will control the fate of humanity."There is another world touching ours that is filled with demons or, at least, that's what we call them. They call themselves something else entirely, though that is neither here nor there. Every now and again, human beings manage to pull these demons through to our side.
The human dies, of course, and the demon gets a person shaped suit to live in. We call these creatures the demonridden."