"Don't necessarily have to have one specifically for demons, as long as you keep him out of your head," John said from the doorway to the other room, one shoulder against the doorjam. He'd heard them talking, but hadn't come out until now, to bring them back to one of the important parts.
"He can do what most demons of our world can do, only a damned sight better, and he can do much more than even I know. The host bodies are damned near indestructible as long as they're in them, and his likely even more because he's about as top level as you can get down there. But pulling a demon of his power out of the body won't get you far, even if you can find a way, which I doubt. Not even most exorcisms can drag him out. He'll throw you around like a doll with his mind, with as little as a flick if he gets the right opening, and if not, he can do it with brute strength. Keep him busy, he might get sloppy because he's an overconfident bastard."
He moved away from the door, eyes on Peter. "But if he gets in your head, he'll get the upper hand damned quick, no matter how strong your mind is. He knows what to look for and where to find it and he'll go straight for the things that he can try and cripple you with, long enough to distract you, lock you up and turn you into his next research project. So if you've got yourself some protection from that, I suggest you focus on making it as strong as you can to go hand in hand with the hex bags."