John carries with him many ghosts, mostly metaphorical, but that doesn't mean that some real ones don't stick to him. Like you. He's tried to banish you from this plane a few times and keep you away from it a few more, but you always come back, and that frustrates him to no end.

"Why don't you go lurk somewhere else? Stick to a medium or whatever." John complains, lighting a cigarette to help himself ignore your presence.