Well, screwing over Sherlock's friends seems to be the trend so far. And of all of us? I think he'd probably focus on John, because they're the closest, and John's watched his Sherlock die twice now, first from jumping off a building, then when Moriarty shot him here last summer. And three nights ago when he first went missing, Sherlock sent John a picture of the ground from the top of a building. And I mean, we've had contact since then, so he didn't jump. But I don't know. If the demon does enough damage to Sherlock's body, he could die and the demon could still be walking around in it.