An undiscussed alternative, of course, is dhveery. He probably was able to pick up the Cloak, and has a strong incentive to port Harry someplace special if Harry cracks.
My personal guess is Lupin, though. I think the Black/​Pettigrew story is wrapped up in MoR with one of them dead and the other in Azkaban, but Lupin has the connections and freedom and desire.
An undiscussed alternative, of course, is dhveery. He probably was able to pick up the Cloak, and has a strong incentive to port Harry someplace special if Harry cracks.
My personal guess is Lupin, though. I think the Black/​Pettigrew story is wrapped up in MoR with one of them dead and the other in Azkaban, but Lupin has the connections and freedom and desire.