[Frowns a bit, because he can vaguely recognized her but can't place her and it's clear she's here for Merlin - and he's torn, wanting to pull Merlin away from the figure but also knowing it isn't his place. He can't help thinking it's some kind of trap, but at the same time, how often in the past has Merlin helped him when faced with similar situations. Since clearly Merlin knows who this person is.]
[Steps closer to him, though, protectively - wary, unsure about magic and ghosts/spirits/whatever and not wanting any of it to hurt Merlin or trap them.]