You need to catch up to ep 11 @artwit. Things revealed about the vet left, right and centre. I'm just amazed, he spent 5 years going around, being so careless with leaving dead bodies behind, and not even bothering to check if Hyun Ji is properly dead or alive, by going through the hospital rotas. From what I see so far, though, he doesn't kill everybody, just anybody who he perceives will cause him harm. It's almost like a little kid lashing out, and plus what evil spirit cares what a human mother thinks? I'm not entirely convinced he's 100% possessed, there might just be a human soul corrupted by pure evil. His motives still remain the most interesting though and dying to know what THING Hyun Ji was meant to have in her backpack, and Park Ji Hoon had....also why kill the peeps, and ask questions later? They're in no position to answer are they?