woah, really?
The point of Stockholm Syndrome is to defend your abuser and justify his actions. That is the total opposite of Bum's reaction that is perfectly capable of deceiving the detective and everyone else about his actions.
I wish people stop throwing SS as excuse for Bum in this novel. His pathological dependency and obsession with Sangwoo was there before they met. He would have stayed with Sangwoo no matter what. Bum being able to manipulate the situation now shows that there was nothing about Stockholm Syndrome in his actions. He was doing whatever he could to get what he wanted: to stay with Sangwoo because that is his psychosis.
Besides the fact he tried multiple times to escape during season 1 (he even tried to poison him! And he tried to escape in chapter 7 and 15), Bum was simply confused because he loved the kind Sangwoo ( he fell in love because Sangwoo saved him from the rape at the military) but he was afraid of Sangwoo's abusive side. Bum now is traumatised to the point he doesn't remember anymore the face of "kind" Sangwoo ( the picture is very significant because it was made when they go to the amusement park) and he is just remembering the abusive side, that's why he is telling lies. Plus I'm sure he is not trying to manipulate anyone, it's more a defensive mechanism of his brain after the trauma and he is telling fake or altered memories.
just an fyi, i’m not saying he HAS Stockholm syndrome. it’s merely an observation :)
apparently not remembering your abductor’s face is a symptom of Stockholm syndrome