Rather, I think he was too late to help his friend causing the friend to fall even before he reached the top
Or he dismiss all the sign that the friend was possessed, leading to the friend injury
I'm guessing white hair had some ghost related ability/shaman type background that he kept secret, and he blamed himself for black hair constantly being bothered by ghosts. So black hair gets possessed and falls off a roof, and white hair decides to ghost him for his safety. But now he's learning that black hair is just *like that* and Blk hr is actually safer with his own personal exorcist to shake out the ghosties
Ooh kinda make sense too
Since he was actually surprised when the black hair get possessed again
im guessing white hair kicked black hair off the balcony when they were younger (to exorcise the ghost) but forgot kicking a person (off a balcony) will injure them.....im guessing