THE 3RD ONE I THOUGHT ITS RELATED TO RAWS BUT IDK IF THERES RAWS ALSO I LOVE YOUR THEORY!!
I have another theory that white haired guy became some sort of spirit after dying that only mc can see, and when the villagers or people in the palace see him talking by himself they think he's crazy and he starts to think he's crazy and decided to kill himself. Devastated, white haired guy then continue roaming the earth for centuries hoping to see the reincarnation of his lover and then he does and got jealous with how close current shin is with mc, then the accident occured and he didn't try to miss the chance and took over Shin's body.
isn't that possible? he can't be a spirit since he was called as a prince though but idk we do we
1st. The black haired guy with mc from the past is somewhat related to this white haired guy who got reincarnated as Shin
2nd. In the past the white haired guy and the mc has a maybe romantic bond and the black haired guy got jealous because he's lusting over mc so ya maybe the two of them are actually married and it's against mc, but black haired guy is more powerful than mc so he doesn't have a choice.
3rd. Mc actually killed the black haired guy and black haired guy then cite a curse or soemthing and the white haired saw it and took the blame, and then got death penalty because black haired guy has a powerful title back in the past.
AAAA I'M SO EXCITEDDD