Thanks for the warm welcome. 😊
My thoughts would be the current king was most likely involve too on the attempt of killing Haram's father. As they were discussing about the rain ritual he has this line "So this time, it is his son". So he's contemplating and maybe harbouring some guilt. In the end his council was able to persuade him to not sacrifice Haram. He specifically ordered that to the shaman but the shaman did not obey because she knows a human sacrifice is needed for the ritual to work. So she performed the ritual and so Haram died but thanks to the demon's power he was revived.
As for Jooyang. That's because of greed. He was frustrated everytime he sees his brother. Because Jooyang is ambitious. He compared his life to a guelder flower he feels like he is only for decoration and can't do anything. He was enticed by the words of the demon. If ever he gets his hands on the demon he'll be powerful enough to snatch the throne.