The scholar's father(?) was killed by the prince, if I remember correctly. He was about to off himself when the serpent found him and tried to give him some reason for living. As I recall, he has a soft spot for humans and wanted to save him even it meant helping him plot revenge.
Its all the crown princes fathers fault if I remember correctly. The mf was jealous of his own son. He set a trap and sent him to village which the scholars family died ( I think he was the pharmacist that was helping the uke give out medicine) cuz the crown prince killed everyone that was involved, the father also set blame on others. The scholar went to the snake for revenge snake is also bitter that he couldn't become a God. So they teamed up.
Oohhhh yeah I remember now. Wasn't the "medicine" he was giving doram sort of the reason why the disease was spreading? At least that's what it seemed to me based on the crown prince's reaction on the medicine that fell in the stream? I'm gonna try and read those chapters again. Because if it's so, the scholar may be angry at the CP because he didn't know that his father committed something grievous and deserved punishment.
Why's that serpent and scholar so cross with the crown prince again?