Responses

Yeah, but the question is if Soo-Won really knows that.
If he heard the story from his father, it would be: "Those people wanted to harm your mother and overtake the kingdom", if he heard it from his mother, probably: "It was horrible, but your father is not to blame".
Well I guess in the end it his reasoning for killing Il will mostly be that Il was a bad king.
Heavens, now everything is starting to make sense.
If anything happens to Kashi, Il will immediately assume that it was his brothers fault -> kill him.
Soo-Won will grow up with a mother that is plagued by guilty feelings, and in the knowledge that his father was killed for a woman, that 'harmed his mother' or something like that.
╥﹏╥ ┗( T﹏T )┛ (╯°Д °)╯╧╧
YONA! Make sure you untangle that whole mess!