
He hates the people that contributed to his moms suicide but doesn't hate his father that did absolutely NOTHING to prevent shit from happening??? Also why would he kill his lil brother he was a kid back then or maybe not even born, why would you kill him? The rest of them yes.

i suspect it has something to do with politics and pride. idk about the dad, but i remembered the dad was devastated too, and even if he wanted to punish the culprit, he doesn't have a concrete evidence that shows exactly who the culprit and so the dad--as the king (personally, i think) cant be hasty with decisions like that because the culprit himself has a large and solid standing as noble in the empire. and about the brother, i also remembered that the prince wanted to forgive him BUT not the brother's mother as the prince would still kill her. but, the brother didn't want to, right. he wanted to save his mother, i think it would be inevitable to punish the brother for insubordination towards the crown and i think the punishment is usually death... moreover the brother is the center of the rebellion (even if he didn't want to and did it half hearted, he still in their side)
but this is just what i think
Take a shot every time someone says female
Imma die of alcohol poisoning