people who complain about yona becoming queen because of her ~lack of political experience~ are lacking media literacy to the extent that they've missed the whole point of the series. it's acknowledged repeatedly that su-won is a "good king for kouka" but also shown that he doesn't care about people, and throughout the series you see the consequences of his mindset, of revenge, of treating people as disposable. you see the consequences of cruelty. you may be a "strong ruler" for your country but are you willing to trample on people and discard your humanity to do it? and that was su-won's character-defining flaw that he had to overcome. he defends his father's atrocious war crimes (the consequences of which are left for the happy hungry bunch to clean up, over and over) and yona tells him that's why his father could never have been king. you can see in his face how those words cut through him.
revenge is also what seals the nail in the coffin for king il, the one time he breaks from his ideals and murders his brother, revenge because his brother murdered his wife and showed no remorse. the reason su-won didn't look for a non-violent option and the reason king il didn't trust him as a permanent future ruler was because he's his father's son. while he claimed it was for the country's sake, he finally admitted to yona it was really about revenge for him, which was obvious the whole time. we see how he idolized his violent father. and that's how he serves as a foil to yona, who truly did put not only her country but all of humanity before revenge, who still held her father's ideals that su-won disdained but with the strength to take up arms and kill when necessary. the story is fundamentally about ending cycles of violence and embracing humanity. that's why su-won's father and su-won himself were not fit to be rulers. that's what the whole story is about. "it came out of nowhere" were we even reading the same manga
