Emperor

Yup. But he can be counted among psychologically affected people. The guy was obsessed. And I don't think he would've done that all had he been in his right mind. Like we all see he regrets it now. So he basically needed a psychiatrist all along.

The reasoning they gave was that he thought the uke(sorry I suck at names) was cheating on him with his cousin -.-

Believe it or not, Wonje was a sane person. He did not start by being born a psychopath, nor did he suffer abusive or traumatic childhood. And him becoming brutal, well, it's actually caused by 1 very simple thing: he simply could not understand and did not have a way to understand. His downfall: he let his inflated ego of an emperor overtake him - instead of trying to sort out the spy misunderstanding, he just used it as a mean to force Heun into his harem, and then treated him like his possession without caring about his feelings. His redeeming points in current lifetime: He remembered his shortcomings, & therefore he was willing to learn. That willingness to learn is a very big thing, especially for a tyrant.

That's exactly it. He was born sane. But going to that extremes doesn't represent a sane person. That whole misunderstanding affected him or rather brought out the awful deal in him. Do u remember when he said that heun was a drug for him? That's exactly the best representation. He behaves like someone craving for a drug and doesn't give a damn about how he gets them.
And yes he is willing to change in this life. It's like his sane self analyzed what he did in past life and he himself felt his insanity.

Yes indeed, Wonje said Heun was like a drug, & he got lost in his addiction/obsession with the "drug". I guess Wonje's reaction to the spy misunderstanding is a matter of interpretation. Some think that he made use of the opportunity to seize Heun & let out the real beast in him, some think it messed with his pride & thus it brought up the evil in him. But I think Wonje had a disadvantage since birth that caused him to become unable to understand & relate to suffering. I'm not really saying he was a snob who didn't care (well, maybe a bit, since tyrants tend to be raised that way), but he was just born without the capacity to physically understand it. And when he let the madness overtake him, that just exacerbated his cruelty to the point of brutality. The him in the current lifetime has the advantage of knowledge from Wonje. But that alone will not help if he himself doesn't have the willingness to learn & accept. I think that is his main redemption point now. If he can keep a hold on his sane thought process, I really do believe he deserves a second chance at happiness, after a bit more suffering of course, lol.

I totally agree. As an emperor he was used to having everything he wanted. The author being very realistic in this aspect. And I think he must be suffering a lot with all his guilt and heun not believing him.