Relationship analysis:
Seo Hwi x Nam Seon Ho
They are close friends from childhood who have always supported and helped each other. But things changes when they are challenged with reality of the regime, their past, prejudices and intrigues of the powerful men fighting for the influence.
Happy careless times will end when their ambitions put them against each other and Seo Ho driven by his desire to be appreciated by his father beats Hwi unjustly and win the exams. Hwi is dragged out of the arena and Seon Ho's father then send him away to lifetime service in army so he isn't longer a thread to his family
Seon Ho regrets his actions. He takes care of Hwi's sister Yeon, but his guilt won't stop him from trying to get more power to be able to take revenge of his father (and also get his respect, he has some really serious daddy issues). Meanwhile, Hwi is going through hell in battlefield when leaders decide to abandon his unit. Seon ho thinks Hwi is dead.
When they finaly meet again, Hwi saves Seon Ho's life begging the doctor to heal his wound he got in the fight. Hwi still thinks about Seon Ho as his dearest friend and is happy to see him. Seon Ho isn't that happy. Maybe he was feeling the guilt and sadness when he thought that Hwi is dead, but now he probably doesn't know what to do.
It seems that Seon Ho kind of regrets his actions but he decides to stick to his new role and tells some terrible things to Hwi. He admits it was him who sent him to army (but it was actually his father) and now he was sent here to kill the rest of his men. Is it some kind of reverse psychology that makes him do even worse things than he originaly regrets? I have no idea. Seon Ho also tells Hwi that his sister is dead and he will kill him too if he will come back to take revenge on his family. It's probably attempt to protect Hwi and his sister from being killed by his father who is really capable of anything. But it really isn't the best way to protect your fried's life by hurting him more.
From that day, their paths starts crossing more often and Seon Ho is acting like Hwi isn't longer his friend. He convince his father to use Hwi and make him obedient by keeping his sister hostage, which probably saves lives to both of them. But I don't understand why is Seon Ho acting so cruel even though he clearly cares about Hwi and all of this just keep hurting Hwi more and more. More open communication would help a lot. This treatment makes Hwi to change sides and join prince Bang Won who is opponent to Nam Jeon (Seon Ho's father).
Hwi is acting like he has nothing to lose. He doesn't care about himself anymore and there are many situations when Hwi almost dies and Seon Ho is trying to save him over and over again. But now he has not enough power to protect his former friend.
They now stand on the opposit side of the power struggle knowing that one day they will have to face each other and we know this will happend from the opening of the first episode.
As the events progress they meet each other in a fight few times but they have such a love-hate relationship that they are not able to kill each other. They always wound the opponent slightly so he can't fight anymore, but he survives. Seon ho even tells to Hwi: "Your sword still feels affectionate."
Hwi is very generous to Seon Ho, he saves him many times, he stops him from suicide and he apologies for being too overhelmed by revenge that he doesn't saw how much was Seon Ho suffering. But, hear me out. Seon Ho surely has not an easy life, he surely was protecting Hwi and Yeon, but a lot of suffering that he and Hwi were going through was also his fault when he was blinded by his plans and ambitions.
Almost at the end, they again find the lost bond they once had. This however destroy the alliance between Hwi and Bang Won, who is Seon Ho's enemy and who was sparing Seon Ho's life because of his friendship with Hwi. When Seon Ho tries to assasinate Bang Won and fails, Hwi comes to save him. Hwi beggs Bang Won to let them go and promise that he won't be thread to him if he just let save his dearest friend. Bang Won release them and tell them to never come back.
Hwi and Seon Ho are thinking about living better life without intriques and violence, but they are already too deep in the game and they realise that their frieds will always be in danger if they are alive. They decide to make final action. They fight their way to the palace where Bang Won just took the throne and change their lifes for lifes of their loved ones (precisely...Seon Ho sacrifice himself so Hwi can reach Bang Won and then Hwi sacrifies himself for the deal). They die together like friends. It's really epic and I am really glad for this ending, it was kind of poetic.
So, lets make some conclusion. Seon Ho is really shitty friend. Yes, he did protect Hwi and his sister, but his behavior and bad communication helped to make total emotional wreck out of his friend. Seon Ho was very immature from the beggining and he really lack someone who would love him in childhood. I think his psychical instability origin in very young age. He is lucky that he has such a good friend who will not even forgive him, but also undestands him. I am not sure I would be so sympathetic towads him if he wasn't portrayed by Woo Do Hwan who managed to make this character more layered. Hwi's feeling for Seon Ho are not very healthy. But overall, I am glad that they find the way to each other at the end.
What do you think? Did I missed something?