The three Park brothers seem to represent the id (Ki Hoon), the ego (Dong Hoon) and the superego (Sang Hoon) – every aspect of which is always present in an individual.
About the brothers, I wasn’t sure what to make of them in the context of the story. Initially, they just seemed like comic relief or background characters for Dong Hoon. Yet as the story went along, I began to see the reason why they were there. To me, they represent those emotions in Dong Hoon that he himself can never express. They are the different aspects of his personality that are long buried inside him. Someone over at tumblr put it beautifully in that the three Park brothers represent the id (Ki Hoon), the ego (Dong Hoon) and the superego (Sang Hoon), every aspect of which is always present in an individual.
From the beginning, they already knew the dangers of Lee Ji An for Dong Hoon. At the onset, despite the jokes and the teasing, they already sensed that there was something different between their brother and this young woman. Perhaps they sensed a different energy, a certain vibe. Perhaps they saw that Dong Hoon seemed much more alive around her. Much more involved. It’s unlike him. Dong Hoon once told them maybe the reason his will was strong was because he had never been tempted. Maybe as men, they could tell that this temptation has come in the form of Ji An, because temptations often manifest as something that compels the person being tempted to fall into it against all odds.
Dong Hoon himself never saw the great temptation to him of Lee Ji An because he was being very rational about it. She was just a “pitiful person”, someone he felt like he needed to help. She was his employee and he felt like as her employer, he has a certain responsibility in ensure her well-being. And anyway, it was just being humane.
It was only during their conversations that Dong Hoon (the ego) was able to understand his true feelings because his id and his superego manifested their perspectives through his brothers.
(Note: “The id, ego, and super-ego are three distinct, yet interacting agents in the psychic apparatus defined in Sigmund Freud’s structural model of the psyche.”
“According to this Freudian model of the psyche, the id is the set of uncoordinated instinctual trends; the super-ego plays the critical and moralizing role; and the ego is the organized, realistic part that mediates between the desires of the id and the super-ego.”
Actually, the motif of a triumvirate representing the three sides of a human psyche is really common – the superego and the id fighting with each other, and the ego as the middle person must resolve this conflict and decide the path forward. If you watch Star Trek (The Original Series) you’ll know what I’m talking about.
This triple manifestation is seen most clearly when the the brothers come face to face with Yoon Hee’s betrayal. Upon discovery of the affair, Sang Hoon and Ki Hoon react as if they were the ones personally offended. Ki Hoon takes it one step further and gets ready to confront the man who has inflicted pain to his manly ego. Sang Hoon, on the other hand, takes it upon himself to apologize to Yoon Hee for having come up so short in so many ways.
As they say, a picture (gif) is worth a thousand words: