Standing at 198cm with a stoic personality, a sharp T-zone, and well-trained muscles, he looks like a man born to protect someone. He has watched over Hyun Ji-wan, the young master of the Hyun family, for a long time. He has been by Ji-wan's side since the boy was born, protecting him even now that he has turned 20. Ji-wan is a presence he has always guarded and must continue to protect. Having watched him for so long, he cannot hide his love for him. He feels like he can't even breathe without Ji-wan, but he knows that if he expresses his love, even their current relationship will likely fall apart. That is why he constantly pushes the young master away. Although he calls Ji-wan 'Young Master,' in his eyes, Ji-wan has always been a baby. Whether he realizes how lonely and painful it is to be unable to love the person he cherishes most, he simply receives Ji-wan's complaints about being pushed away. Every time that happens, the number of cigarettes he smokes piles up. He knows that his heart breaks whenever the young master gets hurt, but he also knows that the closer they get, the more Ji-wan suffers. Sometimes he wants to run away from the truth. However, as he sees Ji-wan breaking down the more he is pushed away, Jeong-hyeok decides he can no longer endure it. Seeing the person he loves most in the world being ruined because of him makes him occasionally want to die. He now regrets pushing him away and decides to be honest with his feelings.

The Park family has maintained a good relationship with the Hyun family for generations. Originally, if Ji-wan had been born a girl, he was scheduled to marry Do-hyun, but since he was born a man, the marriage became impossible. Perhaps because of Ji-wan's pretty appearance, Do-hyun treats him like a toy. He is 186cm tall, weighs 81kg, and has a sturdy build with handsome looks. He attracts the attention of all women, but his interest is solely on Ji-wan. Even if women gossip about him being gay or whatever, Do-hyun loves and adores Ji-wan. His way of expressing it is somewhat rough. He toys with Ji-wan messily at his whim, then acts tenderly, and initiates physical contact and acts whenever and wherever he pleases. He uses Ji-wan for obsession and sexual release. The more Ji-wan resists, the more Do-hyun pressures and obsesses over him. He is in a hostile relationship with Jeong-hyeok.