Jin Seung-Ju is Jin I-Soo’s kind elder brother and the next in line to lead the Hansu Group. However, the last couple of episodes of Flex X Cop reveal his dark deeds and terrible true colors.
Jin I-Soo grew up in a hostile environment as his biological father, who took him in after his biological mother’s death, always treated him coldly despite trying to be a good father.
His stepmother remained a bitter enemy to him. However, amid all the hostility and estranged relationships, Jin Seung-Ju, his elder brother, always remained kind and affectionate towards him.
This is why when his true colors are revealed to him, Jin I-Soo’s world comes crashing down, as he’s left to grapple with the truth behind his mother’s and father’s deaths.
Jin I-Soo’s past
Jin I-Soo’s biological mother died drowning in the bathtub when he was just seven. To alleviate his trauma, his father Myeong-Chul got him hypnotherapy for the treatment.
He believed his mother to have died in a car accident, but the truth eventually finds its way to him. He later learns that she died of a sleeping pills overdose.
He blamed his father for it, believing he pushed his mother to depression and sleeping pills. However, Jin Myeong-Chul loved his mother dearly and was going to leave all of his wealth and ties to go marry her.
Before that, she died, and he took I-Soo in, raising him with his family consisting of a cruel and hateful stepmother Cho Heeja, but a kind and helpful stepbrother Jin Seung-Ju.
Seung-Ju’s story
Jin Seung-Ju is not Myeong-Chul’s biological son, but the son of a former lover of his mother.
Myeong-Chul had married his mother for convenience and appearances, and even after knowing she was pregnant with another man’s baby, he accepted her and the baby.
She always resented Myeong-Chul because he didn’t love her, and her spoiled proclivities always caused trouble for him. She raised Seung-Ju badly, in that she made him believe that inheriting the Hansu Group is his destiny.
Her paranoia that she and Seung-Ju will be thrown away after Myeong-Chul finds out he has another son with the love of his life he couldn’t be with, coupled with the obsession with becoming Myeong-Chul’s successor, does Seung-Ju’s head in.
Jin I-Soo’s mother’s murder
He visited Jin I-Soo’s home and spiked his mother’s drink with his mother’s sleeping pills, before dragging her to the bathroom and submerging her into the bathtub.
Jin I-Soo’s mother did tell him she wouldn’t marry Myeong-Chul and that he and his mother wouldn’t be discarded like he fearfully told her. However, he didn’t trust her at the end, and seeing his father’s urgency in wanting to divorce his mother, he committed a murder.
He grew up with I-Soo, being the only one in the family to be kind to him. However, as he later would reveal, he only was that way because he pitied I-Soo.
When he helps his mother get rid of her former lover, who had been blackmailing her with leaking the information about their son Seung-Ju to the media, his biological father is killed.
Myeong-Chul’s murder
It becomes a big case and Myeong-Chul has to withdraw from the mayoral race. He also finds out about Heeja and Seung-Ju’s parts and announces to the latter that he’s disowning the two.
Seung-Ju only wants the throne and to protect his mother, so he kills his father by spiking his drink in the same manner as he did I-Soo’s mom all those years ago.
He becomes the chairman, but I-Soo finds out that he’s the one who killed Myeong-Chul and that he might’ve also killed his mother. He invites Seung-Ju to his childhood home to confront him about the truth.
Seung-Ju’s crimes and confession
Seung-Ju comes clean and admits to his crimes. He tries to kill I-Soo but fails to do so. I-Soo shows him the mirror and the horrors of his actions before the police arrive and Seung-Ju is arrested.
Seung-Ju confesses to all his crimes and is given a life sentence, while his mother becomes wheelchair-ridden after learning her son killed her husband, and that her actions led to this day.
Jin I-Soo takes over Hansu Group but makes Mr. Cho the new chairman, as he returns to his position as a cop in the Gangha Police Station.