*Spoiler alert*
His dad killed and his son was an accomplice to these murders. His son ''played'' with his dad and he loved it. His mom tried to kill him after finding out and threw him from the roof. After the accident the son changed and his memory distorted. He hated his father, and believed that it was his father who tried to kill him, that what they were doing was wrong, and confessed that he thought what he did as a child was wrong. He hated his father for making his an accomplice to murder and for having to bring his father potential victims. The scene when his son remembers everything was intense. Memories of how the son enjoyed what he did with his father when he was a child, and that it was his mom who threw him from the roof not his dad. His dad was always portrayed as the villain but he really loved his son. He bought that painting named father and son, and they ''played''(killed) together which he thought his son liked, he ran to the hospital when his mom threw him, killed his ''friend/classmate'' because he thought he was bullying him, it's twisted things but still...it's his way. It's weird because all we ever saw or what it looked like was that he hated his son, and I guess that's what I love about this manga, it catches you off-guard.
In the end, his dad, instead of being caught by the police, he jumps from the building and dies, holding the painting ''father and son'' (emotional scene). His son confesses to everything, and plans to spend his time after with his girl. Bittersweet, but also I can't see any other way it could have ended.
Bastard (hwang Youngchan)