Weak Hero - Characters & Cast

Initially, Si-eun's motivation is simply to be left alone to study. This evolves into a fierce desire to protect his first real friends, Soo-ho and Beom-seok. After the group's collapse, his motivation shifts to vengeance and survival in a world he now perceives as irredeemably violent.

Si-eun begins as a withdrawn, solitary student focused solely on his studies. Initially, his violence is purely reactive self-defense. After forming a bond with Soo-ho and Beom-seok, he begins to fight proactively to protect his friends, discovering a sense of belonging for the first time. However, Beom-seok's betrayal and Soo-ho's tragic fate shatter his newfound emotional world. By the end of Season 1, he is emotionally hardened, colder, and his fighting style becomes more ruthless. He transfers to a new school, no longer a passive boy but a battle-weary individual ready to meet violence with violence, setting him on a much darker path for the future.

Soo-ho is motivated by a simple, powerful code of loyalty to his friends and his promise to his grandmother. He fights to protect the weak and maintain the integrity of his friendships. He isn't driven by ego or a need for dominance, but by a genuine sense of justice and care for others.

Soo-ho is introduced as a carefree, effortlessly strong fighter who sleeps in class because he works nights as a delivery driver. He values loyalty and has a strong moral compass, promising his grandmother he'll graduate. He is the catalyst for the trio's friendship, extending a hand to both the prickly Si-eun and the timid Beom-seok. His arc is one of unwavering loyalty; he consistently stands up for his friends and tries to mediate the growing conflict between them. His arc tragically culminates in him becoming the ultimate victim of the violence he fought against, falling into a coma after being betrayed by Beom-seok. His fate serves as the emotional core of the series' tragedy.

Beom-seok is primarily motivated by a desperate desire for acceptance, strength, and control—things he lacks in his abusive home life. As his insecurities fester, his motivation twists into a need to prove he is not weak and to hurt those, like Soo-ho, whom he perceives as looking down on him.

Beom-seok's arc is a descent from victim to villain. He starts as a timid, bullied transfer student who finds his first real friends in Si-eun and Soo-ho. However, his deep-seated trauma from his abusive politician father, coupled with intense jealousy and a desperate need for validation, poisons his perspective. He begins to misinterpret Soo-ho's protective nature as condescension and feels overshadowed. This insecurity leads him to seek power elsewhere, aligning himself with bullies and ultimately orchestrating the brutal attack on Soo-ho. His arc concludes with him being sent away by his father, consumed by guilt but having caused irreparable damage, embodying the show's theme that victims of violence can become its worst perpetrators.