Character Arc
Gu Dong-mae is born into the lowest rung of Joseon society, the son of a butcher family, and flees the country after enduring violence and humiliation. He is raised in Japan and returns to Korea as a skilled swordsman and the leader of a feared organization, a man hardened by the cruelty he suffered in his youth. His outsider status and complicated allegiances make him one of the drama's most morally ambiguous figures.
Dong-mae harbors deep, unspoken feelings for Go Ae-shin, whom he knew when they were young, and his place in the love story adds tension and tragedy. Though aligned with forces that often oppose Korean interests, his loyalties shift as his personal feelings and lingering ties to his homeland complicate his choices. He is portrayed with a mix of menace, longing, and unexpected tenderness.
Across the series, Dong-mae's arc explores the wounds of class, exile, and unrequited love, and he repeatedly faces choices between self-interest and a deeper sense of honor. His fate is part of the show's tragic emotional landscape. (Character details summarized for fan reference; verify against the series.)