Following the implimentation of the Organian Peace Treaty, D'kar felt that his father, Kor, and their House had been dishonored by James T. Kirk. D'kar attempted to take revenge on Kirk, but he was beaten in combat by the human, captured, and turned back over to the custody of his father, who did not approve of his son's actions. (TOS - Constellations short story: "The Leader")
- D'kar is described as appearing to human observers as being in his late teens. However, given the maturation rate of Klingons, as seen with Alexander Rozhenko, this could mean D'kar was far younger.