James T. Kirk/Relationships/Family/David Marcus

Kirk's romance with Carol Marcus produced a son, David Marcus. At Carol's request, Kirk stayed out of David's early life. David knew something of Kirk, referring to him as "the over-grown Boy Scout" his mother used to know, but not that Kirk was his father. Carol kept David's father's identity a secret, fearing that Kirk's adventurous life would draw David away from her. In spite of the separation, Carol told Kirk that David was "a lot like you, in many ways."
In 2285, David was working with his mother at the Federation research station Regula I as part of a team developing Project Genesis when Khan Noonien Singh attacked the station. After fleeing to the Regula planetoid, Kirk rescued David and Carol. Kirk did not immediately recognize his son at their awkward meeting, and later became melancholy when considering an alternate life as a father. He observed David's dislike of him, complaining to Carol, "There's a man out there whom I haven't seen in fifteen years, who's trying to kill me. You show me a son who'd be happy to help him." After witnessing Kirk's victory at the Battle of the Mutara Nebula and the funeral for Spock, David consoled his father and admitted he was "proud, very proud, to be [his] son." ()
Later in 2285, David was an advisor on the starship , researching the Genesis planet he had helped to create. Taken hostage by Klingons, David interrupted an attempted execution of Lieutenant Saavik, wrestling a Klingon warrior briefly before being killed with a stab to the chest. The news of David's death led Kirk to stumble to the deck in grief, spitting at Commander Kruge in his rage, "You Klingon bastard, you've--killed my son!" Kirk subsequently killed Kruge and all but one (Maltz) of his crew. As Kirk and his crew made their escape from the collapsing Genesis planet, he somberly and mournfully said goodbye to his son. ()
Kirk kept David's memory close, with a picture of his son in his quarters aboard the Enterprise-A. Kirk's opinion of Klingons, once enemies he could occasionally respect and even share a laugh with, grew into hatred. In 2293, during the diplomatic mission to the Klingon Empire instigated by the destruction of Praxis, he logged, "I have never trusted Klingons, and I never will. I've never been able to forgive them for the death of my boy." Acknowledging that he wanted to believe Spock's statements that the mission was historic, he added, "(H)ow on Earth can history get past people like me?" The partial log entry, surreptitiously and illegally recorded by the evil Lieutenant Valeris, was used against him during the trial for the assassination of Chancellor Gorkon, and the incident forced him to come to terms with his hatred for Klingons; Gorkon's daughter and acting successor, Azetbur, realized and admitted just as the Khitomer Conference was getting under way that Kirk had restored her father's faith, to which Kirk responded that Azetbur had in turn restored his son's faith. ()