Kurn was born in 2345 on Qo'noS to Mogh, son of Worf and Kaasin. At a meal one night, Kurn threw a dish containing food, angering his mother, who ordered that he be given no more food that evening. It was at this meal that Mogh was tasked with tracking down a traitor working at the Khitomer outpost. Due to both Kurn's young age and a desire to preserve the family in case the rest of the family was killed, his parents decided to leave him on Qo'noS, under the care of Mogh's friend Lorgh, who was a Klingon Imperial Intelligence agent.
Shortly after Mogh and his family arrived on Khitomer, the Romulan collaborator Ja'rod revealed the shield codes to the Romulans, who lowered the outpost's shields. Mogh, Kaasin, and almost everyone else on the outpost died. Worf and Worf's nurse Kahlest survived, as did a number of other warriors who were taken prisoner. Lorgh decided to hide Kurn's true bloodlines, and raised Kurn as his own son. Sergey and Helena Rozhenko were informed by the Klingon High Council that Kurn's brother Worf had no surviving relatives, and the couple adopted Worf. (TLE novel: The Art of the Impossible, TNG episodes: "Sins of the Father", "Birthright")
When Kurn reached the Age of Ascension, Lorgh told Kurn about his true family bloodlines, however publicly Kurn's bloodlines were kept hidden. Kurn joined the Klingon Defense Force, and by 2366 he had reached the rank of Commander and was serving on a Klingon vessel as first officer. (TNG episode: "Sins of the Father")
When the Klingon High Council learned that Ja'rod had betrayed the Khitomer outpost, they decided that the House of Duras was too powerful to blame for this act, fearing that to do so would split the Klingon Empire and cause a civil war. Seeing that Worf was in Starfleet, and Mogh apparently had no other surviving family, it was decided to cast blame on Ja'rod's rival Mogh. Learning of this, Kurn decided to seek out his brother. Participating in the officer exchange program, he requested to be assigned to the USS Enterprise.
Arriving on the Enterprise, Kurn began shaking up the routine on the Enterprise, acting like a proper Klingon officer with everyone except Worf. Worf naturally took offense to this, and later confronted Kurn in his quarters. When Worf angrily told Kurn that he was Klingon and that if Kurn had any doubts that he could arrange a demonstration, Kurn replied that Worf's response was that of a true Klingon and older brother. After explaining to Worf that he had been hidden in Lorgh's family shortly as a young child, Kurn informed Worf that the High Council had judged their father Mogh a traitor.
Captain Jean-Luc Picard agreed to take the two brothers to Qo'noS to answer these charges. Worf asked that Kurn stand with him as his cha'DIch, but ordered Kurn not to reveal that he was a son of Mogh, to maintain his identity as the son of Lorgh. Duras, son of Ja'rod learned of Kurn's true bloodlines, and tried to have Kurn assassinated. Kurn was seriously injured in the attempt, but recovered in the sickbay on board the Enterprise. Picard took Kurn's place as cha'DIch, and found Khalest. Despite bringing her before the council, K'mpec and Duras were unwilling to reverse the judgment of the council. Worf decided to accept discommendation. Because Kurn's true identity had not been revealed, Kurn was able to continue serving in the Klingon Defense Force, with his honor intact, while Worf became persona non grata in Klingon society. (TNG episode: "Sins of the Father")
During the course of the following year, Kurn rose to command the IKS Hegh'ta. He came to feel that neither Gowron or the Duras family were worthy of leading the council, and began plotting with other high ranking officials to stage a coup to insure that neither the House of Duras or Gowron came into power. Shortly before Gowron's installation, Kurn revealed his plans to Worf, who decided not to allow Kurn to proceed with the coup. Kurn was able to convince several of the high ranking officials to join him in backing Gowron.
Kurn arrived back at Qo'noS to find Gowron's ship under attack. Worf, who was on Gowron's ship was able to destroy one of the attacking ships, and Kurn drove off the other ship. In response, Gowron, in his first act as chancellor, restored the honor of the House of Mogh. (TNG episode: "Redemption, Part I")
Klingon Civil WarEdit
During the Klingon Civil War, Kurn continued to command the IKS Hegh'ta. During one engagement in which the Hegh'ta was being pursued by two other Klingon ships, Kurn took the ship into the corona of a star, and having the ship fly away from the star at warp caused a reaction that destroyed the pursuing ships. He then took the Hegh'ta to Qo'noS for repairs.
When Worf criticized some of Gowron's actions, Kurn angrily replied that Gowron was now their leader, and that he supported Gowron at Worf's insistence. He stormed out of the room, and Worf was soon captured by agents loyal to the House of Duras.
During the closing moments of the war, Kurn led a force in attacking the Duras base on Qo'noS. He was able to find his brother Worf, as well as Toral, son of Duras. Smiling, Kurn informed Toral that Gowron wished to see him. When Gowron offered to let Worf execute Toral for the actions of the House of Duras, Worf refused, and citing his seniority in the House of Mogh, prevented Kurn from killing Toral. (TNG episode: "Redemption, Part II")
Aftermath of the Civil WarEdit
Following the war, Worf returned to Starfleet. Gowron offered Kurn a seat on the Klingon High Council in recognition of the House of Mogh's service to him during the war. (TNG episode: "Redemption, Part II" and TNG novel: Foreign Foes)
When the clone of Kahless surfaced in 2369, Worf decided to offer a proposal to the clone and to Gowron - that this Kahless would be allowed to reign as a ceremonial Emperor. Worf made it clear that if Gowron refused to accept this proposal that he would fight Gowron, as would Kurn and Kurn's supporters on the High Council. This would've almost certainly brought about another civil war. Fortunately, Gowron decided to accept the proposal, and allowed Kahless to take his place as ceremonial Emperor. (TNG episode: "Rightful Heir")
In a bid to stop his father from being killed in the early 25th century, Alexander Rozhenko traveled back in time to 2370. Adopting the guise of K'mtar, the gin'tak of the House of Mogh, the older Alexander attempted to convince both Worf and his younger self of the need to develop into a warrior, hoping it would prevent Worf from being killed by his enemies. This older Alexander explained to Worf that Kurn had no male children of his own, and that leadership of the House would most likely fall to Alexander. He explained that Kurn was concerned about Alexander's ability to lead the house of Mogh in that event. However, as this was an older Alexander trying to manipulate Worf and his younger self, he might not have been telling the whole truth regarding Kurn. (TNG episode: "Firstborn")
In early 2372, Chancellor Gowron decided to invade Cardassia, and broke off the alliance with the United Federation of Planets when they refused to support his action. Worf also refused to support Gowron, and as a result, the House of Mogh had its lands and title taken from them. (DS9 episode: "The Way of the Warrior") Kurn was forced to give up his seat on the council, and after roaming the Empire for several months in despair, he came to Deep Space 9, asking Worf to perform the Mauk-to'Vor ritual, in order to regain his honor. However Jadzia Dax and Odo interrupted the ritual, and Kurn received medical treatment.
Thus thwarted, Kurn accepted a position in the Bajoran Militia, as part of Deep Space 9's security forces. However, Odo soon terminated him for having a death wish and endangering the rest of the force. Following a mission with Worf, uncovering a Klingon plot to mine the Bajoran system, Kurn contemplated suicide with a disruptor, despite the fact that the act would be dishonorable under his circumstance. However, Kurn was too drunk to carry out the suicide, and lost consciousness.
Worf arranged for Doctor Julian Bashir to completely wipe Kurn's memory, and to perform cosmetic surgery to alter Kurn's appearance. Kurn then began his life as Rodek, son of Noggra, an old friend of Mogh's who agreed to take Kurn into his family. (DS9 episode: "Sons of Mogh")
Aside from the mirror universe, Kurn existed in other realities as well. In late 2370, Worf passed through a number of realities after encountering a quantum fissure while returning from a bat'leth tournament. In the second to last alternate reality that Worf visited, Worf had been unable to participate in the tournament as he was assisting in maintenance activities on the Enterprise. As a result, Worf asked Kurn to go in his place, even though he felt that his younger brother did not have his prowess with the blade. (TNG episode: "Parallels")