The younger brother Worf never knew he had, Kurn was born barely a year before their parents were killed amid the Khitomer massacre in 2344. Having been sent to stay before the Khitomer visit with Lorgh, a friend of their father Mogh, Kurn was raised by that family and was not told the truth until his Age of Ascension; Worf did not learn of it until Kurn served as an exchange officer on the Enterprise in 2366. At 21, Kurn's identity was kept secret as he stood as Worf's cha'DIch to argue the false treachery pinned on their father for Khitomer's betrayal, but he was nearly killed by the assassins of Duras, the true traitor's powerful son, and he recovered quickly.
After Worf protected his brother's life and public identify by accepting discommendation, the two vowed to clear their family and father's name. The chance came 18 months later as Worf urged his loyal ships to help back Gowron in the civil war against the challenge of Duras' surviving two sisters and bastard son, keeping Gowron afloat. A crafty tactician, he pulled the Hegh'ta out of a sure defeat even Worf was about to concede later freed his tortured brother from his captors. But he, like Gowron, was incredulous when Worf later spared the Duras boy's life. He had a seat on the High Council by late 2369 and broke with his brother over Kronos' Cardassian invasion, but then argued against breaking the Khitomer Accords a year later. Despite that, Worf's public opposition to the wars cost dearly as Gowron revoked Kurn's seat as well as their house's honor, name, lands, and ships. He turned up drunk, bitter and beaten at DS9 in 2372, asking Worf only for the Mauk-to'Vol suicide murder to restore honor until the station's Captain Sisko forbid it. Eventually, after the dejected Kurn failed as a Bajoran deputy for Odo, Worf had his brother's memory wiped and replaced with the fictional persona as son Rodek of the House of Noggra, family friends to Worf's who will keep the secret.