10 Most Tragic Star Trek Characters

Kurn was first introduced as Worf's younger brother in the Star Trek: The Next Generation episode Sins of the Father. According to Kurn, their father, Mogh, believed his stay at the doomed Khitomer outpost wouldn't last long so he left Kurn behind in another family's care. He also explained that their father was being accused of betraying the outpost to it's Romulan destroyers.

An investigation by the Enterprise crew revealed that Mogh was framed by Duras, the head of a rival house whose father was the real traitor. Worf accepted discommendation, being legally stripped of his family honor, to protect the Empire from the ramifications of the truth. Following Worf's instructions, Kurn kept his true identity a secret. Their family honor was restored when Worf and Kurn sided with Gowron during the Klingon Civil War.

In the Star Trek: Deep Space Nine episode Sons of Mogh, Kurn informed Worf that because Worf opposed Gowron’s recent actions, their family had again lost their honor. A demoralized Kurn demanded that Worf give him an honorable death. Instead, Worf arranged for Kurn's memory to be erased and his appearance altered so he could be given a new identity.