Darth Morsus was born Rurik Gra'tua on Mandalore. He was captured by the Sith during the Second Battle of Mandalore during the Mando-Sith War. After they noticed that Rurik had a strong connect with the dark side, he was apprenticed to Darth Dolor. After learning about Plagueis's Rule of One, as well as the secret to eternal life, from Darth Plaguies's holocron, he killed his master and later orchestriated the Battle of Wayland to purge the Sith. Afterwards, he set out for the Unknown Regions to learn more about the force.