Lassin was a Jedi Knight in the New Jedi Order, who died soon after the Disciples of Ragnos crisis in 14 ABY. In 41.5 ABY, Lassin—along with Jedi Master Kam Solusar, Mara Jade Skywalker, and the Sith Lady Lumiya—appeared to Jedi Knight Jaden Korr in a Force vision. In the vision, Lassin and the others had Force signatures more like Sith than Jedi, and they told Korr to go to the planet Fhost. This led Korr to discover an Imperial research facility on a frozen moon where Grand Admiral Thrawn had ordered scientists to produce clones by combining Jedi and Sith DNA. In the facility, Korr encountered a clone of Kam Solusar, and he believed the other clones may have been produced from the DNA of Lassin and the other people in his vision.