Filin was a human male criminal who worked with his older brother, Karrst. Due to the many murders they committed, and due to Karrst's sensitivity to the Force, the Knights of Ren, a dark side organization led by an individual known as Ren, sought to recruit Karrst into their ranks. Ren required Karrst to kill his brother to prove his worth, but Filin instead killed Karrst, attempting to join in his place. However, as Filin was not Force-sensitive, Ren killed him.