Kolor's father, Gendal Delan was the leader of the Pendarran Warriors, who fought with the Jedi Knights and the Grand Army of the Republic during the Clone Wars. However, the Pendarran Warriors were exterminated in the Great Jedi Purge. This led Kolor to hate the Empire and he formed his own group, which was named after his father's.
Pendarran's Revenge occasionally aided the Alliance to Restore the Republic, however, after the Empire's defeat at Endor, Kolor became hostile to the New Republic. It was unknown if Kolor held a grudge against someone in the government, or if someone hired Pendarran's Revenge to act against the fledgling government.