John Beaumann's former squad leader and a rather unscrupulous individual, Rush got killed by Ziritsa NaDoldor after he killed her mother during the events of With The Clarity Of Vengeance. Or so she thought. Unknown had other plans for such a dependable worker. They brought him back. Heavily augmented, he proceeded to lead a squad of Unknown soldiers on a mission on Unknown, where he forced John Beaumann and Cynthia Schawrz to kill many, including Unir NaDoldor, before making the couple turn their guns on each other.
Rush is still a very active member of the Unknown and last discovered to be part of a project called Star Signals.