Rush served in the military prior to the nuclear holocaust, and now works alongside the Security Captain to help rebuild society across the United States with a group of experts that are from a community in California dedicated to biofarming and engineering that he is the leader of.
Rush was contacted by Carmina Rye and was asked to help Hope County fend off the Highwaymen. Rush agreed as he saw Prosperity as a suitable foothold for his group to expand east. His train was attacked by the Highwaymen and Rush, Garrett Barnes, and the The Security Captain had to make their way through the train wreckage and escape to safety. The trio were cornered to a ledge of a cliff and the twins -- Mickey and Lou -- tried to coerce Rush to use his expertise to aggrandize the Highwaymen. When Rush refused, the twins killed Barnes. Rush tried to knock down some of the Highwaymen as a distraction and pushed the Captain off the cliff so they may escape capture.
Rush is captured and sent to an underground lair in the northern coal mines where the Highwaymen were torturing him to be compliant. The Scavengers need Rush's expertise to upgrade Prosperity and rebuild the communities in Hope County. The Captain sets off to rescue Rush but they find that he had beaten his torturer to death. Rush's knee is dislocated from the torture but with the Captain's help, they ride a turret mounted motorcycle and power through the Highwaymen back to Prosperity. There Rush recovers and instructs the Captain on what they could do to effectively upgrade Prosperity.
Rush's leadership optimized Prosperity's infastructure; enough that they were able to fend off a massive Highwaymen assault. The attack diminshed a lot of their forces however, forcing Rush to advocate they make an alliance with New Eden in order to give Prosperity a necessary advantage in the war. Rush urged the Captain to find out the New Eden cult's secrets as he saw how some of them accomplished superhuman feats.
During one recon mission, Rush was captured by the twins and was used to lure the Captain to the old fertilizer plant. Using Rush as a hostage, they coerced the Captain to handcuff themselves so they can watch as they make an example of Rush. Rush was killed by Lou with a shotgun after the twins handcuffed the Captain, but his death drove the Captain into a rage and they managed to break their bonds and powered through the twins before they were shot through a window.
The Captain survived their wounds and went to recover Rush's corpse. When they returned to town, the residents of Prosperity held a funeral for Thomas Rush.
- The insignia on his jacket bares a striking resemblance to that of Task Force 141 from the Call of Duty series which had previously been referenced by Willis Huntley back in Far Cry 3.
- A note at the beginning of the game, found in the wreckage of the train, suggests that he may have a daughter (or other female relation) named Mila, who is living with an aunt and uncle while he's away. Rush also has a small bracelet with Mila's name on it hanging from his left breast-pocket.