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|Out of universe information|
- "You're user number 4574, the one who's been accessing our personnel files. You don't care about Tyler, you've just been waiting for something to use against us. Who are you getting your orders from Colonel?"
- — Samantha Carter
Simmons was recruited into the N.I.D by Colonel Harry Maybourne. He was later at Stargate Command helping coordinate the use of the weapon found on Velona and then the capture of the alien in Samantha Carter's house. When SG-1 returned to Earth claiming there to be a fifth member of the team, Simmons interviewed each of the team members and made claims that each member had already been compromised due to previous events. He warned General Hammond that administrations change and that he would not be around forever. (SG1: "Desperate Measures", "Ascension", "The Fifth Man")
Simmons paid $3 million to Maybourne to purchase a Goa'uld symbiote and then shot Jack O'Neill in the back and helped the symbiote, who had taken Adrian Conrad as a host, escape. Simmons had the symbiote locked in a cell, working for him. When Teal'c became trapped in the internal workings of the Stargate, Simmons asked the Goa'uld how to solve the problem but kept the information to himself. He went to Stargate Command with orders that the base should continue normal operations. O'Neill discovered how to save Teal'c and got information to have Simmons arrested. (SG1: "Desperate Measures", "48 Hours")
Simmons spent time in prison until a group of N.I.D personnel took over the Prometheus and got Simmons and Conrad out of prison and on the ship. Simmons had the Goa'uld work on the hyperdrive and took the Prometheus into orbit and then left to find a cache of Ancient weapons. Simmons was attacked by the Goa'uld and managed to shot its host, however the symbiote left him and entered Simmons. He and the symbiote attack O'Neill and Teal'c but was defeated and launched out of an airlock and killed. (SG1: "Prometheus")