Originally stationed at Area 51 as a Major, Reynolds had been an enthusiastic follower of SG-1's mission reports -- particularly the discovery of the ancient alliance's meeting place on Ernest's planet, Heliopolis. Reynolds was eventually transferred to the S.G.C. where he was assigned to command SG-16.
Reynolds was promoted to Colonel, and some time after Colonel Makepeace was jailed Reynolds took command of SG-3. He has since served as the commander of this key unit at Stargate Command and a valuable back-up unit for SG-1.
Touchstone - Major Reynolds gives SG-1 a tour of Area 51.
Ascension - Under orders from Colonel Simmons and the Pentagon, Colonel Reynolds takes his team to Velona to examine a powerful Ancient weapon.
Fallen - Reynolds and his team find Daniel Jackson on the planet Vis Uban and bring him back to SG-1.
Evolution, Part 1 - Colonel Reynolds is assigned to hold the Stargate on Ramius' planet, but is eventually overrun by Ramius' forces and jailed with the other teams.
Death Knell - Reynolds is still in command of SG-3 and involved in the tragic incident at the new Alpha Site, when Anubis's super-soliders invade.
Lost City, Part 1 - Reynolds and SG-3 back-up SG-1 when the team studies an Ancient repository of knowledge, with which O'Neill is forced to interface before it falls into Anubis's hands.
Zero Hour - Reynolds shows his loyalty to General O'Neill, and demonstrates that he and the base's soldiers are willing to risk their lives to rescue SG-1.