The Red Team was one of the two teams of Simulation Troopers placed in Blood Gulch for the duration of the Blood Gulch Chronicles. The team initially consisted of Sarge, who led the team, Grif, and Simmons. Sarge later built Lopez out of their robot kit. The final member of the team, Donut, was a new recruit shortly after Blood Gulch Chronicles began.
Red Team's original goal in Blood Gulch was to defeat Blue Team, and they have continued to be antagonistic toward one another throughout the series. It was only after the Parabola of Mystery that the Reds and Blues were forced to work together against Doc (possessed by O'Malley). However, they still fought one another on every possible occasion until the two teams worked together with Washington to defeat the Meta and rescue Epsilon. Since then, while the teams are still not exactly friends, they have generally refrained from shooting at one another.