"Doc" Frank DuFresne is the medic for the Reds and Blues. Although not an official member of either group, he frequently assists each team. He is a pacifist, and does not hurt other characters, with the possible exception of his overloading of the Meta's circuits in Reconstruction. His armor is purple, and for some time was controlled by O'Malley. Donut, previously assumed dead, lives with him in Season 10.
He then returned to "save" the reds and blues with donut in season 11, and was then promptly beat to a pulp by everyone, but was then seen with red team looking for a way to combat freckles, and found ci-ci, who tried to kill them, during this, Grif found teleportation grenades, doc then warned him to be careful with them. later, while sarge works on CI-CI, doc and grif test out the future cubes. after giving donut a demonstration, doc is sent into a teleportation grenade, only to be mentioned by Lopez once in a while.
Doc returns in Season 12, turning out to having been in a singularity beyond space and time that maddened him and made an O'Malley-inspired alternate personality to emerge.