Michael J. Caboose

Caboose is a member of the Blue Team who is a little empty in the head. When O'Mally infected him, he became evil, like Doc was when he was infected a little later. The members of blue team proceeded to go inside of Caboose's mind, revealing that it was, in fact, empty, and went off to destroy O'Mally. Before they could, O'Mally transmitted himself to a new arrival at Blood Gulch, Doc. The characters then proceeded to leave Caboose's brain.

Shelia
"I don't want a tiny Caboose walking around with a ten millimeter cannon for a head." Church, on Caboose and Sheila. Later, Caboose became friends with Sheila, the tank on the Blue Team, after Church sent him on a suicide mission to talk to Shelia to figure out what's wrong, thinking he'd be blown up. Later, Caboose started talking more and more with Shelia, becoming closer and closer friends with her.