Despite his name, Sergeant Mark does not fit the description of a sergeant. A "sergeant" is a low-ranking officer in a police force, army, or marines. Mark is just a high-ranking worker at a spaghetti factory.
He has shown to appreciate Swagmaster and Chris, allowing them to come back in Guards N' Retards: Swag Magic after being fired, but Swagmaster shot him, and he likes how they work shown in Guards N' Retards: Prisoners.
Mark's model is the "Moonraker Elite" from GoldenEye 007 for the Nintendo 64.