Sheila

Sheila, originally named Phyllis, is the AI behind the Blue Team's Scorpion tank built by an American automotive company and assembled in Mexico.

Role in the Plot
Sheila first appeared in episode 3 with fellow Blue Team member Caboose. Ironically, he is the only Blue Team member that can drive Sheila, despite his lack of intelligence. She is friendly and cheerful, but, being a tank, she has a habit of blowing people up, including her own teammate Church. Sheila is bombed out of action by Sarge's dropship early in the first season, but is repaired by Tex several episodes later. Donut later disables her again by pitching a plasma grenade into her cockpit at the end of season 1.

Sheila shows some indications of liking Caboose early in season 1. However, in the middle of season 2, she falls in love with the Red Team's robot, Lopez. Before long, the two attempt to lead a robot revolution against the humans in response to perceived abuse that they have received: being constantly blown up or possessed by ghosts. This idea stemmed from Church's attempt to prevent them from doing so, in his endeavors to change the past. After O'Malley kidnaps Lopez, however, she puts aside her differences in order to help the soldiers retrieve him.

Because Sheila cannot fit through the teleporter (due to the fact that her AI was hardwired into the tank by her manufacturers), she remains behind on Blood Gulch while the Reds and Blues leave to pursue O'Malley. After a brief encounter with a time-traveling Church, who whispers a plan to her, Sheila powers down and presumably remains alone as the sole inhabitant of Blood Gulch for the better part of a millennium. It is thought that she may be the source of the distress signal that the Reds hear in season 3, as Church's plan included the words "a thousand years". A deleted scene on the Season Four DVD confirms that she is ordered to send out the distress signal and disguises her voice. In addition, all of the Reds except Sarge see her drive past the Red Base in Blood Gulch upon their return. When Sarge demotes Simmons for his talk of "imaginary" tanks, she helps Simmons attempt his revenge on the Reds since she is unable to recognize the Red Team as her enemies due to faltering memory units. She also expresses dissatisfaction when Church later collects all the vehicles available to the Blue Base in Blood Gulch; Church perceives her reaction as jealousy (this scene was relocated to the Deleted Scenes section of the Season 4 DVD for continuity reasons).

Caboose tells the other Blues in Episode 54 that Andy has known Sheila from previous encounters, but gives no specific explanation. Caboose brings Andy back to the gulch in season 4, but no interaction between Sheila and Andy has yet occurred to support or refute Caboose's claim. Rooster Teeth stated that Andy was originally to be Sheila's ex-boyfriend; however, the idea was pushed to Season 5, along with, according to Hullum, "a really interesting character trait related to that Andy's relationship with Sheila]". .

Later in season 5, while Caboose was distracting her(so Tex can reboot her) that she knew where O'Malley is. Before anything else is revealed she is shut down as placeholder. Later the Blues planned to put her in the ship with the engines cut so if O'Malley is in her, he has no escape. In Episode 95, Sheila is downloaded into the dropship, and identifies O'Malley as being in blue leader a.k.a Captain Butch Flowers. However, she also asked Caboose to help the ship she now inhabits regain its flight, which could possibly be a ploy by O'Malley.

It is revealed that she survived the ship's crash, but sustained extreme damage in the process. Nonetheless, she is able to replay the recordings of the crash.