- "Hello, and thank you for activating the M808V Main Battle Tank. You may call me Sheila."
- —Sheila's first line in Check Out the Treads on That Tank
Sheila, originally named F.I.L.S.S., is the vehicle-only AI behind the Blue Team's Scorpion tank built by an American automotive company and assembled in Mexico. She's a main supporting character in the Blood Gulch Chronicles and a minor character in Reconstruction.
Sheila is a product of the military contractor that made the lowest bid, something she is ashamed of. When she first appeared, Sheila acted like an ordinary tutorial program, showing little emotion. However, in Season 2, Sheila developed a sense of kindness. Sheila is based on F.I.L.S.S. as both not only have similar personalities and voices, but Sheila's original name was Phyllis (F.I.L.S.S.) before Church changed it. Currently, she is still active at Valhalla in an airship, but is running at minimum capacity.
Although she is (commonly) a tank, Sheila has been shown to be kind and gentle throughout the series. While several characters easily go into a panic when seeing her, Sheila is usually calm as she easily gets along with others and keeps a consistent tone throughout. Sheila is also very caring, as she was able to help the unstable Simmons from committing suicide after his demotion. However, she enjoys blowing things up (mostly Church), continued to call Tucker a retard in Me, Myself and You, and helped Tex/O'Malley leave Blood Gulch.