Not much is known about Atwater's background or early life except that they were a soldier in the United States Military.
In July of 2033, Atwater was in a patrol with O.I.C. Waters, Private Shah, and Private Coolidge on the outskirts of the Boston area. They heard and/or saw an Infected near a collapsed office building. The patrol went to investigate and was soon attacked by multiple Infected, where Atwater was killed.