Deimos's background is unknown, though certain posters in the background suggest he may have been a member of the A.A.H.W. before defecting from it.
However, Deimos and Sanford survived and fought their way through the A.A.H.W. forces. Eventually, the two raided an A.T.P. Soldat facility and blew it up.
Sometime afterward, Deimos and Sanford hijacked a truck carrying a squad of A.T.P. Engineers. They then headed towards where Hank's body was located at after he was killed by Jesus. While Sanford held off the A.A.H.W. soldiers, Deimos went to revive Hank in a magnification chamber. Deimos succeeded in magnifying Hank, but was killed by one of The Auditor's possessed Engineers shortly afterwards.
In his "Deimos Adventures" spinoff, he finds his way of out of Hell after being killed in Madness Combat 9 while enduring the horrors that awaits him.
- Deimos is one of the most popular characters in the Madness Combat fandom.