John Grimm

He's like the Mad Max of Doom!

History
Literally, five seconds after the events of Doom (2005), the portal that had been blown up somehow reactivated and sucked in both Grimm and his sister. He was startled awake only for a few moments after the teleportation, where he saw Foxy taking his sister away to be his "Arr, pirate queen and shit, aw man!" and then he fell back into unconsciousness.

Sooner or later, he retrieved his sister from Foxy, only for her to get kidnapped by Daniel. Somehow, we have a quote of him going "Aw shit, here we go again." Naturally, he saved her once again. Anyway, he found himself in Hell on account that he got 2 free passes to the Hells-Coaster Ride. Of course, it took him a few months to get there because people kept kidnapping his sister for some reason. At one point, he joined the Hell Troopers due to their insurance policy and tendency to not have family members kidnapped every day.

After riding the Hells-Coaster, the siblings both got an honorary pass to stay in the city of Gula for a few weeks. However, while Samantha Grimm (his sister) was able to stay there, John's time as a Hell Trooper finally started. His first few years began with touring the prison cities of Hell, along with a year station at Limbum, The Walled city.

[TO BE CONTINUED]

Trivia

 * If you have his initials JJG, and subtract the first J by 8 and the second J by 4, you get BFG. Pretty cool huh?
 * Not sure if he landed on Deimos during the Heaven Invasion or a completely different time.