I have a fan theory that Stoker called in white phosphorus on his own position against orders, was scarred badly, and got thrown out of the military, which is why he’s now a mercenary and wears a gas mask.
But officially…
Proxy saved her family from death during the Dirty Bomb attacks by building a crude extractor fan out on a vacuum cleaner and duct tape.
Turtle built a prosthetic leg for Phoenix after he tried to remove his own tattoo (and screwed up badly).
Skyhammer was court-martialed for (presumably) calling in an airstrike on his own men by accident.
Stoker was kicked out of the army for doing something he shouldn’t have with white phosphorus. (See above)
Redeye was kicked out of the army for being a snoop that had dirt on his superiors.
Sawbonez was kicked out of the army for knocking out his CO, then using his kidney in a transplant to save a private’s life.
Sparks is fricking Jeff Bond (Nerds will get it).
Aura is a medical student that invented the healing station, then was tricked into giving the copyright to crooked doctors, and has to be a merc to pay the bills. (I wonder where she got the money to buy the shotgun?)
Bushwhacker is a high school teacher that invented the auto-turret. (I would love him as a teacher)
Vassili was a government assassin, but refused to kill his sister, and was therefore kicked out of the army (this is getting to be a trend, isn’t it?).
Fragger was a soldier, but quit soldiering, became a camera man, was laughed at by his army buddies, and became a soldier again.
Thunder is Russian. (But I really don’t think he is)
Rhino is smart, figured he’d make more money killing people than teaching people, bought a minigun that must cost hundreds of thousands of dollars with his college professor wages, and started killing people.
Fletcher is called Fletcher. (But his name is actually Gaspar, which is a WWWAAAYYYY cooler name than Fletcher)
Kira stole the controller for a weapons satellite, and is now being hunted by the people who own the satellite. (The devs should do an event that wraps up her story)
Phantom was kicked out of the army for stealing Refractive Armor.
Aimee’s boss was shot, she found who did it, and fried their eye.
Phoenix was thrown out of the hospital for being an insane dude that experimented on his patients. (Old gag, new twist.)
Nobody knows Arty’s story, although there are rumors that he has a family somewhere.
Nader is a gay lawyer.