|關於other characters named Mark，參見Mark。|
Mark was one of the members of Richard Grey's expedition to the Mariposa Military Base, along with Grey, Harold and Francine. While Francine was killed by one of the base's security robots, Mark was wounded and Harold sent him to the surface. It is not known what happened to him afterwards.[Non-canon 1]
- The Vault Dweller: "And then?"
Harold: "One of them robots got Francine. Mark was wounded, sent him back to the surface. Then it was just me and Grey."
The Vault Dweller: "What ever happened to Mark?"
Harold: "To this day, I don't know. He never made it back here, and...well I...couldn't face the wasteland again, so I...I never looked."
- Fallout Bible p.172: "MARK MY WORDS"
"What happened to the guy (Marc, I think was his name) who accompanied Harold into the military base? He said that Francine got killed by a robot and grey fell into a vat, but Marc just dissapeared. Did he make it out alive or did he perish along with Francine?"
No one knows; the mystery of what happened to Mark has never been explained. He was wounded, returned to the surface, and Harold never went to look for him.
::Cue mysterious music::
Oh, and I have a suspicion that Mark was a reference to Mark O' Green, the lucky fellow who wroteHarold's dialogue, but I can prove nothing.