Mags was born in New Reno. She joined the NCR Army to become a Ranger, but failed the Ranger selection course and was assigned back to the regular infantry. Being promoted to corporal suited her, but getting transferred to Camp Golf did not. By the early 2280s, the base had a bad reputation as a dumping ground for lousy soldiers that the rest of the NCR Army doesn't want, and getting put in charge of a squad composed of some of the most unwanted soldiers in the whole Army has only made Mags resent her current situation more.
Flags of Our Foul-Ups: Mags will tell the player that the squad needs to improve in the shooting range and at throwing grenades. When asked to line the squad up, there will be 3 Guns checks when talking to her of 25, 35 and 45. After finishing the firing range the player will need to talk to her again to improve their grenade skills with 3 Explosives checks of 25, 35 and 45. Talk to her again after this about the squad to complete the quest.
If the player is taking O'Hanrahan's advice and convincing the squad to work together, the player will need to convince her to work better with the squad with a Speech check (40).
If O'Hanrahan's or her own advice is followed during the quest Flags of Our Foul-Ups, and Caesar's Legion is not victorious, she is promoted to sergeant after the Second Battle of Hoover Dam, and Mags and the rest of her team are each given a commendation. Transformed from some of the NCR Army's worst soldiers to some of its best, Mags and the rest of the Misfits serve with distinction for many years.
If O'Hanrahan or Mags' advice is followed but the Courier sides with Caesar's Legion, Mags leads the Misfits in a defiant last stand as Camp Golf falls. The squad's valor is posthumously recognized by the NCR Army.
Should the Courier hack the military computers as Poindexter suggested and make the Misfits look like they have improved, or otherwise fail to make any positive impact on Mags or her team, the Misfits' poor discipline and morale leads them to break and run when the Legion attacks Camp Golf during the Battle of Hoover Dam. Those that are not killed by the Legion are caught by the NCR Army and hung from the Ranger Monument as deserters.
If the Courier goes with Razz's idea, the Misfits inflict heavy casualties on the enemy when the Legion attacks Camp Golf. Mags and the rest of her squad are decorated for valor. They each become addicted to Psycho soon after, however, and take to raiding the highways, trying to get their next fix. The NCR Army eventually catches up to them and Mags and her team are all shot for looting.
If the Courier kills President Kimball in the Legion quest Arizona Killer, donning NCR armor and talking to her will cause her to comment that the Courier is lucky to be walking around the camp after what they did to the President.
Mags is one of the only junior noncommissioned officers (rank of corporal) to appear in the game.