SPOILER WARNING: Plot details follow.
Arlene first met Fly when she joined the Marines and showed up at a barracks he was at sporting a high-and-tight haircut. Fly 's CO, Gunnery Sergeant Goforth , a many-year veteran from the deep South, spouts his disdain at seeing a first-year female Marine with the haircut and begins haranguing Arlene , who takes it all in stride. Goforth gets an idea in his head to test her out; he believed that "any muh-REEN!" is a rifleman first and creates a contest. Emulating William Tell, Goforth placed an apple on Arlene 's head and shoots it clean off with his rifle. As his men congratulate him loudly (sans Fly , who found the whole thing ridiculous), Arlene propositions Goforth with the same thing. She places an apple on his head, grabs a rifle, and shoots it off almost dead-center. Goforth , swallowing his pride, eventually admits "it's YOU, Private", and never harassed her like that again. She was then accepted socially into the Marines, and this act of bravery made her an instant friend with Fly .
Their friendship seemed to be a ceremony of opposites, as their personalities and outlooks on things were quite different. Arlene was raised Episcopalian, but as years progressed she felt disenchanted with religion and became a staunch atheist. This is in contrast to Fly , a long-suffering Catholic who took his faith very seriously. She also at one time went to college and expressed interest in going back after leaving the Marines, displaying an above-average intelligence regarding technical aspects, again in contrast to Fly , who was more level-headed.
She is also much more romantic than Fly , stemming from her relationship with Willhelm Dodd and marriage to Albert Gallaten, both of whom she originally hated upon first meeting. When Fly and Arlene were shot into space after attacking the Freds' ship, leaving Albert behind, she sinks into a deep despair over the loss.
Also a member of Fox Company, Arlene is the Fox Company's best scout, and one of the few people that Fly truly trusts. Like Fly, Arlene gets caught up in the invasion of Phobos and Deimos, and uses her scout training to sneak around and leaves waypoints of sorts, in the form of Arrows marked A.S., influenced by the film "Journey to the Center of the Earth". When they become attacked by the invading forces, she asks Fly to make a pact: If Dodd has become a zombie, that Fly be the one to take him out.
Despite the pact made, Fly hesitates to destroy her former-lover, leaving her to finish the job. This is a relief for Fly , because they both knew if he had been the one to take him down, it would have created a barrier between the two of them. Despite her smaller lithe frame, Arlene is nearly, if not as strong as Fly himself. While she is a better thinker than Fly , she does not have the same cool head that he does.
Arlene has/had a brother, Ambrose (or "Buddy"), whom was easily swayed and ended up joining the Mormon religion after many years of personal wandering. Because of this, she felt the Mormons (whom she deems a cult) had taken advantage of his "weak mind." She never mentioned having a brother to anyone during her stay in Fox Company, not even to Fly, but felt comfortable telling Albert about it in order to explain her disdain towards his religion (he ended up taking it in stride).
Arlene is one of only two characters who makes appearances in all four Doom novels.
She is a big fan of science fiction writing and films, as well as H.P. Lovecraft (she name-checks him when claiming that the alien invaders were "eldritch"). Though Fly does not really care for those kinds of films, she nevertheless "drags" him to sci-fi movies and conventions.
Arlene is described as having reddish hair, in the style of a military high and tight. Her eyes are said to be green, and she keeps them squinted almost all the time (Flynn has even stated that, when her eyes are open or widened, she looks like a different person). Standing at 5'10, it is also noted she is slim but has well cut muscles.
The character by the name of "Crash" from Quake III is presumed to be based upon Arlene Sanders, though this is just as often contested. Id Software has not verified, nor denied speculation on the subject.
Eric Harris of Columbine High School massacre infamy was a very serious Doom fan and was reported to have named his sawed-off shotgun after Arlene Sanders.