Having fought several proxy wars on Earth, Marion Greenland is an accomplished security specialist amongst her employer; Excalibur a private security firm who are often tasked with providing security for high profile clientele. She was later recruited on behalf of her employer to work for the RDA. For several months, she exercised her training on Earth's Moon before being transfered to go to Hell's Gate. At the time, she was known quite well for her versatile skills that were flexible no matter the situatoin of her circumstance. Even her newfound employer, the RDA, felt she was more suited to work on Pandora than most officers of SecOps.
Having been promoted to Sergeant Major, she eventually arrived to Pandora aboard the ISV Altair Borealis, where she soon found work under Dominik Temple who was leading a crusade in restoring the colony back to its true purpose. She was put in charge with helping strengthen security on the base due raids by creatures outside the wire.