From Halopedia, the Halo wiki
Prior to 2552, Gretchen served in the same unit as Dutch and his friend Kojo "Romeo" Agu. At some point, she and Dutch developed a romantic relationship and later married. Gretchen enjoyed fighting, to the extent that she actually laughed in the midst of combat. However, her outlook changed when she stepped on an Insurrectionist landmine during a mission; her left leg was blown off by the resulting explosion.
Before the Battle of Ariel in January 2552, she was still confined planetside because of her injury. She sent a message to Dutch, in which she informed him that there was an open position in a motor pool, and suggested that he should accept it. By October 2552, though she was looking forward to return to active service, the doctors predicted she would be confined to non-combat duties for the rest of her career. However, by 2553, she eventually retired from service. After a friend and squadmate of Dutch's died during a rebellion on Draco III in 2554, Dutch retired from service to be with Gretchen. The two continued to contact their old squadmates and friends after their retirement, including Edward Buck.
In 2558, Dutch and Gretchen unexpectedly resurfaced during the Created conflict when Buck, Romeo, Dare, Vergil and Sadie Endesha visited the Spartan-IV training station to break out Mickey Crespo. After Buck was declared a rogue Spartan by the AI Leonidas, in reality a rogue AI loyal to the Created, Dutch and Gretchen came to his aid and explained that after Gretchen was given a new prosthetic, they had joined the SPARTAN-IV program, having not told their friends in case the prosthetic didn't work. Dutch and Gretchen joined the reformed Alpha-Nine as they fled the station in a Condor to undertake a secret ONI mission.
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