Unidentified Marine (Ghost's platoon)
From Halopedia, the Halo wiki
At some point between 2545 and 2549 she fought under the command of a sergeant nicknamed Ghost. She was close to him and greatly admired his leadership skills. However, she was saddened by Ghost's demeanor, as he did not display emotion, instead preferring to remain cold and distant. The Marine was mortally wounded in an engagement that resulted in the deaths of every member of the platoon save Ghost. With her final words she urged the sergeant to "... be human."
Her last words to Ghost appear to have motivated his actions three years later during the Battle of Algolis. Ghost was tasked with destroying navigation data and a powered exoskeleton prototype in accordance with the Cole Protocol. He disobeyed orders, instead using the armor to hold Covenant forces back while his men evacuated the area. He activated the armor's self-destruct function by speaking the activation code: "Be human." The resulting explosion killed Ghost and the surrounding Covenant forces. His last thoughts were of the promise he made to the dying Marine.
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