Walker
From Halopedia, the Halo wiki
Private Walker is the Heavy Weapons Specialist of Corporal Harland's unit. However, after the encounter with the Hunters and fleeing a fight with a small unit of Grunts, Walker was frozen with fear and had a mental breakdown. Walker's breakdown nearly cost his squad their entire lives had Private Cochran not taken the initiative to shoot down the Banshees. Walker's breakdown slowly vanished upon returning to H.Q. at the city Cote d'Azur.