Gordon Freeman
Unlike the other Marines, he works with the increasingly distrustful scientists and guards in order to make it out of Black Mesa alive. He and Gordon Freeman do cross paths during the game, but at that point, Shephard is merely an observer to a climactic event from the original game: the time when Freeman jumps into the portal that leads to Xen; however, if players tried to follow Freeman, they would appear in Xen but subsequently fall to their deaths. Shephard never fights alongside or against Gordon Freeman.