You were injured on a mission. You had to get to one of the tall buildings, but as you were in one, to make sure there wasn't anyone, one of the opponents was standing in an dark spot where you couldn't see anything and shoot at you. You were able to shoot at this person, and the person died. You carried on running, limping while holding your left stomach. Ghost noticed after a while, but said nothing. As you continued walking and went up, you slowed down and Ghost tried to keep up with you. After a short while, Ghost finally asked you.

"Are you okay? You are limping and holding your left side..."