A feature of the game is, when you die, a friend comes and drags you out of battle. He then sticks around and helps you fight the enemies a little. Sometimes he gets shot and goes down, but you can use your health syringes to revive him.
Well, this dude that has probably saved my butt at least 20 times by now comes and saves me again, but he gets shot by an enemy that I didn't know was there. So I revived him as usual, but the hidden enemy shot him down again. So I revived him a second time, an the same damn enemy hiding in the bushes put my buddy down one more time. I found the enemy, smoked him, and went back to revive my pal.
I stick my syringe in him, as usual, but he doesn't get up. He keeps squirming in pain. Confused, I put another syringe in him. Again, nothing. He then whispers, "Do it," and I'm given the option to mercy kill him or abandon him. Disbelieving, and with tears in my eyes, I make the decision to ease the suffering of my friend by giving him a final dose of morphine, and I watch him drift off into an endless sleep.
I never saw him again for the rest of the game.