MY weekend

Hey guys, it's Eric and you'll never guess who I ran into.  I was playing Fallout 3 with John after TOONAMI had gone off, and realized that I'd left my phone in my car.  I go on down to the parking lot, open my door, and nearly get stabbed to death by Advcate.  No idea how the piece of craps alive, but apparently wearing a mask makes you imune to 2 bullets to the head.  He lunges at me after I open the door and gets me to ground.  He tried to stab my head, but I'm able to move it out of the way each time.  He tries for the fourth time and I catch his hand with mine.  I'm able to throw his knife to the ground.  I punch his mask, and he gets up and runs.  I chase after him for about a mile, but he ran into the woods after that.  I told John what happened after I got back and he had a panic attack.  Can anyone tell me how he survived 2 shots to the head.  Please.