I think he's dead. I also think the writers intentionally showed the intestines being ripped out near his chest area (whether they were Nicholas's or not), to confuse us and also lead to speculation about whether Glen is alive.
If he is indeed dead, then the writers certainly pulled a god one out of the hat. Probably to show that even though he is a main character on the show (and survived through a great number of close calls), a death isn't always ceremonious. One quick mistake, and you're gone.
|