He thrived in the apocalypse. When he killed that walker tied to a damn chair, and fought back Merle, I never felt more proud to have him as my favorite character on the show. Glenn finally transformed from a boy into a man in that moment! Glenn had what it took to survive, just as much as Rick, Carl, Michonne, and Daryl type characters on this show. It takes a lot more strength to not kill than it does to kill.
He did finally kill living people for the first time by the end of S6, and while I didn’t want or expect for his personality to be completely altered into that steel-edged Rick type survivalist, I was really hoping that was a sign that the writers weren’t going to kill him off in the 7A premiere with the bat, like his comic book counterpart. I was really hoping that making him kill living people for the first time on the show was a sign that the writers didn’t just think of Glenn as another nice guy, who they were going to brutally murder, and that they would use that potential along with the fact that he was going to be a father to further develop that dark edge to his personality that they always showed hints of, but never really delved into.