Having read the source material, I had to have drawn from...

Having read the source material, I had to have drawn from that. As a fan, I wanted to remain true to that character, but it was really cool because, as we were figuring these characters out, I realized that there was a lot more backstory, rather than what I had gotten just from reading the book. Glenn doesn't really get much of a backstory there. He's just seen as this kid who is put in this situation, not knowing where his mind-set is, but then you slowly see him start to develop.