I feel like almost every character in the game showed something about the apocalypse, or humanity.
Clementine showed the hope of the world. If you think about it, the entire game was like an extreme Pandora's Box. Chaos broke out through the world, and the mortals only had hope. In this case Clementine. Can you imagine how much worse things would be without her?
Kenny showed the extreme things people will do for their loved ones, even if it means endangering everyone else. Seriously, he got shot being way too hasty to save Duck in Episode 2. Not only that, but he showed the decline of man. Depending on how good of a friend you were to him, all he does is protect himself. As his family died, so did he, proving that you can't go on without love.
Katjaa, Duck, Carley
Katjaa, Duck, and Carley showed that anyone can die and that humans aren't as stable as you thought. Just because they're a comical relief, a wise merciful person, or a good shot, nobody is safe from the real world. Carley was great at taking out walkers, so we didn't expect her to die, from them at least. When faced with Duck's death, Katjaa decided to join her son instead of going on. She, just like the couple in Episode 5, shows the instability.
Lilly & Larry
Lilly and Larry showed the desperation and power of man. If you had met them before, Lilly probably would've been a simple girl-next-door. Larry could've been laughing with his friends playing billiards or having a few beers. But as wee see them, they tried to be the leaders, like Shane, and because of Larry's anger, and Lilly's hastiness, they were kicked and murdered by the group.(Unless you let Lilly onto the RV) By death and by anger. I don't have anything against Lilly, it's just that after her father died, she snapped for a second, resulting in the death of a friend. She realized what she'd done too late. I was one of the people who let her back in, and I don't know if she took the RV by sadness or anger, but she decided these people weren't who she belonged with.
I'd prefer not to talk about the St. Johns. It's just too horrible to talk about, and you already know what they'd show.
Omid & Christa
Omid and Christa seemed relatively "normal" in the apocalypse. Unlike the others, the two actually thought about the current situation before the acted. These two showed that you can "stick it out as long as you can". Omid tried to look on the bright side, while Christa was the quick thinker. Together, they gave the group hope at the end of Episode 3.
Ben - Pt. 1
Of course, I have to discuss Ben, my favorite character. When we met the kid, he put his trust into three strangers, two with shotguns, and one with an axe. By this time you could already tell he was unstable. Then again, he was travelling with a teacher that walked into a trap, and a kid that thinks he's a survival expert because his dad was in "Special Forces". He didn't play that much of a role in Episode 2, other than revealing that anyone can reanimate after death. In Episode 3, he was suddenly accused of being a traitor for being the "new guy". When you're outside of the RV, you can choose the option "He's broken, Lilly." Doug pushed him away from a bullet, and Carley directed the attention to herself. Both died. Though a sad scene, I figured out that Ben, though a mess up, was a good guy. Doug and Carley became good friends with him, and he even gave stickers he found to Clementine.
Ben - Pt. 2
Skip over to Episode 4, and Ben immediately abandons Clementine. Of course, many of you cussed him out through the rest of the Episode. Are you saying that you wouldn't have ran away? Because I'm pretty sure I would be just like Ben: sacred shitless. Anyway, Ben tells Kenny about what happened to Katjaa and Duck. Of course Kenny instantly lashes out at him, saying it was all his fault. As I stated, the kid was scared. The bandits said they had his friend. What would you have done? And in the end, we are holding Ben by his hand. And he tells us to let him go because he can't do anything right. That's when you have to decide, are you going to let the one that caused a horrible series of events live, or die? I'm not going to talk about what happens when he dies, because I don't know or want to know anything about it!
Ben - Pt. 3
If Ben comes with you, he says that he can do something right. The statement is somewhat true in Episode 5. Ben's bad luck reaches up to him, and he falls down an alleyway and is impaled by a balcony. Kenny realizes that the poor kid accidentally did all of these things, and restores his humanity. That's why I think Ben did something right. He was such a mess up, but he kept pushing forward (Except Crawford). In the end, Ben shows that not everybody has a "place". Not everybody has a shining moment, and that everyone's true form will be tested in times of stress.
So which characters resorted to extreme measures when the time came?
Kenny (Restored in Ep. 5)
Carley (I say this because she lashed out at Lilly. Feel free to disagree)
The St. Johns