This discussion may contain spoilers!
I stumbled across this interview with Jake Rodkin about the final scene of Season 1, where Lee is given the option to have Clementine either shoot or leave him:
Rodkin: There's one funny detail that we may as well mention. This is a timed choice, and if you let the timer run out and Lee says nothing, Clementine does decide for herself. If you aren't there for Clementine when she asks you what you should do, she does actually look back at everything that's happened and she'll decide if she wants to do it or not. You can force it on Clementine, but you're a big ass if you do that.
This is mentioned in the TWD Wiki as well: http://walkingdead.wikia.com/wiki/Clementine#Trivia
So I did 2 different playthroughs to test this: During the first playthrough I treated Clementine as good as I could and played very human and diplomatic, without killing/fighting/threatening anyone (well, except for the bandits and the stranger), while during the second playthrough I did the exact opposite. But in both cases the outcome was exactly the same: I let the timer run out and Clementine decided not to shoot him.
So my question is: What exactly does she "look back at" when making this decision for herself?
What do you have to do in order to have Clementine shoot him without forcing it on her (not that I necessarily WANT her to shoot him, it's just bugging me and I want to know how that works)?
And please excuse my awful grammar. English is not my native language.