Zombie Cliché Lookout:
The thing about redemption, especially once civilization has come to an end, is that it’s not easy. If you’ve betrayed your friends, you can bet that it’s going to take a hell of a lot to get back in their good graces. Heck, it might just be the death of you. Conversely, if you’ve got a guy in your group who’s just done something incredibly stupid and is now a hair away from getting kicked out, you can probably count on him to bend over backwards to make it right.
Unless of course they’re a badass loner who plays by their own rules, in which case all bets are off.