1. Jean and Maria, in my opinion. Jean was a total b-word (not the good kind) for the entire movie and changed 180 degrees in a moment, which is as unrealistic as it possibly could be. Change always takes some time, so I believe her drastically made improvement was no more but an actress demand.
2. Tommy, a young police officer, in my opinion. He was inexperienced during the first inspection, after that he was brave enough to confront his boss in order to get a new partner, then he decided to help a guy because of his guilt. And one more time was too much for him so he just broke up and killed a poor fella. Didn't want to believe that coming, to be honest.