I think we should be a grown up Clementine. Maybe Lee's actions have an effect on Clementne's future. She is more of a ruthless survivor if Lee took wha he needed from the car and killed potential threats, and more compassionate and mercifull if Lee was.
This would be just a little blurb at the beginning of the game and changes some npc reaction dialouge. Nothing big enough to give the writers a headache with huge decision trees. There must also be a default history.