@marquis: get past season 1. Eventually the zombies become less of a threat factor, especially individually or in small groups. Now it's about building and finding a community you can trust. The way they built the show in the last 2-3 seasons, you feel you're in their shoes to where everyone you meet, you become suspicious of. You'll think everyone has an agenda.
@dyager: I think that's what makes the show great. People do change, and in a society without rules where every day is a possible fight, it can play on you.
Every time the group found sanctuary, it fell apart, especially the prison. They setup a great life there that had the ability to let them raise families. When that sense of security in a world of uncertainty is lost and gained over and over, it has adverse effects on people. Some lose hope, some do things they wouldn't do in order to survive. Carol, Carl, Rick, Andrea, all are/were great examples of that.