Kennys story like Lees was a story of redemption. Kenny never got over the death of Shaun, blaming himself for it and believing his inaction in that death to be a contributing factor in Duck's death. The way he treated members of the group, what he did to Larry, the callous attitude to the woman in the street, all were signs of his de-humanization. He was becoming like one of the monsters, and I'm not talking about the walkers, from Crawford. I like to think in the end Kenny realised what he had become and regretted a good deal of the things he did and how he treated the people around him, especially Ben who he blamed for the exact thing Herchel blamed him for, and his sacrifice was a way of redeeming himself in the eyes of the group, Katjaa, and more importantly himself.
"All we need is one pin Rodney."