Well, he was basically doing that because he wanted to be hated. He slowly moved away from being hated pretty much when he started getting Kate (so season 3). Before that, he did show touches of humanity, he would just regress at other times. Plus, finally killing Real Sawyer helped as well.
It wasn't an overnight thing. They plotted it out fairly well.
It wasn't an overnight thing. They plotted it out fairly well.