How is Jack different in Chapter 3 from how he was before?

In Chapter Three, we see Jack at ease in his surroundings. His place as leader of the hunters is firm and accepted. He thwarts Ralph by telling him he's in charge of the hunters, thus, Ralph needs to be stronger in communicating what he wants from the boys that he is in charge of. Jack has become confrontational, self-confident, and also obsessive in his own goal..... to kill and provide meat.