Now that Ralph is isolated, Jack sees a perfect opportunity to kill him. Jack orders the savage boys to start a forest fire and "to spread out in a line across the island" (232; ch.12) to find Ralph and torture him to death. Jack ends up creating absolute chaos by stealing from people, killing people and destroying an island with his power.
Like Jack, Archie also uses his power for violence. "Those Vigil assignments that had made him practically a legend at Trinity" "(9; ch.2) created a reputation that he was the guy with whom no one dared to mess. Archie was the one that picked the assignments and the people who were going to do it and no one wanted to be the person he picked to do it. Therefore, having a role as important as the assigner made everybody scared of him, which gave him power. Although Archie does create violence he usually isn't the one actually beating up people. Instead he relies on others to do the physical part for him. Later on in the novel, Archie tells Emile Janza, a bully in school, to beat up Jerry Renault, a freshman, for going against The Vigils' rules. Of course Emile didn't refuse because of what Archie could do to him with the power he has. "The blows rained upon mercy""(213; ch.31) and Jerry was so badly hurt that by the end "a black curtain (drew) over his eyes" (213; ch.31) and he passed out. Although Carter was officially the president, "everyone knew that the head of The Vigils was the assigner" (32; ch.5). Therefore, Archie Costello was the one behind all of the cruelty. He uses his power to make people beat up kids and in the end to create chaos.
Besides the fact that Archie and Jack both use their power violently, they also manipulate people. Throughout the whole novel Jack says and does smart things that he knows will manipulate the boys into fallowing him. First, Jack made it clear that he was the leader of the choir, proving to the boys that he has experience being a leader.