With salt air biting at his face, he turned and glanced at Edwin. The elder eyed him back with a dull stare. Anger welled up inside Cole. He hated that stupid stare. Pretending to aim toward the waves, he spit so the wind would catch the thick saliva and carry it back. (1.11)
Edwin and Garvey are here to help Cole, but all he wants to do is hurt them. He can't attack Edwin, though, so he does something equally disrespectful instead: He spits at him and pretends that it's an accident.
Cole jumped on him again and started smashing his head against the sidewalk. It took six other students to finally pull him away. By then, Peter was cowering on the blood-smeared sidewalk, sobbing. Cole laughed and spit at him even as he was held back. Nobody crossed Cole Matthews and got away with it. (1.21)
Cole isn't being punished for some small infraction—he's definitely a dangerous kid. The way that he attacked Peter Driscal was violent enough that he's looking at some serious jail time…
Cole's father turned around to face her. "You mind your own business or I'll use this thing on you." (6.49-50)
Cole hasn't pulled his violent ways out of thin air. The reason that he sees violence as the only option is because he's grown up in an abusive household—his father beats him up, so he beats other people up.
"Peter, would you like to tell us what you think would make things better again?"
Peter bit at his lip before speaking in a struggling, slurred voice. "I think someone should smash Cole's head against a sidewalk so he knows how it feels." (6.20-21)
In hurting Peter so much, Cole has set in motion another cycle of violence. Now Peter Driscal—who previously lived a normal life—is filled with anger and the desire for bloody revenge.
Cole stared down at his chest. The bear's claws had raked him open. His shredded shirt exposed gashes with long strips of flesh missing. One of the gulls squawked as it stole a stringy piece of meat and skin from another gull. Cole realized the gulls were fighting over bits of his own torn flesh. (8.14)
So much for bragging that he's not scared of any other people or animals. After being attacked by Spirit Bear, Cole finds out that he's pretty helpless—even seagulls are pecking at him and hurting him.
He wanted to throw up that anger like bad food and be rid of it forever. He turned to face the tree he had threatened earlier. Again he lunged toward the tree, only this time he let his fists strike the trunk. With each lunge, he struck the tree harder, ignoring the pain. (23.25)
When Cole finally does the dance of anger, he doesn't hold back. He attacks a tree and punches it until his hands are bleeding because he wants to let go of his violent tendencies once and for all. He wants to get it out of his system.
"I never told him he was worthless," Cole argued.
"Smashing his head on a sidewalk is a funny way of telling Peter he's valuable." (23.41-42)
All this time, Cole's had a hard time understanding exactly how his actions have impacted Peter's life. When he hears about Peter's suicide attempt, he realizes that beating the kid up has serious long-term consequences.
All the while, in the back of his mind, he knew he was a fool for even considering such a thing. No person in his right mind would ever go to an island in Alaska to be alone with someone who had beaten him senseless. (25.18)
The sheer violence and remorselessness of Cole's initial crime is going to make it hard for him to befriend and apologize to Peter Driscal. After all, the kid is scared senseless around Cole—and for good reason.
Three days later, while Cole was cooking lunch in the fire pit, a rock struck the ground only feet away. Cole turned to find Peter beside the shore, pitching stones into the water as if nothing had happened. Cole looked at the stone that had almost hit him and realized his hands were clenched into fists. (26.81)
Cole has let go of his anger (to the best of his ability) and tries not to act on any violent thoughts that enter his mind—but his crime has already changed his victim. Now Peter is the one who needs to express his rage in acts of violence.
As the blows pummeled him, Cole's own anger smoldered. He grabbed deep breaths. He would not get angry. Not now. As he tried to back away, he stumbled and fell. Peter was on him instantly, hitting and yelling. All Cole could do was curl his knees up to his chest and try to cover his face. (28.35)
Even though Peter is beating Cole up and telling him to fight back, he refuses to engage. He knows that this is part of his penance: He has to let Peter work out his anger and rage without fighting back.