Cal saw the confusion and helplessness on Aron’s face and felt his power, and it made him glad. He could outthink and outplan his brother. He was beginning to think he could do the same thing to his father. 

After Adam learns of Charles’s death in Chapter 30, Section 1, Cal speculates that his father will want to speak with Lee privately and vows to eavesdrop on their conversation. To prevent Aron from tattling, he threatens to blackmail him, an act which highlights Cal’s manipulative nature. This quotation emphasizes the satisfaction he gets from making others suffer and highlights the similarities he has to his mother, Cathy. By creating this parallel, Steinbeck hints at Cal’s capacity for evil.

He dredged up an old hatred to test himself, and he found the hatred gone. He wanted to serve his father, to give him some great gift, to perform some huge good task in honor of his father. 

In Chapter 39, Section 1, Adam picks Cal up from jail after the police catch him at a gambling house. The exchange that occurs between them afterwards is full of humility and honesty, and this moment leads Cal to view his father with a new reverence. Despite the loneliness and neglect he once felt as a result of Adam’s behavior, Cal’s devotion to his father grows even stronger. His deep love and desire to honor Adam with a gift makes Cal particularly reminiscent of Cain.

“I did it,” Cal cried. “I’m responsible for Aron’s death and for your sickness. I took him to Kate’s. I showed him his mother. That’s why he went away. I don’t want to do bad things—but I do them.” 

Cal’s confession to Adam in the novel’s final chapter highlights his desire to fight against the pull of evil. His decision to take Aron to meet Cathy was one rooted in anger and a desire for vengeance, but the guilt he feels in this moment suggests that he has not fully succumbed to his dark feelings. Instead, Cal exists in a morally ambiguous space between good and evil which offers him the opportunity to redeem himself. This confession is his first step toward redemption.