How does Cyrus Trask represent the theme of evil?

Fatherhood

Steinbeck creates two important father figures in the novel: Samuel Hamilton and Cyrus Trask. Both of these father-figures influence the protagonist, Adam Trask, and present him with paternal models for the choices he must make in his own life. Both Samuel and Cyrus are bearded, in the biblical patriarchal style.

Adam's father, Cyrus, commits the novel's original sin by lying about his Civil War record to advance himself politically and financially. Samuel, on the other hand, is the archetypical force for goodness - the good father to Cyrus' bad father. He exhibits enormous physical strength and capability, while Cyrus hobbles on one leg. Samuel is a symbol of life, of fertility: he cultivates barren soil, fathers nine children, and is associated with water imagery. He digs wells, is always washing, and delivers the twins, Aron and Cal.

Cyrus, on the other hand, is a negative force: a cruel, one-legged thief, Cyrus continually manipulates those around him. He is associated with disease and death, rather than fertility. He infects his religious wife with syphilis, causing her to commit suicide.