Willy casts a significant shadow and effect on his wife, children, and friend. Willy's effect on Charley is to represent everything that Charley knows is not right. Charley understands that the path he must take is one that is about as opposite as the one that Willy takes. Willy's effect on Charley is also financial, in that Charley has to loan him money every week as his only sustainable means of income. Charley and Willy argue and their disagreements revolve around one world view being advocated in the face of another. Charley realizes that Willy might not have much in way of respect for him. Yet, Charley understands that Willy is lost in his own dreams. The effect this has on Charley is to endure whatever insults and disrespect that Willy might impose upon him. Charley knows that what he is doing with his life is more creative and substantive than anything Willy is doing. Willy's lack of civility to Charley does not cause him to repudiate his own being in the world. Rather, Charley clearly understands the validation in his own being through Willy's failures in his.
Willy's impact on his children is representation of the absent parent. Biff embodies this fully in terms of his anger. Willy's effect on Biff is the very embodiment of what it means to be a failure. Biff recognizes that there was a point where he had talent and had the makings of "being something." Yet, Willy's effect on him is that he recognizes the convergent experience of failure in his own life and in what he sees in his father's. Willy's effect on Biff is meaningful in terms of his infidelities and the fact that Willy never took an active role in raising his child. Biff realizes that the effect of failure in as many ways as possible is one of the most profound effects that father has on son. Willy's effect on Happy is to cast in him the same pursuit of illusory dreams and unrealistic expectations that help to fill a void in his life. Happy's own emptiness and hollow pursuits give way to living out his father's when Willy dies:
"I'm gonna show you and everybody else that Willy Loman did not die in vain. He had a good dream. It's the only dream you can have—to come out number-one man. He fought it out here, and this is where I'm gonna win it for him."
One can see that Willy's effect on his children is significant. Biff recognizes the failures of his own father and himself as a result, while Happy seems to resurrect the same quest of futility in order to compensate for his own shortcomings.
Interestingly enough, I think that a case can be made that Willy's effect on Linda was to make her an even stronger force of redemption. While Willy does so much to damage so many around him and generate a corrosive effect upon so many, Linda never seems to waver in her commitment to her husband. She recognizes that her husband is absent both physically and emotionally. Yet, she is the continual force of redemption. While Willy brings so much from the real world and from his own tortured subjectivity upon her, almost creating the propensity for a negative effect, Linda does not take the form of this world around her. Linda repels Willy's effects and seeks to make positive that which is negative. While the world is harsh to her husband and thus helps to feed his harshness towards her, Linda does not waver in representing that which is good and honorable. In this regard, Willy's effect on her is where condemnation turns into salvation.