Biff used to look up to his father before he found out about his dads affair. After that he lost faith in the american dream (American dream, having a lot of money, fame and so on) and therefore did what he wanted. Biff became a famer which was his strenght to steer away from the temptation of the American dream.
Previous to the affair, when Biff did look up to his father, Biff tried hard at sports and being popular at school because he thought that was what the dream was about.
His realtionship to every one sets him a side from his family - although Happy wasn't Willy's favorite son, Happy still went on to try and follow in hie fathers footsteps, where as Biff didn't.
In the play "The Death of a Salesman" Biff Lowman is Willy's favorite son. When Biff was growing up Willy backed him and covered for him. Biff was a good athlete so Willy lived the dreams of lost youth through Biff.
Willy has placed so many dreams on Biff's success that Biff begins to believe he is above others. When he ventures off into the real world he finds that his lifestyle and manipulations to make a quick buck are just dreams. He loses faith in himself and becomes a drunk. He even ends up on the street ad gets arrested.
Biff returns home to visit his parents and brother, Happy. The family live in a world of lies and half truths. Willy still believes his son is above him and Happy. Biff and Willy have a strained relationship. Biff had caught his mother with another woman in a hotel room. Since then their relationship has been strained.
Biff does not like the way that his father talks to his mother. He is worried about his father when he sees that he is mentally deteriorating. Of all the members in the small family, Biff is the one who finally faces up to the truth about their lives and his own self. By speaking the truth, he begins to heal himself.