In the beginning of Death of a Salesman, what do we understand about Biff and Happy relationship?

Willy can't let go of idylic the American Dream that he has burried in his mind. This clouds his perception of the past. Biff certainly never measured up to Willy's expectations. There is antagonism between the two that is always boiling beneath the surface. Willy believes that Biff wishes to persue the same dream that he has. Willy sees Biff as an extension of himself persuing the American dream through bussiness (makeing lots of money!) While Biff would rather work on a ranch. The relationship is hence strained to say the least.

Over the years, Biff and Willy have come to a mutual antagonism. Willy is unable to let go of his commitment to the American Dream, and he places tremendous pressure on Biff to fulfill it for him. Biff feels a deep sense of inadequacy because Willy wants him to pursue a career that conflicts with his natural inclinations and instincts. He would rather work in the open air on a ranch than enter business and make a fortune, and he believes that Willy’s natural inclination is the same, like his father’s before him.

Happy's relationship with Willy consists of trying to be noticed by his father. He lives in the shadow of Biff's prowess in theft, girls and football. He spends his time trying to compensate for these things in the eyes of his father.