Biff Loman

 
" All right pal....I've been remiss. I know that, Mom. But now I'll stay, and I swear to you, I'll apply myself....you see...I don't fit in bussiness....I'll try, and I'll make good."
Pg 47

This a big step for Biff. He know that by making this promise, it means that he is officially entering the life style that he doesn't like. After he heard about Willy had been trying to kill himself, his reaction is to stay. I think it is not only because he doesn't want her mother to face all these alone. It is that he doesn't want his father to die. No matter how Willy had hurt him, he shows that he cares about his family. Even though whenever he talks to Willy, they end up fighting most of the time, he cannot just leave him alone. Biff is actually a very caring person.