Happy Loman is Willy's youngest son and is often over shadowed by his older brother Biff and ignored by his parents. As a result of growing up in Biff's shadow, Happy was always striving for Willy's attention, but never really got it. This is shown when the young Happy is always telling his father
"I'm losing weight, you notice, Pop?"
The need for attention continues as an adult, but Willy and Linda continue to brush Happy off in much the same way they did when he was younger
Happy: "I'm gonna get married, Mom. I wanted to tell you."
Linda: "Go to sleep, dear."
Due to his being over shadowed by his elder brother Happy has grown up to be a stunted version of Willy's vision of the American Dream. Because of this it is difficult to identify with him; throughout the play he is presented as a one-dimensional character.
Although Happy grows up to become more financially successful than his older brother, he lacks even a spark of self-knowledge or capacity for self-realization. He does however share his father's capacity for self-delusion, declaring himself as the assistant buyer at his store, when, in reality, he is only one of the assistants to the assistant buyer.
Biff: "You big blow, are you the assistant buyer? You're one of the two assistants to the assistant, aren't you?"
Happy: Well I'm practically-
Biff: You're practically full of it!"