In Arthur Miller's play, Biff and Happy are the two grown sons -- Biff is 34; Happy is 32 -- of Willy and Linda Loman. Neither can be said to have been successful in any particular endeavor, and Biff's having just moved back in with his family, where Happy remained ensconced, is testament to both sons' failures as adults. It is Biff, however, who is the catalyst for Willy's hopes and regrets, as it was Biff who once showed promise as a popular star athlete in school. And, as will be revealed, it was Biff's discovery of Willy's affair that served to undermine the little parental authority to which Willy still clung. Now, Biff has returned home again having failed in the "real" world of business. His dream of moving west and working on a ranch may eventually be realized, but his advancing age and aimless wanderings have defined him as an abject failure.
In contrast to his older brother, Happy is a more contented if similarly unaccomplished individual. While he works menial jobs, he has defined himself by his sexual exploits, evident when, early in the play, Willy returns from his latest business trip and inquires with Linda about his sons. Linda responds, "They’re sleeping. Happy took Biff on a date tonight." Happy is an avid womanizer whose lack of professional ambition is matched by that of his brother, but Happy lacks the eternal ennui that has come to define Biff. Not having been the brother to discover their father's infidelity, Happy remains more enamored of Willy's authoritarianism than the jaded Biff.
Miller regularly provided copious details regarding the backgrounds of his main characters, and his descriptive notes upon the introduction of Biff and Happy in Act I are useful in any essay comparing the two brothers:
"Biff is two years older than his brother Happy, well built, but in these days bears a worn air and seems less self-assured. He has succeeded less, and his dreams are stronger and less acceptable than Happy’s. Happy is tall, powerfully made. Sexuality is like a visible color on him, or a scent that many women have discovered. He, like his brother, is lost, but in a different way, for he has never allowed himself to turn his face toward defeat and is thus more confused and hard-skinned, although seemingly more content."
The character of Happy is less influential in Miller's narrative, although he is important for his insights into Willy's character, having remained in the Loman home while the older sibling had left for a time. Happy's aspirations for his future -- his current status as an assistant to a department store manager merely serves to illuminate the inadequacy of his ability to advance -- are realistic but expressed in self-destructive ways, as when he tells Biff about his propensity for sleeping with the women with whom he works who later marry higher-ranking corporate officials:
"Sure, the guy’s in line for the vice-presidency of the store. I don’t know what gets into me, maybe I just have an overdeveloped sense of competition or something, but I went and ruined her, and furthermore I can’t get rid of her. And he’s the third executive I’ve done that to. Isn’t that a crummy characteristic? And to top it all, I go to their weddings!"
While Happy may overcome his self-destructive impulses, though, Biff will find solace only in his willingness to leave the comforting if emotionally dysfunctional surroundings of home and venture west to work as a ranch-hand. Viewing Miller's play (or reading the script), one gets the impression that no such adventure is in the cards.