In Arthur Miller's Death of a Salesman, minor characters provide a thread of reality in sharp contrast with Willy's world of fantasy; they also highlight the theme of missed opportunities, and offer deeper insights into major characters.
Willy is a man living in the past, reliving former career success—well past the age of retirement: the days of making good money and being admired are gone...though Willy can't accept this. Willy is also a man who is certain that his son Biff, a former high school football star, should have been (and one day may be) an enormous success—except that Biff failed math in his senior year, did not graduate, lost his college scholarship, and has never been a success. Willy loses touch with this reality.
Bernard is an extremely important minor character. Charley is Willy's friend, and Bernard is Charley son. Bernard always seemed to know what needed to be done to achieve success. In high school, Bernard worried about Biff and his math grade, which at first seems to have been the cause of his "failure." But as the play goes on, the audience learns that failing math was only a stumbling block.
For Biff, the hardest parts of his life have been trying to find happiness—away from home; supporting and loving his mother, while having lost respect for his father—for since then, Biff has been lost.
Bernard, however, was always on the right track. In a flashback, Bernard shows himself to be a solid young man as he tries to share with Willy and Linda much-needed news concerning Biff.
BERNARD [entering on the run]: Where is he? If he doesn’t study!
WILLY [moving to the forestage, with great agitation]: You’ll give him the answers!
BERNARD: I do, but I can’t on a Regents! That’s a state exam! They’re liable to arrest me!
In Act Two, there is another flashback, showing the relationship between Biff and Bernard.
[Young Bernard rushes in...]
BERNARD: Oh, gee, I was afraid you left already!
WILLY: Why? What time is it?
BERNARD: It's half-past one!
WILLY: Well, come on, everybody! Ebbets Field next stop! Where's the pennants?...
BIFF [who has been lumbering up]: I want to go!
BERNARD: Biff, I'm carrying your helmet, ain't I?...Biff, you promised me...
Biff treats Bernard dismissively. Biff speaks "grandly" in response to Bernard's request. Bernard's presence allows the audience to understand young Biff better—he saw his life full of promise—and he was a little cocky. Yet years have passed, and it is clear that Bernard had much more going for him than the once-promising Biff.
The action returns to the present, and Willy meets Bernard at Charley's office. Bernard is described in the stage direction as...
...a quiet, earnest, but self-assured young man.
Willy asks Bernard to explain why Biff was never able to achieve success like Bernard. The younger man has no explanations, and hesitates to give Willy advice. Bernard becomes pivotally important as he asks Willy if he ever discouraged Biff from attending summer school. Bernard shares that Biff had every intention of making up his math class, until he went to Boston to visit Willy on a business trip: it was at that time that Biff discovered his father was having an affair.
Bernard represents opportunities (and lost opportunities) of youth—which he seized with both hands. Bernard's character drives the plot forward, and provides essential information about Biff and Willy. Miller uses this minor character to further develop two major characters.