Rupert -- like all of life's losers who build their identities and derive their self-worth from basking in the reflected glory of people more successful than they (in this case, by collecting celebrity autographs) -- doesn't have much going on in his life. He lives in his mother's basement in one of the outer boroughs of New York City, where he holds imaginary conversations with cardboard-cutouts of celebrities like Liza Minnelli and Jerry Langford (Jerry Lewis), the host of a wildly-popular, self-titled nightly TV talk show that can make or break new comedy talent. Of course, it's pure fantasy, one that seems galaxies away from the reality of Rupert's pathetic existence.
That is, until, fate lands him a seat in Jerry's limo after the show one night. Riding a few blocks from the studio to Jerry's apartment, Rupert takes the opportunity to pitch himself to Jerry as a potential guest for his show. In order to get rid of his personable but rather unbalanced passenger, Jerry tells Rupert to send a tape of his act to the show's producers for consideration. This chance encounter plunges Rupert into a wild fantasy in which he becomes convinced he and Jerry are best pals, and that his future as "the king of comedy" has been handed to him on a silver platter.
De Niro's performance as Pupkin strikes a masterful chord. He and Scorsese wisely avoid making him a caricature or an object of ridicule. Even when we want to laugh at his delusional behavior, ridiculous as it may be, there is a layer of real pain and sadness not deep beneath the surface. Scorsese only hints at Pupkin's past, and even what we see of his personal life is limited largely to his fantasies. His mother, for example, is only ever heard as a disembodied voice, shouting down into the basement for Rupert to go to bed or turn down his music as if he were still an adolescent boy. The most we ever learn about Rupert's childhood is, tellingly, through the anecdotes he delivers in his standup monologue, though even these -- at least one of which (involving his mother being dead for nine years) is directly contradictory to what we know -- are infused with a level of fantasy. What Rupert's jokes do reveal -- when we finally hear them -- is that he seems to use self-deprecating humor as a way of dealing with an unhappy childhood (through jokes about his abusive and alcoholic parents, bullying classmates and indifferent teachers). We get a further hint of this earlier in the film, when Rupert imagines his old high school principal publicly apologizing to him on television for the way he and the students treated Rupert.
Indeed, it seems that what Rupert wants more than anything in being famous is just to be loved and adored. Though he treats Jerry like a buddy and an old pal, it is conceivable that he could also see in him something of a father figure, someone who can give the affection and approval that Rupert has always lacked. But that would also imply that Rupert realizes he could learn something from Jerry. Instead, he seems to view Jerry purely opportunistically, as someone whose fame and fortune can rub off on him and who will get him to where he wants to be. Of course, Langford is hardly a perfect role model himself; you don't get to the top by being a nice guy. That said, Lewis and Scorsese are careful not to portray Langford merely as a belligerent jerk or egotistical bastard, which would undercut the character. Langford is clearly a hard-working and dedicated show business professional who has paid his dues to get where he is, but has become jaded by his experiences in dealing with hangers-on and phonies. If he is impatient or demanding, it is only because he expects of others what he expects of himself. Ultimately, he is portrayed neither as a monster or a towering genius but -- as Langford says of himself in one scene -- a human being.
In addition to his relationship with the celebrities he worships, Rupert is also incapable of real friendship with other people in his life, no doubt a result of his social awkwardness and also of his extreme narcissism (it quickly becomes clear that Rupert's favorite, indeed only, topic of conversation seems to be himself). He seems to have a kind of love-hate relationship with an even more unbalanced celebrity stalker named Masha (Sandra Bernhard, in a brilliant performance) -- though their relationship is never made clear, it doesn't seem to be sexual in any way, but it does seem to be co-dependent on often borderline sadistic behavior toward each other. Around his fellow autograph hounds, Rupert sees himself as superior, telling one of them that collecting is "not my whole life", suggesting that he views the others as pathetic, while his purpose in collecting is more noble. When he rekindles an acquaintance with Rita, an old high school crush, Rupert seems to only be capable of viewing her as another character in his life story that he's mapped out, going so far as to give her his own autograph as a gift, since it will no doubt be worth a lot of money someday, and fantasizing about the two of them being married on live television. Even in his fantasies about Jerry, Rupert frequently imagines Jerry groveling toward him (begging him to take over the show for a few weeks, and telling Rupert how envious he is of his genius) rather than imagining any kind of real friendship between the two of them.
Rupert's illusions about that friendship come crashing down when he takes Rita out to Langford's Long Island home, where -- he assures her -- Jerry has personally invited them to spend the weekend (he has, of course, done no such thing; the invitation was purely the product of Rupert's overheated imagination). When the pair show up unannounced, Jerry has to cut his golf game short to come home and deal with the intruders. Mortified, Rita apologizes and insists on leaving (but not before pocketing one of Jerry's knick-knacks as a memento). Rupert, however, insists Jerry has mis-treated them and makes veiled threats, whereupon Jerry has them both thrown out of the house. This is the breaking point for both men -- Jerry tells Rupert exactly what he thinks of him in no uncertain terms, and Rupert concocts an incredibly dangerous and foolish scheme to get his big break in show business that will have lasting consequences on the rest of his life.
It is revealing in this scene that when Rupert does get a glimpse of Jerry's private life, it does not turn out to be the glamorous atmosphere of schmoozing and hobnobbing with other celebrities that Rupert has no doubt envisioned. Instead, Jerry spends his Saturday relaxing with a game of golf and enjoying the peace and quiet of his home, enjoying the leisure time he has earned and re-charging his energy before another tireless week of performing. Jerry has to waste precious free time out of his weekend dealing with Rupert, who wants Jerry to drop what he's doing and listen to his tape, to which Jerry snaps, "I have a life" -- a life he has worked very hard to build for himself, and the kind of life Rupert feels entitled to just by wanting it.
Indeed, that is perhaps the ultimate tragedy of Rupert Pupkin. As his climactic standup act shows, he is not without some talent. But he is unwilling to work hard to achieve his goals. He is more interested in talking about being a comedian than ever actually going out and being one. Like so many wannabes, he waits on the sidelines for that "perfect opportunity" that may never come, rather than taking the bold first steps toward his goal, because he knows it can never live up to the results about which he he has fantasized many times. As Jerry tells Rupert during their first meeting, the comic timing and interplay that appears so natural and relaxed on his show is the result of years and years of hard work and practice, and that the old axiom happens to be true -- you have to start at the bottom. Similarly, Jerry's producer helpfully tells Rupert after listening to his tape that he has potential and should hone his act for a while on the nightclub circuit, where he can develop and perfect his material, before auditioning to appear on network TV. All sound advice, but not the easy answer Rupert is looking for.
Of course, in Rupert's case, he eventually does get the "perfect opportunity" he's been waiting for -- when he and Masha resort to kidnapping Jerry and holding him for ransom in exchange for a coveted guest shot on the show -- but by that point, it is clear that Rupert can no longer see the division between real life and fantasy, and indeed, by the end of the film, neither can the audience. Rupert's act is, surprisingly, not awful, and -- we are told -- that after serving a short stint in prison, during which time he has honed his comic material, he writes a best-selling book about his escapades (about to be turned into a major motion picture), and enjoys the fame and adulation he has always craved. Scorsese leaves us wondering how much, if any, of this is true. It doesn't matter. Either way, Rupert's success -- whether entirely the result of his delusional imagination or the result of a sated public willing to applaud anything put in front of it on television -- is an empty one.