The two leading men who have popped up in the most Martin Scorsese movies have been Robert DeNiro and Leonardo DiCaprio. Both actors seem to be drawn to a specific type of role – self destructive, intense, suffering. But rewatching King of Comedy, it struck me that one of the bigger differences between the DeNiro movies and the DiCaprio ones is that the DeNiro movies are much more ambiguous about how we were supposed to feel about these characters.
King of Comedy is about a would be stand up named Rupert Pupkin played by DeNiro who dreams of making it big in show-biz. When he's brushed off by a famous talk-show host, he kidnaps the host and holds him hostage with only one ransom demand: Pupkin's routine has to be played on the air. As the movie unspools it's unclear how we're supposed to feel about Pupkin; it's clear that he's deranged and unprofessional, but Scorsese and DeNiro – both of whom also started as outsiders and had big dreams of their own – clearly feel some sympathy for him, and the hints we get at his backstory suggest a tragic upbringing that would explain his need for adoration even if it doesn't excuse his great lengths to get it. At the end of the movie, Pupkin is rewarded with a book deal for his crime, justifying his decision to commit the crime entirely, further muddying the waters.
Taxi Driver has a similar ending to King of Comedy. In Taxi Driver DeNiro's character Travis Bickle is a violent misanthrope who almost kills a politician (which would have gotten him scorned) but ends up killing a pimp (which garners him public adoration for 'cleaning up the streets'.) Where Scorsese and DeNiro stand on the ethics of Bickle's murder spree is complicated to parse, both because the audience knows how ironic the triumphant news stories are, but also because the last scene of the film is incredibly ambiguous.
Finally, the same sort of through line can be seen in Raging Bull, where Jake La Motta becomes world champ in a brutal sport but never manages to leave the brutality in the ring. You want to respect him, but he's so incredibly cruel to his wife and his brother that he often seems like a man possessed by an evil demon. Still, he knows he's wrong, and the scenes where he literally beats himself up over his own failures makes it clear that on some basic level he can't control how brutish he is. All of these men are coin-tosses: on the right day they could be someone you would empathize with, but other times they seem like monsters.
In contrast, the inner confusion of DiCaprio's characters tends to be a little more clear-cut. The Wolf of Wall Street contains nuance and irony, but it's not really about the Jordan Belfort character that DiCaprio plays. No, Belfort is clearly a selfish asshole who cares for no one other than himself, and anyone who thought that he was being glorified just because he was allowed to be such an entertaining character is missing the point. The complicated ironies of that movie are about the system around Belfort, and what capitalism rewards and what it punishes.
DiCaprio's other characters are similarly well defined. The detective he plays in Shutter Island means well, but is revealed to be undeniably nutso and dangerous. His characters in the Departed and Gangs of New York have problems deciding on what the right course of action to take is, and they sometimes misstep or even flirt with making bad decisions, but they have a central core of honesty that they generally keep in tact even as they are pretending to be someone more violent than they really are. All of them put on appearances, but once you sort the wheat from the chaff you can get a good handle on what they really are.
Although there are a lot of ways to break down the differences between those two styles, for me the biggest difference is that when the DiCaprio style fails to reach it's ambitions, it doesn't entirely collapse - it just becomes a well-made genre movie. (Shutter Island isn't that great from a “this was made by a real auteur” perspective, but from the “this is a horror movie” perspective it's not bad.) In contrast, when the DeNiro version fails, the contradictory ideas don't set up poles for a debate, they create a muddle where nothing is said clearly at all. In many ways I think the DeNiro movies were going for something that's more ambitious, but the risk for failure was also higher.
King of Comedy is a good example of that. There's something frustrating about it's confused perspective. There's a thin line between creating ambiguity and undermining yourself, and I think it comes closer to undermining itself because it sets itself up as a morality play and then it doesn't stick the landing on the moral. But then again, maybe that frustration was the whole point; Scorsese and DeNiro obviously hated easy answers, so maybe the real joke of King of Comedy is on me.