The first film I remember seeing Robert Downey Jr. in was Weird Science, where he played a douchebag boyfriend named Ian. In a film that was itself an uneven combination of elements sweet and profane, he found the right balance to make the guy a good old fashioned jerk and a little bit human at the same time. Since then, of course, he's gone on to star in imminently more sophisticated roles in prestigious movies for distinguished directors. But that combination of mischief and vulnerability has always been key to the success of his most memorable or effective performances; and moreover, the fact that he's been able to maintain that balance so successfully so many times is the main reason that it's so tough to decide which of the roles in his storied, up-and-down career might have been the very best.
With the possible exception of John Travolta, no actor in the modern era has staged a more dramatic career comeback than Downey. This is a guy who started his career as an ancillary member of the Brat Pack in the 1980s, became as famous for his off screen antics as on, and subsequently became a performer who seemed permanently, alternately destined to win a deluge of awards or wind up as another casualty of Hollywood excess. He spent a few years in the early 1990s trying to be a straightforward romantic lead, and made a couple of movies, including Heart and Souls and Chances Are, which showcased his good looks and irresistible charisma. But his turns in films like Less Than Zero and Chaplin hinted at the wealth of talent he kept hidden in these more conventional roles, not to mention the darkness of a lifestyle that didn't always resemble the sunny disposition of the characters he played.
I really think it may not have been until he played Wayne Gale in Oliver Stone's Natural Born Killers that he sort of took the door off of its hinges and kind of let all of his collective talent loose. Alternately shrewd and desperate, Gale was a suitably self-aggrandizing match for Mickey and Mallory Knox, and showed that the actor was unafraid to be disliked by audiences, and differently than when he played a real, complex figure like Chaplin, whom he channeled effortlessly but in a film that felt more readily familiar thanks to its biopic structure.
But it would be another five years before Downey would find his best role, as an equally unscrupulous but decidedly more human book editor Terry Crabtree in Wonder Boys. The film itself was virtually ignored by audiences when it was released in theaters, although Michael Douglas was still a star and Tobey Maguire a real up-and-comer, and Downey's performance – given at a time when his star had faded and supporting roles were largely his bread and butter – that sort of defined the film's overall understated, overlooked, but undeniable appeal.
It's not just that Crabtree seems to contain so many personality quirks that feels like a part of Downey's wheelhouse, although he does: he's charming, relentless, dubiously motivated, and always hustling, whether he's trying to coax a long-gestating book from his client or seducing a confused college student. It's that Downey is capable of combining the altruistic and the predatory, the benevolent and the sinister, into one believable, compelling, and yes, even sympathetic package.
Crabtree often feels like a bottom-feeder, the kind of editor who would steal his client's book in the night if he could get away with it, but Downey gives him a certain sort of humanity that makes him more than the sum of a series of always-be-closing clichés. And when he does finally seduce that confused college kid, he seems sincere, both in the sense that he's interested and that he wants the kid to be happy, too.
Of course, he's done some wonderful work since then in increasingly big parts, some of which were pure star turns (Iron Man, Sherlock Holmes), and others acting showcases (Zodiac, Tropic Thunder). But whether he's a dude playing a dude disguised as another dude or just himself, there's both a real talent and a star quality that can't be denied, no matter how big or small the part.