Roy Cohn, a powerful conservative lawyer, is one of best villains ever to walk across a stage. Based on a real-life communist-hating figure, Kushner's Roy is unrepentantly vicious while still managing to be a complex and interesting character.
Over the course of the play, we see just how wicked Roy can be. First we learn that he's borrowed money from a client (in itself illegal) and he's trying to weasel out of repaying the loan.
When Roy offers to hook Joe up with a job in the Justice Department, we might think for a moment that he's a nice guy. We might say, "Aw, look, Roy might be a little rough around the edges, but here he is taking a young man under his wing." That bubble is swiftly popped, however, when we learn that Roy only wants to send Joe to Washington, DC, so that he can do unethical things to help keep Roy from getting disbarred.
In Roy's last scene of Millennium Approaches, we learn his biggest sin: he was responsible for the execution of Ethel Rosenberg. Roy was the Assistant US Attorney on this famous Cold War case in which the Ethel Rosenberg, her husband Julius, and others were accused of being Soviet spies. In the play, Roy brags about how he illegally coerced the judge into giving Ethel the death penalty. Roy is totally unrepentant about this and lists it as the thing he's most proud of. He brags to Joe:
I would have f--ing pulled the switch if they'd have let me. Why? Because I f--ing hate traitors. Because I f***ing hate communists. Was I legal? F--k legal. Am I a nice man? F--k nice. (3.5.19)
For more on Roy's villainy and a discussion of his role as antagonist, see "Character Roles."
If Roy were just mean to be mean, Kushner would probably be accused of turning this historical figure into a comic book super villain. This really isn't the case, though. Why? Probably because the play delves into the deeply conflicted nature of Roy's character. For one thing, Roy is a self-hating Jew.
Roy claims that one of the reasons the powers that be are out to disbar him is anti-Semitism. He says they think of him as "filthy little Jewish troll" (2.6.50). What is ironic about this is that Roy himself is one of the more anti-Semitic characters in the play. He calls the judge for Ethel Rosenberg's case a Yid, for example. And he almost seems to take pleasure in Ethel's execution because she's Jewish. At times, it's if Roy is at war with his own heritage.
We have to wonder, though, whether Roy has experienced a lot of discrimination in his life. Is his bias against his own heritage somehow a twisted reaction to the prejudice he's suffered? Whatever the case, it becomes more and more clear over the course of the play that Roy sees himself as a "Jewish troll" (2.6.50). You could interpret Roy's attraction to Joe as a hint of this. Joe is the poster boy for white Christian America, the very thing that self-loathing Roy secretly wants to be.
Besides being anti-Semitic, Roy also seems kind of homophobic. So, in typical Roy fashion, that must mean that he is gay. Just as he's disgusted by his fellow Jews, he has no respect for other gay men. He says to his doctor, Henry:
Homosexuals are not men who sleep with other men. Homosexuals are men who in fifteen years of trying cannot get a pissant antidiscrimination bill through City Council. Homosexuals are men who know nobody and who nobody knows. Who have zero clout. (1.9.3)
Roy refuses to be labeled a homosexual because he thinks that gay men have no power. And more than anything else, Roy loves power. He has plenty of it, and it's his most valuable possession. Roy argues that his refusal to be labeled a homosexual isn't just him playing word games or being hypocritical, it's just dealing with the reality of the world:
I have sex with men. But unlike nearly every other man of whom this is true, I bring the guy I'm screwing to the White House and President Reagan smiles at us and shakes his hand. [...] Roy Cohn is not a homosexual. Roy Cohn is heterosexual man, Henry, who f--ks around with guys. (3.9.37)
We have to wonder what Roy would've turned out like in a world where homosexuality was accepted. Would he have been the same bitter man if he'd been able to be open about his sexuality?