The cinematographer of JOKER says that Arthur didn’t kill Zazie Beetz’s character, or her daughter, in the movie. He says the director, Todd Phillips, said that he didn’t. I don’t think I believe him. If Arthur didn’t kill them, what were those screams and the police lights in the scene immediately following all about? If Arthur had left without harming his neighbor, she would have called the cops. It isn’t realistic to say she wouldn’t. And the cops would have come and immediately arrested Arthur and the rest of the movie wouldn’t have happened.
More than that, though, I think it is important that he did kill them. Why? Because if Arthur only kills the “bad guys,” people we, the audience, don’t mind him killing, the people who in some way or other deserve it, then he isn’t really a villain after all. He’s the Punisher. He’s at worst an antihero. No, for the Joker to be a villain, he *has* to pose a threat to innocent life. As much as he has the audience’s sympathy throughout the movie, there has to be a point wherein *he* becomes the *bad guy.*
If you’re making a monster movie and your monster only kills characters you don’t like, that’s cheating.