Director Kevin Smith on the air podcast Fatman beyond told that the story of Arthur Fleck in the Todd Phillips film “Joker“Originally had to end differently. And to explain how exactly, you have to resort to cruel spoilers.
In both cases, Arthur eventually ends up in a psychiatric hospital. In the film that he released, he runs away, leaving bloody traces, and orderlies are chasing after him: thus, it is assumed that he did away with his psychotherapist, or even not with him alone.
The alternative was much more deadly, and not only for the heroes of the film.
And we are shown exactly what: there is a flashback with the death of Thomas and Martha Wayne. And it is the Joker who kills them. And Bruce screams and cries. The Joker turns around to leave, then turns around, shrugs and shoots the child. Captions.
It is easy to understand that such an option for the finale would too clearly declare the alternative of the Joker universe. After all, the death of little Bruce would put an end to the appearance of Batman. It is clear why the creators decided to change the finale, making the story more ambiguous.