We have learned that Joaquin Phoenix's character will begin the film as Arthur Fleck before the series of events that drives him to become the Joker. As we told you before, Phillips' film will follow Fleck as he returns to a city on the brink. We believe that Fleck will return home to live with his aging (perhaps dying?) mother, Penny, in her apartment. It's here that he'll likely meet Sophie Dumond, the single-mother set to be played by Zazie Beetz, and begin his descent into madness described as the "exploration of a man disregarded by society [that] is not only a gritty character study, but also a broader cautionary tale."
We also know that Thomas Wayne will featured in the film, described as "cheesy, tanned" and rich-looking (remember this is from the Joker's POV), and that he will be in his 60s. Could Thomas Wayne's bastard become Bruce's lifelong enemy?
Fleck's mother was described as "very attractive in her youth", "obsessed with her former employer" and unable to believe "this is what her life has come to." Could Phillips' origin story be setting the stage for a deeper connection between Bruce and the Joker than we could have ever imagined? While it's just a theory, and a crazy one at that, it's possible that Penny once worked for the Waynes and that Thomas is the father of her son. Perhaps an interview with Wayne on the Murray Franklin show incites the dying Penny to spin the tale of her son's true parentage. Again, that's JUST A THEORY.
Source: http://thathashtagshow.com/2018/07/exclusive-new-details-dcs-joker-origin-story/
How hard is it to just take the flashback origin from Killing Joke and make it into a good movie? I do not like the sound of any of this - especially Batman having nothing to do with the Joker's origin.