Stylistically and tonally, the movie will be taking inspiration from Martin Scorsese classics Taxi Driver and The King of Comedy, and it’s not entirely clear how Batman will be involved.
Rather than being a part of the DC Extended Universe – where the Clown Prince of Crime is played by Jared Leto – this Joker movie will be an “elseworld” story that tells an origin story for the titular psychopath.
That being said, if Thomas Wayne is a significant living character in the story, that means it must be set when Bruce Wayne is just a child, meaning that the Caped Crusader may not have a part in the expected villainous transformation, as he classically has in the comics.