An earlier released character description lists Sophie Dumond as:
Supporting female (27-34) to play African American or to play Latina. Not beautiful, has a hardness to her, a single mother living on the Lower East Side, doing the best she can, trying to make ends meet; worn out by the grind of the city. She understands how the system is stacked against her and the people in her community, how unjust it all is for them. She’s just trying to catch a break.
Sophie Dumond will be the love interest of Joaquin Phoenix‘s character, who eventually becomes The Joker, whose real name will reportedly be Arthur Fleck before his transformation.
This movie may or may not borrow from the story that is about as close to a definitive origin for the Clown Prince of Crime, ‘The Killing Joke‘ by Alan Moore and Dave Gibbons. In that story, a struggling stand-up comedian gets embroiled in organized crime after his wife gets pregnant. But on the night of his big heist, he discovers his wife dead after being electrocuted in the bathtub but is forced to go through with the robbery at the Ace Chemical Plant. However, during the caper, he is shot and falls into a vat of chemicals that transforms his appearance, giving him chalk white skin, green hair and red lips. After the shock of his wife and unborn child’s deaths, this trauma is too much and drives him insane.
Whether or not the Todd Phillips movie follows this plotline, it does appear that Arthur Fleck has some connection to the entertainment industry as Robert De Niro‘s character is believed to be a talk show host named Murray Franklin, who plays an important role in Arthur’s development.
Her casting has not been confirmed, but Frances Conroy is reportedly in negotiations to play The Joker’s mother, Penny. (Wait a second… like the giant penny in the Batcave? Is that intentional or a coincidence?)
‘Joker’ is scheduled for release on October 4, 2019, and is expected to begin production in September. It is not connected to the mainstream DC movie universe, in which Jared Leto plays The Joker.
Source: That Hashtag Show