Though it's already established that Todd Phillips' Oscar-nominated Joker has no connection to the current slate of Warner Bros.'s DC Extended Universe, it doesn't stop fans from wondering how Joaquin Phoenix's Arthur Fleck, and his murderous machinations as the Joker, might fit in with that cinematic world. The DCEU's Harley Quinn, played by Margot Robbie in 2017's Suicide Squad and the upcoming Birds of Prey (and the Fantabulous Emancipation of One Harley Quinn), has a history with the Joker played by Jared Leto...but would she gel well with Phoenix's Fleck?