Batman Returns is a curious movie for many reasons. The references to German Expressionism. The small amount of Batman (and Batman's apparent willingness to kill). The overt sexuality. It's slightly shocking that studios let Tim Burton make this picture for the kiddies. While I can't pretend that I love Batman Returns, I have to admit that it's much more interesting than most Batman films.
The main characters of the film are the grotesques of Gotham and Burton gives them each a chance to shine. Villain Max Shreck (Christopher Walken) is a key figure in the city's political and ball scene, taunting Bruce Wayne (Michael Keaton) as he poisons the city's water supply and creates his own monsters in the form of Selina "Catwoman" Kyle and Oswald "the Penguin" Cobblepot. Kyle is a mild-mannered secretary who appears to be fed up with her dull life until Shreck pushes her over the edge literally and figuratively. Undergoing a quirky punk transformation, her personality is split between good girl Selina and the super-sexual Catwoman. But Catwoman's tight leather suit isn't the only thing that defines her as a rebel. While the Catwoman of The Dark Knight Rises reveals herself to have a heart of gold and ends up falling for Batman, this Catwoman prioritizes her independence at any cost. She seduces Bruce/Batman when she wants him, but when he forces her to choose between a peaceful, nonviolent life with him and revenge by killing Shreck, she chooses the latter.
But what about all of the references to German Expressionism? Burton lays it out fairly explicitly, from the city design to naming one character (who looks like Metropolis's mad inventor Rotwang) Max Shreck. Apart from the basic visual stimulation of that style, perhaps Burton is suggesting a kinship between Gotham and the dystopia of Metropolis. Here, however, Rotwang is already running the city and his mad genius unleashes the unpredictable Penguin and Catwoman.
* Though, he also is an abusive parent for his penguin army. They're clearly his family, yet he's willing to sacrifice them as part of his plan to destroy the city.
** Yes, I know, obviously half-bird/half-human beings and Catholics aren't the same.
The relatively contemporaneous Batman: The Animated Series contains episodes that outdo every single live-action Batman, helped by its wonderfully simple "Dark Deco" aesthetics.