In the alternate future created in the classic Batman story The Dark Knight Returns, the world has become a very dark place and many of DC's most famous heroes have either met their ends or been twisted into unrecognizable versions of themselves. But Wonder Woman stands resolute. The Diana of Earth-31 (as The Dark Knight Returns' world was known in earlier DC continuity) is different from her counterpart in the main DC universe in many ways but is still recognizable as a powerful Amazon warrior, even though her relationship with Superman completely changed her destiny.
Diana does not actually appear in The Dark Knight Returns, but she is referenced, with Superman's internal monologue recounting how she returned to her Amazon home after superheroes were outlawed. The Earth-31 version of the character first appeared in the first sequel to The Dark Knight Returns, The Dark Knight Strikes Again, by Frank Miller and Lynn Varley. Along with Superman (with whom she shares a long-standing romance) and Captain Marvel, she is forced to work for Lex Luthor, who has covertly taken control of the United States.
When Brainiac invades Metropolis, the three of them fight back but Brainiac eventually forces Superman to stand down because he has the bottled city of Kandor hostage. Diana is by Captain Marvel's side as he dies. Eventually, Diana and Clark's daughter, Lara, who had been kept secret from the villains controlling the government, arrives to help her parents. With their daughter's existence exposed, Clark and Diana break away from Luthor and work with Batman's resistance to overthrow him. The Atom frees the Kandorians, who then destroy Brainiac, and the other heroes, including a returned Green Lantern, stop Lex's satellite attack before Hawkman and Hawkgirl's son kills him.
Diana also appeared alongside her family in the second sequel to The Dark Knight Returns, The Dark Knight III: The Master Race, by Miller, Brian Azzarello, Andy Kubert, Klaus Janson, and Brad Anderson. By the time the third series begins, Diana has given birth to Jonathan, her and Clark's second child, and her relationship with her daughter Lara, who starts to resent her isolated upbringing, becomes strained.
When the Kandorians are restored to their regular size it's revealed that a cult in the city led by extremists Baal and Quar had killed the other citizens and they begin conquering Earth. When Lara joined forces with the cultists Diana fought and defeated her in battle. Quar's forces later came for Jonathan, leading to a massive battle between the Kryptonians and Amazons, in which Diana played a major role. Quar threatening her brother also motivated Lara to change sides and she redeemed herself by pushing the tyrant into the sun.
Like the stories she appears in, the Earth-31 version of Diana is extremely controversial. Although Diana and Clark have been a romantic couple in several other continuities their relationship in Miller's franchise, especially the extreme nature of their sexual scenes has received particularly heavy criticism. Also derided was Diana's portrayal in All Star Batman and Robin, which Miller has confirmed is part of the continuity of his Dark Knight books.
In All Star Batman and Robin, Diana is portrayed not as the complex and loving character she usually is but as a hyper-militant soldier whose personality is reduced mostly to an intense hatred of men, even though she still has passionate feelings for Superman. This isn't unusual for Miller, whose handling of female characters across various works has drawn criticism. Miller's later work on the Batman franchise in particular was also known for having unusual portrayals of almost all the famous DC characters they featured, regardless of gender.