Injustice 2 Explained: What Does The Ending Really Mean?
7. Every Villian Is The Hero Of His Own Story
These words are uttered by Bruce Wayne in the court, after he describes why Superman must stay incarcerated, and they set the tone for the whole game.
Superman thought he was doing good when he went on a killing spree and murdered not only villains, but those that opposed him as well. Lured by Wonder Woman's vision that they'll rule the world together, Superman thought he was actually doing humanity a favor by taking it under his wing.
The same can be said of Lex Luthor, who also thought he was serving humanity by trying to stop Superman and contain his powers - just like in the Lex Luthor: Man of Steel series. He was killed by Superman in the first game. Now Luthor's name signifies a hero in this new reality, as he and Wayne have contributed millions of dollars to building a prison for meta-humans. The prison even bears Luthor's name.
At the end, when given the choice between either Superman or Batman, you're not making a choice between a hero and a villain, but two leaders with different visions of saving humanity.
The simplest difference is that Batman wants to abide by the rules, while Superman wants to set them.
This division also applies to the way both heroes will be remembered. After all, history is written by the victors, so the choice you make influences not only the present, but also the future.