The Batman cleverly incorporates a part of the famous "I am vengeance" Batman line into its story, and a fan theory claims that this could be the first of a three-act character arc. With a solid box office and near-universal praise, The Batman getting a sequel announced was no surprise. While Matt Reeves had expressed his desire to make a film that could work on its own, the director will now have the opportunity to continue to develop this new, younger version of Bruce Wayne that he and Robert Pattinson created.
Contrary to what Christopher Nolan had done in Batman Begins, Matt Reeves chose to skip the Dark Knight origin story and placed audiences in Batman's second year in Gotham. However, that did not mean that this Batman still did not have a lot to learn. On the contrary, Robert Pattinson's Batman started the film acting as a symbol of revenge and violence - something that hurt what he was really trying to achieve. This is made clear during the Riddler's interrogation scene, in which the villain reveals that Batman was his inspiration to seek revenge on Gotham City. In the deleted Joker Arkham scene now revealed to the public, this is also evident, with the Joker making fun of Batman being scared of the idea that the Riddler was inspired by the vigilante.
The script element that best symbolizes how this Batman was walking the wrong path is the fact that he calls himself "vengeance", a direct callback to an iconic Batman line from Batman: The Animated Series that goes to say "(...), I am the night, I am Batman." While those last two parts are not said in the film, one fan theory (via Reddit) claims that "I am the night" and "I am Batman" will be the symbolic themes of The Batman 2 and The Batman 3, respectively, just like "I am vengeance" was the theme behind The Batman.
The "I am vengeance, I am the night, I am Batman" line originated from "Nothing to Fear", the tenth episode of Batman: The Animated Series season one. In the story, after being infected by Scarecrow's fear toxin, Batman starts having hallucinations in which his father, Thomas Wayne, says he is disappointed in what Bruce has become. In addition to the fear toxin, these visions were also a consequence of an old friend of Thomas Wayne's questioning Bruce and saying that Thomas would be ashamed of how the Wayne name was being used. -Collider