Without going into immensely drawn out thoughts of how individuals with mental illness are viewed, examined, then shelved and basically forgotten other than becoming statistics. I think this movie was one of the greatest reimaginings of a live action DC comic book villain origin story ever on the big screen. It holds true to what, at least I always imagined, Gotham City to have been like in a real life scenario. As well as the trials and struggles that may lead to the mental hatred of those with undeserved power. It shows how fragile the human mind can be after a lifetime of abuse, neglect or being taken for granted and pushed away like they don't matter. For cinematic purposes, I truly hope that any and all DC films that come after this, keep up with this type of storytelling and takes The Batman to the next level where he has ALWAYS belonged. It's obvious Bruce Wayne also has severe mental illness due to trauma he has witnessed and/or experienced, same as Joker, but has simply chosen a different outlet or path.
( POTENTIAL SPOILER WARNING AHEAD)
Being presumed "brothers" by a mentally unstable outcast shunned, disregarded and pushed away by anyone in a seat of authority may shine a very bright light on the story behind the biggest comic book rivalry ever imagined. The feeling of hatred toward the boy who had been provided with everything and given every chance by a man who should have done the same for him. Whether it's the truth or just hallucinations as indicated. Joker is sure to know exactly who The Batman is when he finally arises. And so begins the fighting, unable to destroy one another fully because of a bond that Batman feels but doesn't know. Batman only blames Joker, and his actions, for being the breaking point of already unruly and unstable protesters, beginning the chaos. Ultimately this led to the lifelong mental trauma young Bruce endures by witnessing his parents gruesome murder. If The Batman stays true to this story line, I can't wait to finally see a truly Dark Batman story born from trauma enduced mental illness, focusing partially on the constant battle inside of himself. Fighting ultimately to not turn into the people he hunts and locks away. I hope this makes sense for the most part.