The film has a lot of unreliable characters. Like a lot of interactions he has with Sophie (Zazie Beetz did a good job with what little she was given. Her screen presence is so warm) are fake. His mom claims he is Thomas Wayne's son but Thomas Wayne says his mom is delusional.

He goes through her Arkham files and it seems like Thomas Wayne is telling the truth. But then later on we see him looking at a picture of his mom and on the back Thomas Wayne wrote a really sweet message which confirms an affair and further gives to the corruption commentary this film tried to aim for (or maybe was never aiming for. Who knows). It's possible T Wayne may have falsified reports and documents to save his ass. We will never know.

There is some good and some legit interesting stuff about this movie but it gets muddled in Todd Phillips's ego.

Don't forget Alfred who also seems to know about the Thomas and Penny affair.

he seems to be ripping headlines from the news and trying to talk about them in this movie. Conceal carry, social services being cut, oppression, corruption. Like there clearly is a lot going on here and Phillips wants to talk about it. But thing is, I feel like he never really does. It's mentioned and then onto the next scene. He wants to show us that he can make a mature film and while this film is more mature than his past films aesthetically, it's not really there thematically or in the text.

He wanted to show us so bad that he's the smart kid in class but he doesn't do what smart kids do: go in depth and have a central unifying thesis.

Well, like I said, it's told so squarely on Arthur's shoulders that it doesn't get much further than Arthur being unreliable as fuck and descending into madness more and more. If there was another character, like Batman lol, then you could measure it all against him. Like in The Dark Knight lol

Anyway, I think a movie completely focused on the Joker can work and I think this did. I never would've thought it would've been told 100% through his perspective, probably because I'm not used to it when it comes to this character, but still. I think Philips pulled it off.