Joker is a heavy, mentally and emotionally challenging movie to watch.
This film focuses on the backstory of Joker, Batman's famous nemesis, presented and told in a dark narration.
In here, we will see Arthur Fleck, as a mentally ill person dreaming on becoming a successful comedian. But Arthur was going through though times in life; having a sick mother dependent on him, investigation of a crime, struggle at work the eventually losing it, and the cruelty of the society.
Despite being an installment to DC comics or movies, Joker is another story depicting the Marxist philosophy where there is a division in the society-- the upper class or capitalists (bourgeoisie) and the working class or wage-earners (proletariat). And this conflict in the contributed on how the film highlighted the mental health issue.
When Arthur's character was being established during the first part of the film, he was seen as a man who has positive thoughts though he has special needs, probably because he had someone to talk to and a support system. But when this support system failed him, adding to the conflicts he was encountering from his family history and the society, his character started to develop, including his mental health status. And this leads to Arthur becoming "the" Joker now.
A lot of different factors may test one's mental fitness. In this movie, we are taught on how social class, lies and abuse triggered Arthur's personality that caused him several mental conditions that defined his behavior.
Joker came out in time as just we have celebrated the World Mental Health Awareness Day last October 10. A happy face does not guarantee that one is mentally healthy. Sometimes, they are just putting a happy make up on their faces to mask the pain and the struggle one's personality is going through. In the movie, we learned how important it is to have someone to share our thoughts to and that the stigma on mentally ill person must be eradicated because they need us, they need help.
While comics and/or the Batman superhero was giving us heroic entertainment, here, we witness how tragic Joker's past was and his story was told to us also in a dark manner. Maybe, we are to expect also that the future Batman movies will be as dark as this? We will soon find out. :)