Joker: Folie à Deux.
The first movie was not about Joker, it is about Arthur. Joker is the unfortunate identity he takes on as a result of the events of the first film. But at the end of the day, he was just a guy. He was delighted but bewildered at the people rallying behind him.

!Folie a Deux picks up is after the police inevitably apprehend Arthur. He is on medication, and speaking to a mental health professional regularly. He doesn't want to be Joker, but everyone around him expects him to be. The tragedy of the ending is that Arthur rejects the love and admiration he has earned, knowing it will not redeem him to the people who hate and fear him now. He chooses to be completely alone and powerless to stop hurting people.!<

As far as the musical numbers went, they were infrequent and clearly a representation of the connection between Arthur and Lee. There was at least one scene where we view Arthur from the perspective of onlookers after he finished singing and dancing, but all they saw was him staring at a TV or something. I always felt like the songs added to character development, but even if they weren't your thing they were brief and heavily outweighed by scenes with just dialogue.