He's Shocked When He Finds Out The Truth - Tumblr Posts
So I saw this video of the Joker visiting Fawcett City and at the end he goes to a kids birthday party. Captain Marvel shows up before anything bad happens and defeats the Joker.
And there's this idea that Lex Luthor also visits Fawcett City because he thinks Captain Marvel is Kryptonian but gets his ass handed to him when Cap isn't affected by the kryptonite.
This got me thinking what if a bunch of different villains come to Fawcett City and are defeated then spend a night in jail. Inside the jail there's a "wall of shame" Cap made to discourage people from doing bad things and has a lot of pictures of people.
One day the league comes to Fawcett City and they see their villain on the "wall of shame", villains that are incredibly dangerous but Captain Marvel is just posing with a peace sign and a smile in the photos, the village look like they're having a terrible time.
Captain Marvel has no idea these are the dangerous villains the Justice League keeps talking about in meetings, he just thinks they're random bad guys.