To the Gatsby anon: I did extensive research on the idea that Gatsby is actually a sociopath. I almost wrote a research essay on it but it was honestly for my own amusement so I didn't. I was however able to fill my copy of the book with evidence supporting it though, so I hope that gives you some inspiration! That book is filled with wonderful details that Fitzgerald alludes to but never comes out and says it.
Another idea for the Gatsby anon: the idea that each of the seven main characters (Nick, Gatsby, Daisy, Tom, Jordan, Myrtle, George) represents each one of the seven deadly sins and how that ties into the issues with morality in the 1920s
These are some interesting ideas. I don’t totally agree with all of them but literature would be boring if everyone had the same opinions, so if this works for you, have at it!