Surprised no one just went with The Red and the Black.
Joker, through his use of frequent allusions, has really shown himself to be fairly knowledgeable of film, theatre, and literature. He's done Pagliacci in comics and TV, he's made Hamlet allusions, Hot Time in the Old Town in the '89 movie, Life is Like a Mountain Railroad in Last Laugh. I find that sort of funny. Between gutting people and torturing children he must sit a lot with a good book or those nights where he just stays in and Frank Capras it all evening. Lotsa bluegrass and ragtime on the madman's ipod.
Also, I really didn't need "redheaded women buck like goats" and the Joker conflated in my head. That's leaving scars, thank you.