So why is Harley Quinn so popular with younger readers and viewers? Simple: she's something new for our time, rather than a dusty Cold War or World War II relic like the rest of the traditional superhero bunch.
Think about it. Just about every major superhero in comics and film—Superman, Batman, Spider-Man, Captain America, Wonder Woman—was created more than half a century ago. The fact that they are still relevant is amazing. But there's definitely room for new characters who represent modern times and ideas. Harley Quinn might be a psychopath, but she's also a modern woman: she fights for herself, she says what's on her mind, and she lives her own life. That resonates with younger audiences, particularly young women and girls, in a way that billionaire Tony Stark's struggles with capitalism or Captain America's longing for pre-war idealism just can't. For the superhero genre to stay relevant, Harley Quinn needs to lead the way.