The last character you really hated

[Ms. Marvel]

I get what Reece is saying. I love the Joker and that piece of shit rapes women.(Among other heinous acts) If the Joker was a real person, I would surely hate him, but as a fictional character, I love him. I think that's all that he means, its not something that's 'on you', as if to say you are a bad person if you don't hate villains. Some people can just easily separate the two from fiction and reality, so instead of hating an immoral fictional character, you root for them, even though you'd call for the death penalty on a real person of the same traits/actions in reality.