The Batman that I loved growing up, the thing that Frank Miller did in 'The Dark Knight Returns,' is that he's so vulnerable and mortal in his 50s. That book was the first time I saw Batman as being really layered, human, and suffering, and worried that he wouldn't achieve what he wanted to achieve. Seeing him being obsessed and pathological.

There's an element of ego to writing the Riddler. You research a lot of things that you end up jettisoning as a writer, and Riddler was a lot of fun to get to have that sort of annoying know-it-all personality lording over the city. He's a lot of fun to write about.

I remember when I was in school I had this teacher give me this E.L. Doctorow quote: They asked him how much historical research he does for his books and he said, 'As little as possible.' So I try and adhere to that.

I've said before, I've always had difficulty with anxiety and depression. I've been on medication for it since I was about 18 years old, varying degrees of medication. I've had big ups and downs with it and very bad periods.