Emerson: We sometimes talk about plays we'd like to do together. That shows how our minds work.

I shot a few scenes with her on "Person of Interest," which was a great pleasure. We'd never done TV work together.

CNN: What about a guest spot on "True Blood"?

Emerson: I'd be happy to do it, but I don't think it's ever going to happen. I can't go on there and play anything sinister because I've kind of done that. I guess I could play an innocent. I've said I'd be happy to play a humble human who gets torn apart by supernatural beings.

The characters I like on that show are the most ancient ones. I like Godric. I like thinking about how he looks like he's 19 but he's 2000 years old.

CNN: And what was it like voicing the Joker in the "Dark Knight Returns" DVD movie?

Emerson: If I knew how significant it was to play that role in that franchise, I think I would have been terrified when I took it. I must have been busy or distracted, because I went in there carefree. I had not seen these recent big screen "Batmans." That's probably a blessing. Later when I saw Heath Ledger, I thought "Oh, God. If I'd have seen this, I might not have done it." As it was, my only role model was Cesar Romero, and I thought, surely I can do as well as Cesar Romero.

CNN: Did you get to laugh?

Emerson: I did. It was a chance not to be repressed or contained. All the shows I do, it's all about keeping a lid on it or staying small. When you play the Joker, the sky's the limit. You can turn that thing up to 11.

I know it's a franchise where people have very high expectations and loyalties to whomever has played before, so I hope they'll accept me.