Re: The Dark Knight Returns - if you were to do a sequel/prequel/spin off
^Best of luck to you. I'm actually working on the 1st revision of my first novel (with an editor in New York who's been in the biz for 30 years)... so I know how tough writing can be. People who aren't writers haven't a clue.
I think Neil Gaiman said it best, "You sit down at your keyboard and put one word after the other until it's done. It's that easy. And that hard."