Superheroes, as they're known today, originated with Superman in 1938, and have been present in comic books ever since. Until recently, however, superheroes were almost never seen in prose fiction -- just a few novelizations and media tie-ins. Now there's a lot of superhero prose being published. What changed? How do you write a good superhero story in words rather than pictures? What works in comic books that doesn't work in prose and vice versa?