3. Dialogue
Bruce Wayne is naturally a very quiet character. Unlike Spider-Man, Batman fights his battles with grim determination. When you throw in a character like Robin or Batgirl however, Batman has something to talk about. In the comics, entire scenes of dialogue play out at the same time as the action. The story never has to slow down, but neither does the action. That kind of onscreen relationship is important and has been shown to be very effective in the most popular superhero movies like 2012's The Avengers.