Melanie Anne Phillips, co-creator of Dramatica, examines an alternative view of characters creating the plot as they are driven by choices and actions. In her article, she discusses how writers can operate in reverse and create characters if they already know their story. This is especially important in adaptations, or loose concepts. You’ve nailed the central theme and plot. You just need to populate your story with actions.
EXPECTED CHARACTERS: If you were writing the new Iron Man script, you need Tony Stark. Otherwise you wouldn’t have a movie. No Tony. No Iron Man. Pepper Potts (supporter) and Obadiah Stane (villain) are also expected characters.
USUAL CHARACTERS: You may include law enforcement/ military personnel and townsfolk who are impacted by Iron Man’s actions. They should be in the script, but can be inter-changeable or even omitted.
UNUSUAL CHARACTERS: These are characters that aren’t necessarily organic to your story, but add an unexpected dimension and subsequent interest to the plot. These include cameos and guest appearances. Imagine if Iron Man had a ballerina (who was a heart specialist) or a librarian (who doubled as an arms smuggler or insurgent)?
OUTLANDISH CHARACTERS: These evolved during brainstorming sessions and generally don’t serve the story engine, but rather enhance the creative process. Imagine Mary Poppins or King Nero appearing in Iron Man 7? How would they be integrated into the dramatic plot?
As an exercise, Melanie suggests picking a movie from a TV guide, one you’ve seen and one you haven’t. See how the characters have been described as well the logline of the film. Decide on expected, usual, unusual and outlandish characters and what direction they take your story in.