Remember, the Main Character and the Impact Character aren’t archetypes. They’re critical pieces of the story argument. If you want a Dramatica-approved story argument, you must have both of them, and their points-of-view need to interact in a relationship. It doesn’t matter what style of writing you’re attempting: movie, short story, rock opera, video game, whatever! If you don’t have an Overall Throughline, a Main Character Throughline, an Impact Character Throughline, and a Relationship Throughline, it can’t be a story.
As your stories get shorter, however, you have to make your Main Character and Impact Character arguments more succinct. I mean, I used this as an example elsewhere once:
“When I was in the army, I had to make some very tough choices. Our troop had captured an enemy woman, and my commanding officer wanted me to torture her for information. I knew this was wrong: she was a civilian, she was a prisoner of war, she deserved respect. But I also knew that if I disobeyed my superior officer, I could be severely punished. I struggled greatly with this problem, and the officer didn’t make it easy. But in the end, I refused to hurt her. I was punished pretty badly, but I know it was right.”
That story is less than 100 words long, but it’s a complete story. We have an Overall Throughline (Obtain information from the prisoner of war), a Main Character Throughline (the narrator’s Desire to do what is right), an Impact Character Throughline (the commanding officer’s threat of Future punishment), and a Relationship Throughline (the officer attempting to make the narrator Become willing to torture). Granted, it needs a lot more fleshing out (I don’t show how the Impact Character changes, I haven’t mentioned the Limit, I’ve skipped over most of the second and third acts), but it definitely demonstrates an argument.
Now, whether you need a protagonist and an antagonist is another story. Ideally, yes, you would. The Overall Throughline demands that you have a Goal that everyone is concerned with, and it would be helpful if you had a protagonist to pursue it. I can envision a story where we never really see the protagonist in action, though. Say, they’re a CEO in charge of completing a major bid, but we only see the action through the workers in the metaphorical trenches. Everyone is playing their part in helping this deal go through (the Reason accountant who works out the logistics, the Sidekick intern who always has a cup of coffee on hand, the Contagonist forms guy who’s always stopping work to make sure it’s being done “the right way”), but the CEO himself is just an idea without an actual presence. His perspective of Consider and Pursue is still around, but he’s not phsycially there.
Does that help enlighten you a little further? Yeah, it gets tricky when you start working with shorter media, but that’s the beauty of Dramatica: it works exactly the same no matter what kind of story you’re trying to tell.