K.M. Weiland covers splitting the objective role of the Protagonist from the subjective point-of-view of the Main Character. She gets some things right and some things wrong, with the former outweighing the latter. The best most amazing part of her post is the giant cover photo of the Dramatica theory book, complete with generous attribution to Chris and Melanie. Never thought I would see the day when someone besides me would actually give credit to the people who started it all.
He [the Main Character] must be personally impacted by the protagonist and the main conflict.
This assumes that the Protagonist is also the Influence Character which isn't always the case. It is in Mad Max: Fury Road, The Lives of Others and The Shawshank Redemption, but it isn't in Casablanca nor Searching for Bobby Fisher.
I feel bad pointing this out as she fixes this mistake later in the comments, but for those who don't read comments, I submit the above.
Depending on your choice of main character/narrator, you have the potential to create interesting layers of juxtaposition and irony within your story. How different might Harper Lee’s To Kill a Mockingbird have been without the filter of Scout’s child eyes viewing her protagonist father’s actions?
Harper Lee uses a very clever technique to examine prejudice: objectively by looking at Atticus and the trial, and subjectively by looking from within Scout and her personal prejudice against Boo. Damn clever.
Stories with multiple POVs will allow you to show your protagonist both inside and out, but some protagonists may be better served only from the more objective outside perspective of a main character
There's more to this that is even more fascinating: the Main Character and Protagonist take two different views of the same inequity. Examine the example of To Kill a Mockingbird above: it's more than simply a matter of "better service", it's essential to our understanding of how to solve problems. We get to see the most appropriate way to deal with prejudice both from within and from without ourselves. That is something you can't do in real life.
K.M. refers to the Impact Character which is old terminology for what is now called the Influence Character. There is no perfect name for this essential part of story, but Influence is the less prescriptive. ↩︎