At the Dramatica Users Group meeting last night for Kingsman, Chris Huntley spoke about the relationship between the Main and Influence Character. Not so much about the [Relationship Story Throughline](/concepts/relationship-story- throughline), but rather the reason for the Influence Character in the first place.
To the Main Character, the Influence Character represents the path not taken. We tend to define the IC only in terms of their alternative approach towards solving problems or the one who influences and impacts everyone around them. Thinking of the IC as an example of what would have happened if the MC had built up different justifications prior to the story beginning opens the pathway to greater understanding.
In Braveheart, Robert the Bruce (Angus MacFaden) represents the path William Wallace would have taken had he not decided to take up arms against England.
In The Sixth Sense, Cole Seer (Haley Joel Osmet) represents the path Malcom Crowe (Bruce Willis) would have taken had he not decided to blind himself to what really happened that night in his bedroom.
In Kingsman: The Secret Service, Harry Hart (Colin Firth) represents the path Eggsy (Taron Egerton) would have taken had he not given up a future in the military to take care of his mum.
In Back to the Future, George McFly (Crispin Glover) represents the path Marty (Michael J. Fox) would have taken had he not decided to stand up against Principal Strickland (James Tolkan).
Defining the connection between Main and Influence Character in this way guarantees cohesion between the two Throughlines. It gives purpose to their presence within the narrative.