There are two story lines in every complete story, and you can either run them in parallel or you can hinge them together to form a dramatic triangle.
The first story line is the overall story that follows the effort of the protagonist to achieve a goal in which all the characters are involved.
The second story line is the personal story that follows the struggles of the main character to deal with a personal issue.
When you keep these two story lines separate and parallel, each advances on their own, and yet they still reflect each other.
For example, in the classic book (and the movie adaptation) of To Kill a Mockingbird, the overall story is about Atticus (the lawyer trying to get a black man a fair trial in the 1930s South) who is the protagonist.
But in the personal story we see things through the eyes of Atticus’ young daughter, Scout, who is personally dealing with her fear of the local boogeyman, “Boo” Radley – a mentally challenged member of a family down the street who is never seen and only known by rumor.
In the end, we learn about prejudice externally through what Atticus does, and we learn about prejudice personally through Scout’s prejudgment about Boo, until she is forced to change her mind about him when she comes to know him for who he really is – a caring protector who has actually saved her from others who would do her harm.
If Atticus were the main character, we would simply stand in the shoes of the fellow battling prejudice and feel righteous. But by standing in Scout’s shoes, we buy into her belief in the rumors about Boo, and learn how easy it is to be prejudiced whenever we base our opinions on what we hear, not what we see for ourselves.
In this example in which Atticus is the protagonist, the antagonist is the father of the white girl the black man is accused of raping, who wants the defendant lynched without a trial.
In the personal line, Scout is the main character and Boo himself is the influence character who has been leaving gifts for scout and protecting her all along the way, providing all the clues necessary for her to ultimately re-evaluate him.
Just as the antagonist fights against the protagonist, the influence character pressures the main character to change his or her beliefs.
In To Kill A Mockingbird, keeping both story lines separate has some advantages. For one thing, since the audience identifies with the Main Character, we aren’t standing in Atticus’ shoes feeling all self-righteous about fighting against prejudice. Rather, we stand in Scout’s shoes and learn how easy it is to become prejudice whenever we rely on rumor and other people’s opinions, rather than learning the truth for ourselves.
But, keeping the two story lines separate is a very complex form of structure and isn’t really need for most stories. It requires four special characters: protagonist vs. antagonist and main character vs. influence character.
A simpler alternative is to have both storylines occur between just two characters: a hero and a villain. A hero is a protagonist who is also the main character, and a villain is an antagonist who is also the influence character.
So, a hero is not only the person trying to achieve the goal, but is also the audience position in the story and the one who is grappling with challenges to their belief system. And, a villain is not only the person trying to prevent the goal from being achieved, but is also the person challenging the main character’s belief system.
While this sounds very efficient in concept, it is also very dangerous. Each of these story lines needs to be fully explored with no gaps or holes if the reader or audience is to buy into it. But, as an author, it is very easy to get so wrapped up in the action or the passion of one of the stories that you skip over parts of the other one in your eagerness to push ahead with the exciting one of the moment.
As a result, there can be significant gaps in each of the two – gaps that undermine the believability of the overall story and make the personal story seem unrealistic and contrived.
The more this happens, the more the complete story begins to feel like a melodrama, where characters jump from one frame of mind to another without motivation, and where events happen after other events without any understanding of why.
Fortunately, there is a better way to arrange the two story lines so each is clearly seen and fully developed, and yet they are tied together in a manner that strengthens the story as a whole. That method is the Dramatic Triangle.
A Dramatic Triangle hinges both story lines together around one character and anchors the other two ends on two different characters. The most common way to do this is to create a hero who is both protagonist and main character, with a separate antagonist and a separate influence character.
In this arrangement, the hero fights against the antagonist in the overall story, and has to defend his belief system against the influence character in the personal story.
A common example would be a hero who has a love interest, who is his influence character. She loves him because of his moral outlook. But, the hero is fighting against the antagonist who, seeing the love interest as a weakness of the hero, kidnaps her.
Now, the hero is torn between two things. To free his love interest, he must adopt the immoral tactics of the antagonist. If he does, he will save her, but lose her love. Tough choice, and the stuff great stories are made of!
A variation of this is for the protagonist to also be the influence character, rather than the main character. Then, he would be fighting against the antagonist in the overall story, but he would also be trying to change the beliefs of the main character, who is the third corner of the triangle.
In this arrangement, we would not be seeing things through the eyes of the protagonist, but through the eyes of the main character. We stand in the shoes of the main character and watch the protagonist/influence character, but be personally challenged to change our beliefs by him.
This arrangement was used in the movie, Witness, with Harrison Ford as a police detective and Kelly McGillis as Rachel, a young Amish mother with a son who has witnessed a murder when they were traveling.
Ford is the protagonist trying to protect the child, and the murderer is the antagonist trying to kill the child. We see the story through Rachel’s eyes, making her the main character, and Ford is the influence character as he is trying to convince Rachel to leave her Amish community and go with him into the larger world.
This still satisfies the needs of having the two story lines, but provides an unusual reader/audience position in the story at large.
But there are other ways to hinge the two stories together as well. In one version, the antagonist might be the main character, so we see things through the eyes of the character trying to prevent the goal from being achieved.
In another, the antagonist might be the influence character so he battles against the protagonist in one storyline and tries to change the beliefs of the main character in the other.
Which form of the Dramatic Triangle you choose is up to you as the author and the kind of experience you wish to design for your readers or audience. But any of the variations is less prone to melodrama than having both story lines between just two characters and is less complicated and easer to fashion than keeping both storylines separate between two pairs of different characters.