If you check out a trailer of a new movie or the blurb of a book, you’ll often see a focus on one part of the story, the main plot. The events the main character witnesses. But this is not all you’ll see when you watch the movie. Often you’ll also see what’s happening with the friends, allies, or enemies of the main characters. They might not even impact the main plotline directly, but it is part of the story told in the movie or book. Why are these subplots added when they’re not necessary to get the main plot across?
Why add subplots
The short answer is they make the main plot stronger. Every plot has themes it addresses, and the subplots strengthen these. The themes of the subplot are often parallel to those of the main plot, even when they’re about wildly different things. It’s about the emotions and conflicts in the two stories. If done well, they’re making the main plot so much stronger.
Using the television show House as an example, it’s clear the subplots support the main plot of the episodes. The subplots are usually in the dynamics between him and his team. After the death of his father, the topic of parental relationships came up. The main plot of that episode talked about a woman, her adoptive, and her biological parents. House hated his father, the patient wanted to know who her biological parents were. She didn’t know they tried to kill her. Both House and the patient were hurt by their parents. While these parallel themes are obvious in House, they’re also present in other narrative media. A movie wouldn’t be as strong without such a subplot.
Supporting the big one
Subplots mostly exist to support the main plot but they are also a chance to give secondary or support characters more depth and growth. By giving other characters a chance to show more of their world, the whole story world will feel more alive. The subplots often deal with different things than the main plot, so you’ll see different locations, parts of the culture or political system. The characters of the subplot have their own struggles in their story, of which they are the main character. They grow as characters throughout the story, even when their subplot ends way before the movie or book does.
There are always exceptions of course. Do you know a movie or book where the subplot isn’t relevant to the main plot or does it take over the story?