Screenwriting expert Danny Munso explains why well-developed supporting characters are crucial to any screenplay’s success

To write a good screenplay, you should have the following two elements: an original story and a unique character to centre that story around. These two items alone are enough to make a competent script. But if you want a great script, you’re going to need more. You’re going to need supporting characters that are as complex as your main protagonist. You’re going to need to make sure that the relationships between the main and supporting characters are vital to the story you are trying to tell.

Supporting characters can be easy to overlook when you are an unproduced writer. Most screenwriting seminars and books focus on the main character and, yes, this is clearly important. But what makes that character who they are—and what makes us people as well—are the relationships they have with others. Just as you wouldn’t tell a story of your life without the contributions of the important people within it, don’t tell your protagonist’s story absent of supporting players that both move the plot forward and enhance the audience’s view of your main character. Focusing on the individual but neglecting to develop their relationships with others will ring hollow to both a reader and a viewer.

A simple and effective way to do this is to contrast your main character with a supporting one. For a great example of this we can look no further than George Lucas’ Star Wars. The dynamic between Luke Skywalker (Mark Hamill) and Han Solo (Harrison Ford) is a perfect exercise in how contradicting characters can create a strong on-screen bond that the audience can connect with. Whereas Luke is a wide-eyed idealist, Han is a selfish cynic. Though these archetypes existed long before Luke and Han were names on a page, Lucas was wise to create this dichotomy between these two. By clashing heads through the better part of the film, it developed an on-screen tension and added to the drama that was already there. Escaping the Death Star is one thing, but disagreeing on how to achieve that adds an additional layer to the narrative. Furthermore, their differences and disagreements pay off that much more when they unite for the same goal in the film’s climax. While Luke and Han are great individual characters, the main reason the audience loves them so much is because of their relationship with one another.

Some of the best supporting characters earn that recognition because not only do they help forge a relationship between the main character and the audience, they also serve the greater plot line of the film they’re in. One of the most iconic moments in film history happens for this very reason. In The Godfather: Part II, Michael Corleone (Al Pacino) discovers he was betrayed by his younger brother Fredo (John Cazale). This plot device serves two purposes to the film: a practical one and an emotional one. Practically, Fredo’s action drives a main plot thread, in which an assassination attempt is made on Michael’s life. Emotionally, his betrayal allows the audience to witness Michael’s further descent into a cold, ruthless mobster. By the time Michael has Fredo executed at the end of the film, we know his transformation is complete.

For a different take on this type of supporting character, look at the film Cast Away and the relationship between Chuck Noland (Tom Hanks) and the volleyball he turns into a makeshift friend, Wilson. The emotional connection that Wilson provides is obvious; though an inanimate object, the ball becomes the only source of comfort and companionship to Noland for the four years he spends stranded on an island. But Wilson’s practical purpose is a clever trick by the screenwriters: by forging a friend for Noland, the film now has a way for us to understand what he is going through. With no Wilson, we would be looking at Tom Hanks on screen for three hours, not saying a word.

The final use a supporting character can have is a thematic one. This is a difficult element to add to your screenplay, but it can pay huge dividends. A recent example of this is the 2011 film The Help, based on Kathryn Stockett’s novel. The roster of characters in that film is long, but it’s a small part that makes one of the largest impacts. After Minny (Octavia Spencer) is fired from her current job, she takes up with a new household, led by Celia Foote (Jessica Chastain). The pair bond—important because Celia is white and Minny is black and the story, set in 1960s Mississippi, is one of racial integration.

The two seemingly different individuals have much in common. Celia, though married to a rich man, is outcast from the main characters in the story due to the fact that she is from a working-class family and married an ex-boyfriend of Minny’s former employer. If you were to lie out the important plot threads of The Help, Celia might not warrant a large mention. But her and Minny’s relationship is a key thematic beat. Not only do they bridge the differences that supposedly surrounded whites and African Americans at that point in time, they form a mirror image to the main relationship between Aibileen (Viola Davis) and Skeeter (Emma Stone), who are collaborating on the book that will cause shockwaves through their community.

To understand how vital great secondary characters can be to a screenplay, all you have to do is try and imagine the films mentioned above without these crucial parts. So give just due to your story and main protagonist, but keep in mind that surrounding those elements with well-rounded and important supporting players will make your script that much better.