If you want to write a weak, mediocre screenplay with poor character development, just focus on the hero’s story. However, if you want to write a great screenplay with fully developed characters, you need to focus on more than just the hero. You also need to focus on the villain, mentor, and ally as well.
By creating multiple stories, you create a richer overall story because every major character is pursuing a goal that all ties together somehow in the end. This keeps the other characters from appearing one-dimensional with no purpose except to advance the plot.
In “Avatar,” there’s the hero who wants to get his legs back after being paralyzed. There’s the villain who wants to wipe the aliens out so the humans can mine the natural resources. There’s the mentor, the hero’s alien girlfriend, who teaches him how to appreciate nature and wants to protect her home. Finally there’s the ally, the scientist who helps the hero get in and out of his avatar body and wants to learn more about the alien culture.
What makes multiple stories interesting is when they intertwine somehow. Initially, none of these major characters necessarily care about each other but through the plot, they start caring because each major character either helps or hinders their own goal.
For example, the hero just wants to get his legs back so he initially cooperates with the villain in scouting out the alien village and how they operate. The hero’s ally wants to use the hero as just one more tool for learning about alien life on the planet. The hero’s mentor initially wanted to kill the hero but decides to help him after seeing a sign that he should be protected. The villain wants to gather military intelligence on the aliens so he can wipe them out so he sees the hero as just one more way to do that.
Essentially, each major character uses the others to get what they want. In the process of getting what they want, the hero, mentor, and ally threaten the villain’s goal. Because only the hero or villain can achieve their goal, the climactic battle in the end is literally a final fight to the death. if the hero wins, the villain loses. If the villain wins, the hero loses. Every screenplay must eventually resolve this fundamental question of who wins in the end.
Although it’s easy to see that the hero directly opposes the villain, the other characters also oppose the villain but not directly.
In “Avatar,” the villain takes a warlike stance towards the aliens so he dismisses the hero’s ally (the scientist) as a waste of resources, but he thinks he can use the hero as a Marine to scout out the alien forces. The villain’s goal is already conflicting with the scientist’s goal and ends when the villain shoots the scientist and kills her.
The villain is also indirectly opposed to the hero’s mentor, the alien girlfriend. Since the villain wants to wipe out the aliens, he also wants to wipe out the hero’s girlfriend too. By putting the villain in direct conflict with both the hero’s mentor and ally, your story starts off with a strong foundation of conflict.
Think of “Star Wars” where before the story even begins, Obi-wan (Luke’s mentor) is already in conflict with Darth Vader (villain) although we don’t know this at first. Princess Leia and Hans Solo (allies) are also in conflict with Darth Vader. While Princess Leia is directly aiding the rebels against Darth Vader, Hans Solo is indirectly in conflict with Darth Vader when he helps Luke get off his planet. Whether he knows it or not, now Hans is fighting against Darth Vader’s goal of wiping out the rebels.
So in your own story, think of your four major characters (hero, villain, mentor, and ally) and make sure that your hero, mentor, and ally are already or soon to be in conflict with your villain. If there’s no conflict between these three major characters and your villain, chances are good your story is flawed so fix it.
Conflict is necessary to create suspense and multiple stories defined by every major character pursuing a goal keeps the story active and interesting.