Writing a screenplay is hard because there are so many different elements to juggle and intertwine. To avoid overwhelming yourself, just look at three basic elements: your villain, your hero, and your supporting characters.
Your villain starts your story off, even if you never see it occurring. In “Die Hard,” we didn’t need to see the terrorists getting together and plotting their takeover plan. All we need to know is that the terrorists have put their plan into action and Bruce Willis wanders into it.
This is how your villain’s story tends to play out in the four main Acts of your screenplay:
Act I — Villain initiates plan and somehow disrupts the hero’s life.
Act IIa — Villain achieving success with plan but suffering minor losses to the hero.
Act IIb — Villain slams the hero in his place and achieves his goal initiated in Act I.
Act III — Villain needs to complete his plan to create something with Horrible Consequences to the hero and the people the hero cares for.
This is how your hero’s life tends to play out in the four major Acts:
Act I — Hero stuck in dead-end life through his own character flaw, but something that the villain does offers a way out.
Act IIa — Hero enters a new world and achieves minor success while learning new skills.
Act IIb — Hero suffers setbacks and hits a low point.
Act III — Hero overcomes character flaw and confronts the villain.
The hero and villain provide the major conflict, but the hero can never get anywhere without supporting characters. In general, there are major supporting characters and minor supporting characters. Most movies introduce all supporting characters in Act I and IIa. Once you reach the midpoint of your story, you need to use the supporting characters you’ve already introduced and not introduce new ones.
(Find an early draft of the “Star Wars” script and you’ll find that Luke actually meets his father on the rebel base in Act III. Instead of being Darth Vader, his father is just a rebel leader. Notice how introducing a new supporting character this late in the film kind of ruins the story.)
This is how your supporting characters play out the four main Acts:
Act I — A major supporting character butts into your hero’s life.
Act IIa — A minor supporting character appears. Both major and minor supporting characters teach the hero something new.
Act IIb — The supporting characters can only watch helplessly as the hero gets nearly destroyed.
Act III — Using the lessons and skills taught by the supporting characters, the hero can finally defeat the villain.
A major supporting character in “WALL-E” was Eve. A minor supporting character in “WALL-E” was the human couple who finds love because of WALL-E’s influence, and the captain of the starship who helps wrestle control of the starship away from Auto, the evil computer.
Notice that Act IIb rarely introduces new supporting characters because by then, there’s not enough time left to learn anything from them. Basically the first half of your story introduces supporting characters and the remaining half of your movie shows how your supporting characters influenced your hero.
In “WALL-E,” the supporting characters (the captain and the human couple) help WALL-E defeat the evil computer’s plans to maroon the human race in space forever. WALL-E cold never have done it alone, but the supporting characters could never have done it without WALL-E’s help either.
The purpose of your supporting characters is to teach something new and help your hero learn a new way of life, which often means overcoming a character flaw that’s responsible for holding him back in Act I in a dead end life.
Supporting characters are crucial. Without them, you have a flat story about a hero taking on a villain. With supporting characters, you have a hero learning how to defeat the villain, and that’s far more interesting than just a physical battle by itself.