When your story has a strong theme, it has a strong focal point that everything revolves around. Your story is nothing more than a single idea multiple in different ways by your various characters. Whatever your theme, your hero represents the good side of that theme while the villain represents the evil side of that same theme.
For example, in “Terminator 2,” the mentor (John Connor) represents the theme, which is that killing is wrong. The villain (the evil Terminator) embodies the opposite of that theme by trying to solve problems by killing John Connor and anyone who gets in his way.
While the mentor of every story always embraces the theme and the villain always represents the opposite of that theme, the ally, hero, and henchman represent both the good and evil side of the theme. In “Terminator 2,” Sarah Connor represents an ally who thinks like the hero (the good Terminator) and believes that killing is okay, but she changes later when she can’t kill the inventor of SkyNet.
Like the ally, the henchmen often embrace this duality of good and evil. In “Terminator 2,” the police represent good, but they’re working against the hero so they also represent evil. This conflict between good and evil within the ally and the henchmen help highlight the theme for the audience and the hero so both can see the positive and negative aspects of the theme.
The hero, like the ally, starts off in a dead end world that represents the opposite of the theme, but changes to embrace the theme and win. The villain and henchman also represent the opposite of the theme, but they refuse to change so they lose. Basically you can look at the theme as a tug-of-war. The mentor is trying to convince the hero to change and embrace the theme while the villain shows the hero what he or she can become by doing the opposite of the theme.
Mentor (good) —– Ally —– Hero —– Henchman —– Villain (evil)
The ally and henchman shows the hero the ambiguity of the theme beyond a simple black and white, good or evil point of view that melodramas do. Real dramas present the theme in shades of gray, which is the purpose of the ally and henchman. By seeing alternate sides of the theme, the story’s theme becomes richer and deeper. If you simply show the good and evil nature of the theme, the theme comes across as propaganda or melodrama that’s emotionally unsatisfying.
Your hero is caught in the tug of war between the good and evil aspects of the theme. If the hero succumbs to the evil side of the theme, he or she will become like the villain. If the hero changes and embraces the theme by following the mentor’s lesson, the hero will embrace the good side of the theme.
Themes are most powerful when the story lets the audience examine all aspects of that theme, so make sure your secondary characters (ally and henchman) highlight that ambiguity to make a more interesting story.