Many rules and guidelines work fine until you sit down to write. As soon as you get inspired, creative frenzy takes over and the muse bolts forward like a mad bull. But there is one rule of thumb that sticks out like a sore thumb: the Rule of Threes.
Interactions and the Rule of Threes
Objective Characters represent dramatic functions which need to interact to reflect all sides of solving the story problem. The first interaction sets the relationship between the two characters. The second interaction brings them into conflict. The third interaction demonstrates which one fare better, establishing one as more appropriate than the other.
This is true between Protagonist and Antagonist, Protagonist and Skeptic, Skeptic and Sidekick — in short, between all essential characters in a story. A good guide while writing is to arrange at least three interactions between each pairing of characters. In this manner, the most concise, yet complete portrayal can be made of essential storyform dynamics.
Each of the characters must be introduced before the three interactions occur, and they must be dismissed after the three interactions are complete. These two functions set-up the story and then disband it, much like one might put up a grandstand for a parade and then tear it down after the event is over. This often makes it feel like there are five acts in a story when three are truly dynamic acts and two have been “borrowed” from the structure.
The introduction of characters is so well known that it is often forgotten by the author. A character’s intrinsic nature must be illustrated before he interacts with any of the Objective Characters. This is so basic that half the time it doesn’t happen and the story suffers right from the start. (Keep in mind that an author can use storytelling to “fool” his audience into believing a character has a given nature, only to find out it made assumptions based on too little information in the wrong context.)
Introductions can be on-camera or off. They can be in conversation about a character, reading a letter that character wrote, seeing the way they decorate their apartment — anything that describes their natures.
The Rule of Threes should be applied until all of the primary characters are played against each other to see what sparks are flying. Once we get the picture, it is time to dismiss the company. Dismissals can be as simple as a death or as complex as an open-ended indication of the future for a particular character. When all else fails, just before the ending crawl a series of cards can be shown: “Janey Schmird went on to become a New Age messiah while holding a day job as a screenplay writer.”
The point is, the audience needs to say good-bye to their new friends or foes.
From the Dramatica Theory Book