Develop your characters well and the plot will emerge from them
The most exciting part about screenplay writing is that you can take an idea and paint a picture around that idea. Not just a static picture, but a motion picture that could last up to two hours long. The motion picture for sure will have characters in them. These characters will have a past that you can create for them. You can manipulate their lives in ways to tell the story in the most effective ways. You can define their past to justify their current internal and external motivations. And those motivations and intentions will make them react or respond in specific ways to various situations they are faced with. Their past, their needs, motivations and fears will become the basis for conflicts that they get into. The characters may have flaws and internal conflicts that can make them react in unacceptable ways. The deeper these flaws and conflicts the stronger and sustainable the drama that emerges from them as the plot unfolds.
As you develop these characters, you can start to create the spine of the plot. You will craft specific plot points that will include set-ups with payoffs, inciting incidents, build up of tension, false victories, climax and resolutions at the end, as the plot emerges. The sequencing of these plot-points, does draw the audience in and keep them invested in the characters and story till the end. This sequence forms the basis for the structure. You will add additional plot points derived from the characters you have created to lead the audience through a journey, that will feel rewarding for them to have been a part of, at the end. So the characters have to be very well developed with depth, so that the audience continues to be emotionally captivated from FADE IN until FADE OUT. So how does one create such characters?
The protagonist and the story world. Believe that it really exists. The more realistic the story-world and the protagonist is in your mind’s eye, that in itself can prompt the audience to keep watching how your protagonist will respond. Throw in the barriers and external conflicts, which will become fodder for the characters emotions to emerge. The emotions with which the character will respond, are what the audience will identify with and will make them emotionally connect with the story. They get invested in the characters and become part of the journey you take them through.
Develop a back-story for the characters. Not all of it, but only significant portions of it. Again being realistic is critical. Think about the prime motivating factors or the incidents from the past that might have shaped your character as they are in the present. Every aspect about he characters is influenced by the past, their faith, opinions, convictions, and ideologies. It shapes how the character decides what is right and what is wrong. It informs who their family and circle of friends are. It prompts what kind of fears and phobias will drive them away. Remember to feed the audience little by little of this back-story, as the story unfolds.
Develop goals for the character: Armed with all that you already know about the character so far, give them explicit short-term and long-term goals. They must go through their short-term goals towards arriving at their long-term goal. The stronger the character’s goals when faced with conflicts and barriers, the more captivating will the story be. And through the story, your characters may be motivated to set new goals when faced with conflicts. These short-term goals will have to build-up towards achieving the long-term goal of the characters in the story.
Define internal and external conflicts: Based on the characters back-story and internal motivation to self-protect, they have internal conflicts that prevent them from getting what they want. This also builds tension as the story unfolds. And the audience gets hooked into the plot. Similarly, your characters have external motivation to self-preserve with social standing, children, shelter, money, admiration, sex, love, etc. that will have its own external conflicts to deal with. As the character reacts to a situation it reveals a little by little about his/her internal conflict. The external conflicts are relatively more explicit in the story.
Craft the plot: Once you have created the characters with motivations and goals, with internal conflicts and flaws, you create scenes for them to reach to. It is the characters' reactions in the well crafted scenes that will make the most of both the internal and external conflicts. The more you make the external conflicts cater to the internal conflicts and when the characters reactions to them are filled with emotions, the tension grows. It is the internal conflicts that make the plot strong and keeps the characters at odds until the end of the story. On the contrary, the external conflicts can be used to draw the characters in your story together. But make sure that the scenes are well weaved like on a tapestry, through the spine of the story, in a coherent way so that they leave no unanswered questions at the end. It is critical to keep the main story problem very difficult to solve. This way, what is at stake keeps getting bigger as the character keeps reacting to various situations. Something life-changing has to be at risk for the plot to really work well. And that means something in the external life circumstances of the protagonist and/or other people the audience cares about (not just something within a character) that needs to change.
Incorporate emotional triggers: When you watch a good movie or read a good fictional book, always take note of what are its emotional triggers. Most of those triggers are universal. Strong feelings and emotions make us vulnerable. So often many of us are guarded about them. However, you can use your understanding of these triggers, into the characters and the plot to trigger emotional resonance with the audience. As screenplay writers, you have to become your characters and imagine what they would feel like, or how they would respond from our understanding of these emotional triggers.
Make the audience care about your story: Whether your story is character-driven or plot-driven, you have to make your audience care, be concerned and invested in the outcome of your story. Always remember that we have emotional responses only when we feel strongly about something and when a lot is at stake. Each of us is the sum of our past experiences. How we think, what we say or how we act/react to various situations we encounter, are all the result of who we have become today through our past. The audience cannot have a strong emotional response unless the screenplay writer sets them up for an emotional reaction. How the character perceives the world and about themselves, makes them unique and believable as a character. They don’t have to be extraordinary people, because being an ordinary person in extra-ordinary circumstances can be as intriguing as being extraordinary person in an ordinary situation. That is how you create audience identification that is strong with the characters and/or the story. But making the characters realistic and believable is important to begin with. Make sure your characters have insecurities and flaws that make them vulnerable and so believable as well.
Craft an internal narrative or deep point-of-view for your character: The way your character thinks is what makes them sympathetic or unsympathetic. Everything your protagonist thinks will also become the basis for significant audience identification with the story. As the screenplay writer, you become the characters and show their opinions, likes, dislikes and reactions. The internal narrative will give you the courage to become the character, and use the deep point-of-view to allow the emotional connection with the audience. Craft these details about the characters way before you start with FADE IN.
Therefore, focus as much or more of your time on developing your characters, as you would in script writing. If you work with your characters, immerse yourself in their lives, your characters will emerge… and your plot will emerge with it also.