Screenwriting 101 - Creating Believable Character Motivation

Films and shows, as outrageous as they can be, still operate under believable human motivations. If a character’s reasons for acting don’t translate understandably to the viewer, the story could be disregarded as unbelievable, even if it’s set in a galaxy far, far away.
But what can a screenwriter do to compel the audience that a character’s motivations are strong enough to motivate momentous action? What could make our hero leap off cliffs, face dragons and take down space tyrants?
In Robert McKee’s Story, the established screenwriter describes this subject as “the principle of antagonism”:



