Conflicting story characters are the engine of your tales. Do you want your characters to drive the story forward? Then push them into situations of increasing conflict.
In Rob Roy the conflict between Robert Roy MacGregor and Archibald Cunningham involves murder and rape and defines the plot of the story.
Conflict, which is both internal and external, comes from contradiction—contradiction between warring traits inside the character such as fear versus ambition, and contradiction as a result of a clash between two external and powerful wills pitted against each other. Animosity, jealousy, covetousness, hate, and overbearing ambition fighting against their opposites make for a powerful conflict.
Conflicting story character traits heap trouble and misery upon our characters. To rectify a wrong decision a character makes another, drawing on those traits, then another, and a third to fix the second, and so on.
Conflict provides the causality that drives the story forward, like a stack of falling dominos.
Some characters will eventually concede defeat. Others will remain stubborn until they succeed or die.
As a writer, your interest lies in characters who, because of their physical and psychological traits, are predestined to defy the odds and never give up. They are reckless. They relentlessly try to achieve their goal, no matter what.
Such driven people, however, become desperate only after dire necessity forces them to a decision, and any delay in acting might cost them their lives, loves, wealth, health, or honour. Desperate necessity propels them toward their ultimate goal, which is clearly stated in the story’s premise.
The greater the conflict in the characters’ lives, therefore, the greater their growth. End-to-end growth as a result of the journey from jealousy to trust, or from hatred to love, and how it happens, makes for the most satisfying and successful stories.
Conflicting story characters promote growth by causing contradictory traits to collide and resolve themselves into an outcome, allowing one trait to gain prominence over the other.