on Writing Forward:

Characterization may be the single most important element of storytelling. The characters move the plot forward through their actions and dialogue. Readers connect emotionally and intellectually with a story by empathizing with, relating to, or even feeling a sense of opposition to the characters. It is often through sympathetic characters that readers come to care about what happens in a story.

Storytellers must understand what makes their characters tick. What motivates them? What do they want or need? What challenges are they facing? What choices are they forced to make? What are their failures and successes? What makes them interesting? Why should readers care about them?

Only through the act of studying and analyzing characters can we truly understand how they function within stories and how to best use them to tell our stories.