Want versus need

A character's want is the conscious goal they pursue and could state aloud, while their need is the unacknowledged lack the story forces them to confront — and the two are usually in conflict.

The want drives the plot; the need drives the character arc. One is the thing the character is chasing across the pages, the other is the thing they will have to accept in order to stop chasing it — and the story tends to be about the distance between them.

The want has to exist from very early, and it does not have to be grand. Kurt Vonnegut's rule is the plainest statement of it: make your characters want something right away, even if it is only a glass of water — characters paralysed by the meaninglessness of modern life still have to drink water from time to time. A character with no stated want is a passive protagonist in waiting.

The need is the harder half, precisely because it is unconscious: a desire the character does not know they have — security, acceptance, forgiveness — which their stated want is an attempt to satisfy sideways.

It is worth separating innate motivation from plot motivation while drafting. Innate motives (adhere to the truth) rarely change and feed everything else; plot motives shift in response to events. When a character's behaviour stops feeling coherent, it is usually a plot motive that has quietly overwritten an innate one.