This is referred to as character development or a character arc.

The story line is linear with traditional character arcs.

A character arc generally only affects the main character in a story, though other characters can go through similar changes.

The character arc may extend over to the next story, a sequel, or another episode.

This allowed for shorter character arcs within the larger story.

All you are is someone who fights us", marking the start of Harry's character arc.

The character arcs for most of these people are far too long to cram into six episodes.

A character arc throughout the film is Boy's acceptance of adult responsibilities.

The cancellation of the series left this character arc unresolved.

That character arc has to be structured and obviously it's got to weave in with the music structure.