on Live Write Thrive:

Character arcs are the backbone of compelling fiction. They give readers a reason to invest in the characters, to care about their journeys, and to see themselves in their struggles and triumphs. We love to fall in love (or hate) with characters, root for them, worry over them, and cheer them on when they overcome hard obstacles and reach the goals they are passionate about.

While all characters in a novel can have arcs, it’s the protagonist whose change should be the most significant. Depending on genre and plot, your hero’s change might be subtle or life-altering. A suspense thriller or cozy mystery may show little character growth by the end, when the bad guy is caught or the mystery solved, whereas a thoughtful women’s fiction novel or relational drama may showcase monumental change.