Personal transformations are always at the heart of strong character arcs. Our protagonists are faced with trials that force them to acknowledge their own inadequacies and then, usually, change their ways in a manner that allows them to overcome both their faults and, as a result, the bad guy.
This moment of personal revelation and transformation is inherent in almost every story. Without it, your character remains static, the plot falls flat, and readers are left to wonder, Why did any of that matter?
But including a transformation isn’t enough. You have to offer visible proof your protagonist has changed.

Creating Character Arcs (affiliate link)
Ideally, you accomplish this subtly, gradually, and believably over the course of your story. But you’ll need to drive the point home in two important scenes. We’ll call them “before and after” scenes, and we can find an obvious—if a bit heavy-handed–example in the superhero blockbuster Thor.
>>Click here to read a breakdown of Thor‘s structure in the Story Structure Database.
Within the film’s first twenty minutes, viewers are given a prime “before” scene, which shows the protagonist’s faults of arrogance, intolerance, and recklessness, through his misguided attack on a neighboring kingdom. This scene gives viewers unquestionable proof of the protagonist’s flaws.

Thor (2011), Paramount Pictures.
But without an “after” scene to bookend it, this original scene would be useless. So, right on schedule, just before the Climax, we’re given the proof the events of the movie have changed the protagonist. When he chooses self-sacrifice over useless attack, kindness over arrogance, and forgiveness over intolerance by volunteering to surrender himself to his brother’s anger, in order to save others, viewers have no reason not to believe in the character’s radical transformation.

Thor (2011), Paramount Pictures.
Thor isn’t a perfect example of character arc, by any means. Its pacing and sense of proportion are skewed throughout the middle of the film, but in these two scenes it offers us an imitation-worthy example of how to prove a character’s change of heart.
>>For more on what on you can learn from Thor about character arc, click here: How to Transform Your Story With a Moment of Truth.
One of my characters I have that down. At the beginning she’s just sick and week, but by the end, she can stand there, tortured, naked and bleeding, and praise her creator.
My other character, on the other hand…do you happen to have an posts on redeeming evil characters?
When it comes to redeeming villains, I reflect on Anakin Skywalker, Snape, and Loki. Notice how all of these villains are intimately connected to the protagonist. Yours should be, too. I learned a lot about this connection from a workshop where we analyzed the connection between Lucifer (no redeeming qualities) compared to other villains. It was insightful.
Hmm, nothing particular is popping to mind. But I’ll try to remedy that sometime in the future!
How a character changes is the whole point of their arc–is, in fact, the reason we call it an “arc” and not just a “line.” If you can’t demonstrate change of some kind (even if it’s just a simple lesson learned), you’ll leave your reader feeling cheated and frustrated.
Author changes are important, too. Like when someone checks in on an author’s blog, and doesn’t see a change he was expecting, he can be left feeling cheated and frustrated too. (So, like . . . where’s the new do? 😉
Not *all* stories demand arcs. Sometimes the point is the very fact that the character remains static when he *should* have changed. But these are the exception, and they only work with the author does it to deliberate effect.
I prefer to think in terms of having an objective for each character. Whether that is the evolution of the character or just the premise. So long as they meet their objective, then it’s a solid outcome.
Objective and arc are two different, but inherently related, things. A character can achieve an objective without necessarily having changed on a deeply personal level.
Protagonists don’t need to change, but I’ve always felt closest to the ones that do. Static characters/protagonists like Gandalph (he really doesn’t change) or Rose from An Old Fashioned Girl create change in OTHER characters. I have one or two static characters but the rest are dynamic (changing) characters. One goes from being a doubter to a seeker on his quest for redemption and the other goes from being guarded and jaded against friendship to sacrificing for it. Not all change has to be huge and the characters that leave the lasting impressions on my mind flex both ways. They become better and they relapse, and become better again.
Good analysis. I’ve always been most fond of the changing protagonists as well, although static minor characters area often a joy (particularly the humorous ones).
My story begins with an unlikeable character (risky, I know) and the change in him by the final chapter is amazing (IMHO). Thanks for the great reminders!
I know you didn’t like Thor’s arc in Endgame, but I’ve read comments from combat veterans who said Thor’s response to losing to Thanos in Infinity War was realistic to them. A hardened warrior doesn’t handle losing a war easily and his retreat from reality into escapism mirrored their own behaviors caused by PTSD. I found their critique to be insightful.
I’m interested to see how it works for me when I get a chance to view it a second time.