so. in storytelling, there are two types of characters. static characters and dynamic characters. both are important.
static characters do not go through a character arc. they have no growth, they're basically the same from the start of the story 'til the end. and you might be asking yourself how that's good writing but I will get there, my friend. I will get there.
a dynamic character goes through a character arc. they grow and change throughout the story. OR they can go the opposite direction! there is positive and negative growth. the point is that they are not the same person they were at the beginning.
think of your favorite enemies to lovers fic. this is a great example of positive dynamic characterization. A and B hate each other at the beginning, but learn throughout the course of the story how to get along. this requires change and ends with them falling in love.
however, it must be acknowledged that these characters are GOING to change. that's why they're dynamic. we as readers must also emotionally go through the process of allowing those characters to change. I think that's something that gets forgotten.
when we begin a story like that, we might see B through A's eyes, and A might not have the best impression of them. but A's lens is very biased. how we perceive B is filtered through A's narration, and thus we may not get an accurate feel for how B's character actually is.
redemption arcs are also an example of positive dynamic character growth. but I think it's also important to acknowledge that not every single character can or should be redeemed. sometimes a story is better when villains are left villains.
which leads into: static characters. static characters can be like background characters, but they're really useful for helping a dynamic character along their arc. they might be someone that A was close with at the start, but over the course of the story, realized wasn't great.
static characters make great villains! such as: Haneul in Black Rabbit. he's not learning anything, he just exists to be an obstacle and force action from the protagonists. Zodiac is another one. he's just more. uh. energetic?
another really good example of this is Jungkook's character in House of Cards. he doesn't go through much personal change. he has the same MO at the end as he does at the beginning, and it takes external forces to put his actions to a stop.
and I think this is FANTASTIC, because not every morally dark character needs to see the light. sometimes that character seeing the light isn't the point of the story. sometimes that character just exists to be... uhm, like a stepladder for someone else's hope. hhksjh.
and then sometimes there's no hope at all! sometimes the ride is just a 1-way ticket to despair town, and that's where we get negative dynamic character growth. they grow, but they like. grow towards evil.
Jimin in Project: 001 is a great example of this type of growth, because we absolutely, unequivocally see him change as a person, but we're also biting our nails because Oh God things are not going well in waffleville.
as a writer, these things are helpful, but as a reader, they're helpful too! when you think about how a character is changing and why, or maybe why they AREN'T changing, it can really alter your perception of a story and help you absorb it better.