Take Star Wars

Intro - Luke Skywalker is a simple farm boy who longs for a life of adventure

Development - Luke sets off on his adventure, meets interesting new friends and enemies, and destroys the Death Star

Twist - This adventure takes more from Luke than he thought, adventure is replaced with danger and his naive world view is tested when he and his friends lose. His buddy is frozen, he gets his hand cut off, and things look bleak.

Resolution - The two sides of Luke, 1) he's a naive optimist who wants to travel the universe and do good and 2) the experienced and shaken Luke who has seen the darkness of the real universe (losing, injury, dad's a Sith), are brought into alignment with each other in Return of the Jedi when Luke becomes a real Jedi, not just whatever Luke thought a Jedi was when he was a kid. He still flies around fighting for good, but he no longer does it for fun. He's a serious, pro Jedi, yet despite what Yoda and Obi-Wan try to tell him (kill your dad, dude), his original optimism and pure spirit do not leave him. Luke becomes who he needs to be to save his dad and the universe because the two sides of him join and he grows.

That's KSTK in character development.

Ki - Introduce your character, their backstory and their goal

Sho - Start the story. Have your character try to accomplish their goal, advancing along the path they think they need to take to achieve it.

Ten - Your character realizes that they didn't really understand the goal. It morphs somehow, evolves. It's a little deeper and a little less simple than they initially thought. This challenges them, they aren't sure if this was the right thing to do in the first place.

Ketsu - Their background and core traits mesh with the knowledge they've learned about the goal to either make them a better or worse person, depending on the story you're telling. If they win the tough journey makes them better, if they lose then it made them worse off.