Throughout Suzanne Collins' novel The Hunger Games, how does the protagonist, Katniss Everdeen, change?

In Suzanne Collins' novel The Hunger Games, the protagonist, Katniss Everdeen, undergoes a number of changes over the course of the story.  At the beginning of the novel, Katniss is fearful and unsure of herself. While she illustrates bravery when she volunteers as tribute in place of her younger sister, Prim, she doesn't think she's going to survive and has little confidence in her abilities. She feels almost like she's a pawn in the...

In Suzanne Collins' novel The Hunger Games, the protagonist, Katniss Everdeen, undergoes a number of changes over the course of the story. 
 
At the beginning of the novel, Katniss is fearful and unsure of herself. While she illustrates bravery when she volunteers as tribute in place of her younger sister, Prim, she doesn't think she's going to survive and has little confidence in her abilities. She feels almost like she's a pawn in the Capitol's games and she's basically already accepted that she's most likely going to die. 
 
Before she takes the train to the Capitol, she pleads with her mother to take care of Prim. Katniss reminds her that she'll be the only one Prim has once she dies. On page 37, Katniss even says, "I can't win. Prim must know that in her heart. The competition will be far beyond my abilities" (Collins, 37).
 
However, once she's actually participating in the Games, Katniss is able to hold her own for a long time. She escapes the Careers by cutting down a tracker jacker nest but she's stung in the process and ends up blacking out. When she wakes up, she finds that Rue, a young tribute who reminds her of Prim, has tended to her wounds. Katniss takes a liking to her and the two form an alliance.
 
Things go well until Katniss and Rue decide to separate in order carry out a plan to blow up some of the Careers' food and supplies. After blowing up the food, Katniss is on her way back to their meeting spot when she hears Rue screaming her name. She finds Rue trapped in a net and before she can free her, a boy from District 1 plunges a spear into her. 
 
Katniss kills the boy and stays with Rue as she dies. Rue tells her that she has to win and Katniss responds, "'I'm going to. Going to win for both of us now,' I promise" (Collins, 230). At that moment, Katniss regains her will to fight, for both Rue and herself. She sings to Rue until she finally passes away and then covers her body in beautiful flowers, signifying a proper burial. Then, she salutes Rue with a "goodbye" gesture that's unique to District 12. 
 
By that point in the novel, Katniss has changed significantly. While she's still afraid, she's now angry. She no longer feels like she can afford to lose the Games and will do anything to come out on top for Rue. Though she's still technically a player in the Capitol's games, she rebels against them and everything they stand for by honoring another fallen tribute. 
 
She even says, "I want to do something, right here, right now, to shame them, to make them accountable, to show the Capitol that whatever they do or force us to do there is a part of every tribute they can't own. That Rue was more than a piece in their Games. And so am I" (Collins, 233-234). 
 
That said, Katniss is no longer the cynical, passive girl she was when the novel first started. Now, she's angry, determined, resilient, and most importantly, defiant.