In any work of fiction, change usually only occurs because of conflict. Obviously the kind of changes we are talking about here happen below the surface, even though they might be caused by physical things. Changes in commitment, insight, understanding, and values are the changes that matter, and they are, as I said, almost always the result of conflict. Since The Hunger Games by Suzanne Collins is full of conflict, we should not be surprised that there are characters who undergo changes in this novel.
Haymitch Abernathy is one character in the novel who undergoes a significant change. When we first meet him, he is a middle-aged drunkard with a foul mouth and an equally foul attitude. In the beginning, he is quite an embarrassing figure, and it is clear that he has decided that his job as trainer for the tributes of District 12 is pointless. In fairness, it has been a discouraging task, to say the least; however, he has gone far beyond simply not caring about his job.
When Abernathy realizes that Peeta and Katniss might actually have a chance to succeed at the Games, everything changes for him. He manages to find sponsors for the two young people, providing them the essential support they need to win in the arena. He used his training, knowledge, and connections to help them win. He had all of those things before, of course, but he was prompted to use them (to change) because of the potential he saw in these two young people.
Katniss's mother, Mrs. Everdeen, was once a talented and gifted woman. She provided and cared for her family and was gifted in the art of healing. Once her husband died, however, she suffers a kind of breakdown and is no longer any of those things. Throughout the novel, however, Mrs. Everdeen's behavior changes, and she starts to recover from her emotional loss and grows stronger in every way.
Peeta Mallark is in love with Katniss at the beginning of the story, and he is still in love with her at the end of it, which means there is no change in that regard. What does change in his behavior is his ability to demonstrate his love to her, as well as all the good qualities he possesses. He gave her loaves of bread as a young girl because her family was starving, but now he is able to literally save her life. He does it over and over again, and he is content that she is virtually unable to thank him.
Katniss Everdeen is a strong, independent woman, skilled in many areas of survival that her father taught her. She is fiercely loyal and determined to do what she must to provide for them without any help. She and Gale are hunting companions, of course, but she carries her weight in the relationship. Katniss changes her behavior in several ways throughout the novel.
She has to learn to accept help, something that has never come easy for her since her father's death when she took on the role of caregiver and provider for her mother and sister. In the arena, she lets down her guard and and forms a friendship with another tribute, Rue. Katniss accepts help and love from both Rue and Peeta throughout the course of the Games. She realizes that
[k]ind people have a way of working their way inside me and rooting there.
Even the unbendable, intractable Capitol undergoes a change when the District 12 tributes are about to kill themselves. The couple has been a wildly popular attraction for the people of Panem, and when they are about to commit suicide the Capitol changes its inviolable rules and declares them both winners.