If we go, we go with glory;
Unlike most lead characters in videogames, Chris begins the story a hero. She isn't some orphaned farmboy with a mysterious crystal and no memory of the past. Chris and her knights start out at higher levels and with more money than the other two beginning parties. Chris is already marching in a parade, recognized and even loved by the people of Zexen. This is one of the things that makes her journey so interesting. Instead of going from zero to hero, Chris moves in the opposite direction.
Even though she is the mythic Silver Maiden, it doesn't save her from making mistakes on the battlefield. When a small child attacks her, her reaction is almost robotic. She parries and counters, and the boy is dead on the ground. She doesn't even recognized he's a child, all she sees is the enemy. She doesn't realize until it's two steps to late. For all her reputation she can't bring the dead back to life.
When the council comments on her legendary status, Chris simply says "I have not lived long enough to become a myth." She is forever stating that a hero's title is meaningless to her. While she certainly isn't actively seeking glory, that's not precicly true. The weight of expectation bgs her down. To top it off, she's afraid of voicing her concerns, because she really isn't all that confident. Her own self-image is completely at odds with how others see her. The result is she comes off as an overly-honorable ice queen.
But the truth is that it really gets to her. That's why she leaves her position and follows a rather sketchy older man through enemy territory. It isn't just the promise of her father. Chasing the Flame Champion is chasing the sort of legend Chris has become. Learning that the Flame Champion gave up his immortal life as a hero to spend his limited days with his wife gave him a human quality. But most of all, meeting a young woman wise beyond her years and with such faith in Chris changed her. Because Yun, with her kind face, and her certainty in her sacrifice, is more of a hero than Chris ever was. Meeting Yun cemented Chris's growing suspicion that heroism is more than empty glory. Her reputation was out of her control, turned into a political tool and manipulated to unsavory ends.
When Chris returns, it is with a new confidence and a new faith. Her determination to succeed on the battlefield was "fueled by being hated.". I think that at the end of the game, she fights because she knows she is loved. She knows it is her job to protect Zexen. And she knows that's all she can do. Her reputation might not be her own, but she can choose what to fight for.
If you choose Chris as your Flame Champion, before the final fight, the Masked Bishop will explain his motivations. He doesn't want to be controlled by a cruel destiny. He was created by Harmonia as a pawn or vessel, and feels he doesn't have any control over his actions. His own sacrifice will give humanity a real freedom. Chris knows all to well what it means to be moved by something larger than oneself. She might not understand the finer points of his philosophy. But it doesn't matter.
Chris: You talk about destiny and freedom, but they matter only after your everyday needs have been satisfied. Are you really ready to sacrifice human lives for your destiny and freedom? Do you comprehend the importance of human life?
(Un)masked Bishop: I've learned a lot. I have good reasons for doing this, even if it means being responsible for taking the lives of a million people.
Chris: Then I will be the last person to stand before you. I will become the shield to block you. This is the reason I am a knight!
Her duty is not to bow before a nation or an ideology. It is to protect, cherish, and celebrate human life. This has nothing-- and everything-- to do with heroism. This is what makes Suikoden III an anti-epic. The world doesn't stop moving for the game's characters. They aren't chosen by destiny as the one savior of the world. You even have a choice between three main characters. As Yun said, "You don't need qualifications to make a difference." Chris's quiet determination looks rather small compared to choirs singing in Latin that accompany other game's cast. But hers is the truer heroism.