No character is really innocent, I think that is what makes the show so good to me. Each character is flawed, none are perfectly righteous.
I whole heartedly agree with the idea of Chris being the symbol of America trying to be the good in the world, while managing to make things a more complicated mess. America really is good at that, but dammit we try so hard.
The engineer represents the darker, greedier side of capitalism, another dark mirror in the face of the states.
Kim isn't completely without fault either. She essentially tricks Chris into a marriage that he didn't know he was in. Sure, he intended to many her, but at the point that all of the girls are singing Dju Vui Vai he isn't aware that he is marrying her. She tells him that it's what all of the girls sing at weddings and they are singing it because they don't know what else to sing, prety much reassuring him that it's not really real. However, from then on, she refers to him as her husband. She is really represents a struggle over the loss of innocence. She starts so pure and tries so hard to maintain her virtue, but she gets a husband through a white lie; she kills a man, but does it to save her child; she turns to dancing and implied prostitution, but does it to get back to her husband; and in the end she takes her own life. Don't think I'm knocking Kim. I'm not. This all makes her a nice round character. She isn't a mere damsel in distress, waiting for her prince to return and rescue her. She takes an active role in her destiny. She makes choices, and each of those choices affect her as well as everyone else in the story.
I think that is why we can empathize with each of the characters. Each character is forced to make some very tough, but realistic choices, and that comes to life beautifully here. Each character represents something we can recognize in ourselves.