In chapter 15, we meet Sophie again. Sophie has greatly changed since we last saw her. At the end of the chapter Sophie kills a guard who was guarding Rosalind. How does this demonstrate how she changed?
In the beginning of the novel, Sophie is basically a normal, good natured kid. She enjoys spending time with David, and is a bit naive about the cultural implications of being a Deviant. She is a bit more worldly than David, because she knows that she should hide the fact that she has six toes. That's probably because her genetic mutation is visible to her and her parents. She has been living with it for her entire life. At the same time David doesn't know about his abilities just yet, so it makes sense that he is more naive than her. Still, she's not a hardened killer.
By the time the reader finishes chapter 15, though, it is evident that Sophie is a vastly different person than she used to be. Her change is not only focused on external aggression and survival, but also her internal attitude about life and society is very different. I like this quote:
"To be any kind of deviant is to be hurt—always," she said.
It shows that Sophie is not disillusioned about being a Deviant any longer. It hurt her to be ostracized as a child. It was painful to be sterilized, and it continues to hurt because she is incapable of bearing children with/for the man she is in love with. That constant pain and suffering at the hands of an intolerant society has made her a cold and hard person. Rosalind and Petra bear witness to that attitude when Sophie kills the guard with little to no hesitance. The final lines of the chapter summarize nicely exactly how much Sophie has changed.
"Rosalind, and Petra too, watched silently in horrid fascination as Sophie scooped a bowlful of water from the bucket to wash the blood off her arms and clean the knife."
She's cool, calm, and collected after having killed someone. That's a far cry from the girl readers first met.
When David and his friends flee to the Fringes, they are jumped on from the overhanging branches. The two girls with him are taken to become breeders since the Deviants cannot reproduce (they have been sterilized). After having been jumped on, David is also dragged outside the Fringe village and beaten severely. When he regains consciousness, he is being dragged by Sophie Wender, who has not forgotten her friend.
Sophie is on her own now and tells David that she will aid him in retrieving the two girls because she does not want Gordon, the extremely tall man who resembles David's father, to copulate with them. From her words and emotions, David gathers that Sophie loves Gordon:
"If she were to give him children, he wouldn't want me any more," she said at last.
After she and David enter the camp, Sophie goes into the tent where an albino stands guard over the girls. However, after a short time, the girls emerge, then Sophie exits, her arms covered with blood. Sophie has obviously become very hardened, and David regrets that he and Rosalind are responsible for Sophie's jealousy and her loss of the innocence that she demonstrated as a young girl who only feared that someone would notice her extra toes. Added to this, David worries for Sophie's safety, but he and the two girls must move on as the men from town pursue them.
In Chapter 15, Sophie resurfaces in David's life. When he regains consciousness from his beating for having attacked one of the men in the Fringes for lewdly looking at Rosalind, he finds himself being dragged by Sophie Wender.
(1) She has matured, of course, and she is in love with Spider-Man, David's uncle, whose real name is Gordon.
(2) David learns that she is infertile, as the deviants have been rendered this way so that they would not multiply. Also, because she envies the girls who can have babies and wants to take them away from Gordon, she tells David that she will help him rescue the two girls that Gordon has taken as "breeders" so that he and others can have children. When they get back to the camp, Sophie goes in the tent and frees the girls, and when she emerges she has blood on her arms.
(3) She is capable, not only of envy, but of murdering the albino who guards Rosalind. David regrets that he and Rosalind are responsible for Sophie's loss of innocence and jealousy, and he worries for her safety, but they must move on as the men from town approach.