Sophie is an outcast because she has six toes. In her society, anyone who is different is taken from the family and expelled to the Fringes to live among heathens. Her family protects her by keeping her hidden for most of her early childhood.
Being an outcast has kept Sophie very isolated, and therefore timid. She is not used to interacting with people, and even though she is a gentle and warm soul she has no friends because she is not supposed to exist.
When David first sees Sophie, he is shocked because he knows all the kids for miles around.
She stood still for a few seconds as though uncertain about leaving the security of the bushes, then curiosity got the better of her caution, and she stepped out. (ch 1)
Sophie befriends David, and appreciates his help. She is young and in an impossible situation. She gets her foot caught and David has to help her out. He promises her parents that he won’t tell, and despite the fact that he is Joseph Strorm’s son they believe him.
A blasphemy was, as had been impressed upon me often enough, a frightful thing. Yet there was nothing frightful about Sophie. (ch 1)
Unfortunately, David cannot protect Sophie forever. When a man named Alan sees Sophie’s footprint, the game is up. Sophie is sterilized and expelled. Before she goes, she gives David a lock of hair and a “piece of yellow ribbon” and kisses him (ch 5).
When David sees Sophie again, he barely recognizes her. Her youthful innocence gone, she is now the mistress of David’s Uncle on the Fringes. She cannot give him children, and worries that he is going to replace her with Rosalind. She is curious about David, but one an adult level now.