how is sophie wender important in the chrysalids

Early in the novel, David discovers that she has six toes on each foot, thus making her a mutant in their society. Nonetheless, Sophie and David become friends and share a sort of childhood love between them. She is portrayed as a strong, independent, and curious little girl. As an adult living in the Fringes, she is portrayed as resourceful and clever. Martie and John Wender are her parents.