Who is Emma Paxton from The Lying Game and what is their importance?

Emma is five years old when her mother leaves her with a friend and doesn't return. She spends the next thirteen years being shuffled from one foster home to another. She is scarred by the situation and feels alone and lonely. As a foster child, Emma has learned to become whatever kind of person is most likely to get along in any given situation. That stands her in good stead when she's cast into the role of her twin sister. As Emma puts her life on hold and her safety on the line, Sutton wonders if she would have done the same - evidence of the differences in the girls' personalities. Emma realizes it was a twist of fate that put her in the foster care system and Sutton as the daughter of this affluent family but she isn't really bitter about that. She does feel cheated that she never had a chance to get to know Sutton or to live that kind of life. As Emma puts her detective skills to work, she learns a great deal about Sutton and finds she doesn't like much of what she knows. In many ways, the girls are complete opposites. Emma is serious and wants to go to college though she knows it will be a difficult endeavor. Emma is on the verge of running away but comes to agree that she must remain and try to find Sutton's killer.