Emily is a Friend of Alison and the others she is Bisexual in the book and Lesbian in the show she dates Maya St.Germain, Samara, and Paige
In the book she has two Sisters and one Brother. Both her parents are together, in the show her dad is in the army and isn't in the book.
She had a crush on Alison and her and Ali keep it secret so no one would know then she disaperred and started dating a guy named Ben.