Who was Nancy, and what did she do for the gang?

Nancy was raised by Fagin.... she is a prostitute. She is in love with Bill Sikes, and she does just about anything that Sikes or Fagin tell her to do..... note, they do not ask. Nancy's big heart, however, goes out to Oliver, and she wants him to have the chance to get out.... to escape the slums and Fagin's control. Oliver has people who care about him, and she cares about him as well. Her betrayal leads to her death.