Who is Bree from The Memory Keeper's Daughter and what is their importance?

Bree Ascher, Norah Henry's sister, is a rebelliously spirited young woman. She is involved in the protests against the war and against the shootings at Kent State in Ohio, and surrounds herself with politically active friends. She becomes closer to her sister when Paul is born, and she provides some sense of adventure and freedom for Norah that Norah cannot seem to find in herself. Eventually, Bree becomes Norah's business partner, an executive in expensive suits doing business with big clients.