I read this book years ago, but it still stays in the forefront of my mind. Recently its been stronger than ever thanks to a friend of mine who loves The Cure. Charlotte goes back and forth through time. living her life, and someone elses. She's only Charlotte sometimes, as the title dictates. The story is eerie, but fascinating, Charlotte makes friend with her 'sister" who is not her sister, but the sister of the girl whose life she sometimes lives. She has to keep this fact a secret, and the plot gets deeper and deeper. The end of the book shocked me with the emotion I felt, especially the revelations that comes at the end. It's sad, bittersweet and lovely all at once, this is the kind of book I would keep forever.