This was a wonderfully written novel.I loved it, but I hated it at the same time.The writing, the premise and the change of characters every day was incredibly interesting and wonderful and I loved reading this novel. It had been such a wonderful story.But the hate I had against Rhiannon was great as well. She appeared right in the first chapter and took over A's life completely. He deliberately changed his hosts' lives just to go after his obsession. It was not that I didn't like her as a character, she was decent. I also understood why she was so torn between A him-/herself and the every day changing appearance A was forced to live with. But overall I didn't understand why A was so obsessed and in love with Rhiannon and what it made A do in order to get what he/she wants.I also thought of A as a male, right from the beginning. I don't know if this has to do something with the fact that A falls in love with Rhiannon, a girl. Or if this is just something that I thought about as a reader because he does seem male to me. A was just this person who could identify with everybody he spent a day with and I really liked how kind he was and didn't try to exploit his hosts.The writing was just beautiful. I found so many quotes in this novel that I absolutely adored. I have to re-read the novel some time in the future and mark all of the great quotes.I definitely want to read the novella Six Earlier Days to enjoy more of David Levithan's writing and also read his other works.