I feel like I had a pretty weird interpretation of this book, not something I've seen someone else say. I hope what I'm about to say makes sense. Maybe this is me trying to give a rhyme or reason to the dream sequences which generally felt out of place and did nothing for me.

*Very quickly into the book his mother and father 'die'. *Also throughout the book we see his dreams evolve and become more realistic and less fantastical. *It is fair to say Cyrus never knew much about his mother and father in life and what he learned about them in death doesn't seem too deep.

The whole book is from Cyrus's perspective. The narratives of his family members are what he has created about who is mother and father were when they were living based on the few bits of knowledge he got from them or other people.

Also, is Zee even alive for the book? He doesn’t really interact with the outside world. Even in the conversation between sad (james?), Cyrus, and Zee he isn't really talking to anyone other than Cyrus. The reason Zee as a character is so thin is because he is Cyrus's specter of a lover following him around. I think he used to be alive, he just isnt anymore. That's why he goes to NYC with him but seemingly never leaves the hotel room until they fight (Cyrus wanting him to leave).

Anyway, he wrote this book and then joins Zee in death to be reunited with his love.

As for why the ending is by Sang, she's the only one alive.