I love this question. But it is hard to give a simple answer. I am, at some level, always myself. Some little valley in my brain always remembers that I am a writer sitting at my desk typing. But other parts of my brain are so completely co-joined with the narrative character that the character is inseparable from me. I feel the pain of disappointment as my character feels it, the shock of a sudden revelation, the joy of a reunion. I feed on the story for sustenance. And the story feeds on me. It’s very symbiotic and natural.
While I am in the process of creating a book, I am its sole life support, it could not live outside me. At least not for long. But after it’s published, you the reader become its life support. And it cannot live without you. Isn’t that amazing?