I agree with anyone who says that the blue fairy wrote the book. The writing of the book could have been the final preparations she was referring to when talking to Gepetto. Also I think it is more likely that the blue fairy knew all those stories and had access to all the information that is in the book then anyone else. She is the oldest source of power in the lands and would know all the stories.
I wonder the show is even going to address the question of who wrote the book because it has been a question we have had from the beginning. Most questions that we have had for that long have already been answered. We may not even get the answer to this question. I hope this is not true because i really want to know.
[adrotate group="5"]