Author

The term author is used by several characters in the series to refer to whatever cause or force created Henry's book. The choice of name indicates that the characters believe the book was created by some kind of sentient being, or at least find anthropomorphism makes it easier to converse about the concept. Regina refers to the author using male pronouns, a habit then taken up by Rumple then Ursula.

Henry and Regina refer to their pursuit of the identity of the author as Operation Mongoose. When Rumple informs Regina that he was aware that Henry was snooping through his shop for clues (though he does not appear to know why) Regina reveals their pursuit to him. Emma is also later informed of it.

Later, Rumple approaches Ursula and invites her to join him in searching for the identity of the author. He then mentions they have 2 more stops to make, likely indicating the other 2 members of the Queens of Darkness, Cruella and Maleficent.

Relevant quotes
This shows how in one episode, the circle of author-seekers expands from 2 to 5, and the inherited habit of using male pronouns to refer to the unknown quantity.

Heroes and Villains
Regina-Gold conversation:
 * Regina: The storybook has me written as a villain, and villains always lose, so he thought you might have a clue as to who the author is so I can make him change that.
 * Gold: Alas, I've no clue as to his identity.

Regina-Emma conversation:
 * Regina: maybe this is the author's house...
 * Emma: What's going on?
 * Regina: We were looking for the author. I was hoping he could write me a happier story.

Gold-Ursula conversation (6 weeks later):
 * Gold: There's someone who can change those rules. .. For now let's call him "the author".
 * Ursula: Pretentious, I hate him already.