What I mean is that Henry would have known who Gold was: Rumplestiltskin, nothing to do with his family, but he would have known that Gold was Rumple and the Dark One but he tells Emma that he can’t figure out who Gold is.
Mr. Gold: Hey, Henry. How are you?
Henry: Okay?
Mr. Gold: Good. Give my regards to your mother. And, um, good luck, Miss Swan.
(Mr. Gold leaves.)
Henry: Do you know who that is?
Emma: Yeah, course I do.
Henry: Who? Cause I’m still trying to figure it out.
He knows who Ruby and Ella are because they are in the book and he’s read it. He hadn’t figured out that Ashely is Cinderella until her situation is pointed out, but he instantly figures out that she’s Ella. Same with Red/Ruby.
Rumple is in the book, but as a character in other people’s story: like in Ella’s story about the quill which was the first time we learned that Rumple was in the book *at all* for sure. And his ability to see the future is in the book, but that’s in the Snow/Charming story that we saw in the Pilot.
Rumple’s situation of being the Dark One manifests in our world as Gold being the most powerful man in town and if the story of the Dark One was in the book, Henry would have put 2 and 2 together. He’s very smart.
And I think this quote from Manhattan shows that Henry didn’t know about the circumstances surrounding Bae’s departure, which I think singles that the story of the Dark One isn’t in the book.
Henry: You know… I forgave her. Emma – for giving me up. She thought it was the best for me then. That’s why she did it. I’m sure your son will get it, too.
Mr. Gold: Alas, the circumstances surrounding our separation weren’t quite so noble