Hemlock Grove question

Does anyone know/understand who the narrator of the story is supposed to be?

At first I thought the book was self-aware (similarly to old fashioned children's books, such as Narnia or Peter and Wendy) and the author himself was talking, but as I continued to read I grew less certain.

Then I thought maybe it was Roman? Or Olivia? Except... They're not werewolves... and a lot of the narration seems to be werewolf/doggish creature centered... Also there's a line that says the person telling the story is "Sorry," and neither Roman or Olivia strikes me as apologetic natured.

My next thought (with great excitement) was CHRISTINA! This theory seems flawless, since she's such a little spy and would-have-been-novelist, but how did she know about things that happened before she was born? Or Norman and Olivia having an affair? I can believe her knowing a lot about Peter because she watches him often, but I doubt she would have been spying on Norman... Or maybe she's just perceptive?

Which brings me back to uncertainty.

BUT there's actually a part where right after Roman walks in and the only three people in the room are probably Christina, Letha, and Roman, the narrator goes, "We looked at each other". So it's one of them, ISN'T IT? And it can't be Letha, I don't think, so it must be either Roman or Christina, right?

So does anyone know FOR SURE who the narrator is? If the book spelled this out, I think I may have missed it...