I suppose you are talking about the British paperback version, which has a blond girl wrapped in a blue towel, on a beach. I don’t know who she is except to say that the photo came from a stock photo house, like Getty. I know this photo has been used on other books, too. I think she represents Liz, but you probably know that already.
I imagine this girl was a child model. She’s probably a grown-up now. Maybe she’s in college or even older. Maybe she doesn’t model anymore. Maybe modeling was her mom’s idea to begin with and maybe she only did it to make her mother happy. Maybe she was cold that day. Maybe she wouldn’t like being on a book where the girl dies, but that’s the life of a model: You end up where you end up. Maybe, since the photo is from behind, when she sees the book in stores, she doesn’t even know that it’s her.
At this moment, there sit 84 questions in my tumblr askbox. For the next month, I’m going to try to answer them.