I have a question.
Before the Library of Souls, the peculiarity of Jacob, Abe, and Harold was basically seeing hollowgasts (this didn't make much sense anyway, since hollowgasts only appeared in the peculiar world a little over a hundred years ago when the experiment went wrong, making it unlikely for such a specific peculiarity to be based on them). However, besides seeing hollowgasts—which no one else could—Jacob could also see souls in the library that no one else could (and I imagine Abe and Harold could as well, even if they couldn't manipulate them like the Librarian).
That being said, we know that wights are 'peculiars' without souls, meaning they lack a peculiarity and the ability to enter loops. Yet hollowgasts can enter loops AND be seen or controlled by the Librarian, who is the only one capable of seeing and manipulating souls. I wonder if hollowgasts aren't actually a type of fragmented soul (like in the ambrosia), and the more peculiars they devour, the more their soul fragments and dries up until they've consumed enough to become wights.
