The protagonists aren't a bear and bird either.
I do think it could be an old hag like Grunty though. Someone else brought it up, that it could be an old librarian. Something along those lines.
Maybe she didn't like the "ghost" writers books, because she feared they would bring too many younger kids into her library. Because she values silence very highly, she decided to just kill the authors and banish their restless spirits into their own, unfinished stories.
Okay maybe you need some kind of magic to do that.
