Beautiful Creatures is a novel by Kami Garcia and Margaret Stohl
If you are planning to read the book, it might be better to skip this post, although I don't give too much away.
Marian is the librarian of the Gatlin County library by day. She is a cheerful and friendly woman who is a bit of a noncorformist in a rather conformist little town. But she also has another job. She runs the Domus Lunae Libri, also known as the Caster Library. This is a library that is vast and hidden underneath the normal library. It can only be accessed at night on public holidays, when the normal library is closed. It contains countless books relating to magic. While Marian is a mere mortal, not gifted with any kind of magic, as are the Casters and creatures who check out books from the library, she is knowledgeable, brave, and always willing to help.
I won't say much more, because I don't want to give away the plot of the book to anyone who hasn't read it. But she is definetly the sort of librarian I would like to be. I mean, I probably won't be working at enchanted library (although there's always hope) but I would love to be as resourceful and dedicated as she is!