So, what is the Library?
The Library is a place that exists outside of normal space, containing almost every book ever written, and many that never were. There are doors that lead to it all around the world, and in other worlds as well. If you climbed to the top of the shelves, you'd see more shelves as far as you could see. There are walls, there are limits to it, but it's far larger than any man-made building.
The Library exists, so far as anyone knows, to collect and make available books and information. All are welcome to check out books or other materials. Much of the Library's workings are mysterious to its patrons. Some parts, known as the Archives, are accessible only to a select few, while others may only be accessed by the Librarians.
There are a few simple rules to the Library. Return your books on time. Don't damage books. Don't steal books. Don't damage Library property. Don't harm those within the Library. The ranks of the Librarians are filled with those who could not or would not follow them.
The Librarians are the care-takers of the Library, who oversee its day-to-day maintenance. A patron is most likely to encounter one of three types on a given day.
The Archivists serve at the desks in the Main Hall of the Library. They have no eyes, but they know instinctively where to find any book in the Library. They also distribute the Library cards, check books out to people, and keep track of who has which book. If you look behind the desk, you'll find they have no legs, but instead are connected directly to the chairs that are rooted in the marble floor.
Pages reshelf the books in the Library. They have anywhere from six to ten arms, bowed legs, and squat bodies, making them excellent climbers, able to reach the highest shelves without need for a ladder. They rarely so much as touch the ground.
The Docents guide patrons through the Library, showing them where to find books, as well as stalking the stacks for violations of the rules. They are perfectly silent, and in fact have no mouths. Where their left hand should be, a chain grows, connected to a brass lantern that never grows dim.
The Docents in particular serve as the first line of defense for the Library against hostile entities. Some say that they are able to sense the presence of hostile beings even before they enter through a Way, although this claim is controversial, to say the least.
The Ways are connections between various worlds and realities. The Library is a nexus of ways insofar as almost every world is connected to it by at least one Way.
Each Way is a door of sorts. It can be anything from a literal door to an arch to a mirror. To go through, you have to "knock" at it; that is, do a specific action or fulfil some specific criteria. Maybe whistle in the right way or bring a seven-leaf clover or unspool a VHS copy of Enter the Dragon. That sort of thing. You "knock" at the Way, step through, and find yourself in a new world.
Not all Ways lead to the Library. Some lead to other worlds, some lead back to different places in the same world. The greatest minds, including those in the Serpent's Hand, have been unable to figure out how they work. If there's a logic to how they function, no one has been able to discover it yet.
The Serpent's Hand is a group of individuals who believe that the supernatural should not be suppressed or kept secret. Their individual ideologies can vary a great deal, as can their methods. They're more of a loose political movement than a concrete organization. The membership varies from normal humans who want to show what they've learned to others to those gifted with extranormal abilities, and even to non-human entities that desire the acceptance of human society.
While there is some debate about the age of the group, most agree that it has existed in one form or another since at least the late 19th century. For reasons that were unclear, the Hand was unable to access the Library for some time. It was only in 1967 that the Library was "rediscovered" by the Hand.
Despite the Hand's close association with the Library, there is no official link between the two. The Library serves as a base of operations and general meeting place for the Hand, but the Hand has no ownership over it in any meaningful sense.
There is no centralized command of the Serpent's Hand, with dozens of different factions and splinter groups each acting out their agenda under the name of the Serpent's Hand. This lack of organization is a function of the Hand's sole criteria for membership being "a willingness to consider oneself a member of the Hand." More than anything, the Serpent's Hand is an umbrella for those who wish to understand the worlds a bit better. It makes no demands of its members, nor gives any promises.
That being said, there are certain figures within the Hand who, through deeds, scholarship, or charisma, are more likely to have their voices listened to. One such figure is L.S., a leader of one of the more radical factions of the Hand. Engaging against, rather than just avoiding, groups like the Foundation and the Global Occult Coalition, L.S. has made a name for themselves, despite never being seen.