The Library itself appears to be sentient (or semi-sentient) and sends out invitations to prospective Librarians and Guardians. The 'Library' has existed at least since ancient times, and houses both magical and powerful relics. The Brotherhood take their name from the serpent that brought knowledge to Adam and Eve. The current leader of the Brotherhood is Lancelot du Lac.
In 2014 they attempted to seize control of the 'Library' forcing Judson and Charlene to sever the link between the 'Library' and the New York Public Library. More recently, in 2004 the Brotherhood worked with former Librarian, Edward Wilde, to unsuccessfully steal the Spear of Destiny, to take control of the world. The Brotherhood wished to use the powers of the artifacts to rule the world and this disagreement led to a secret war between the Librarians and the Brotherhood who incited the riot that led to the destruction of the entrance to Library (in Alexandria). The Serpent Brotherhood are a splinter group of the Librarians, who separated off back when the "Library" entrance was in Alexandria in ancient times. Jenkins/ Galahad - He is the caretaker of the Portland, Oregon annex of the 'Library'.Leo - He worked in the Library, and was supposed to put the Shroud of Turin away.Eve Baird - She works for the Library and served as Guardian first to Flynn Carsen and then to three potential Librarians (Jacob Stone, Cassandra Cillian, and Ezekiel Jones).Nicole Noone - She works for the Library and served as Guardian to two Librarians (Edward Wilde and Flynn Carsen).Charlene - She works in the Library and was Guardian (bodyguard) to a previous Librarian.He is a highly intelligent and resourceful adventurer. He faked his own death to steal the Spear of Destiny. Edward Wilde - The previous Librarian before Flynn.When Darrington learns there are currently three other Librarians besides Flynn, he tells Flynn the history of the Westphalian Brothers, and emphatically urges Flynn to fire the other Librarians before it's too late. Due to a time slip/crossover incident, they get to meet and work together in "The Bleeding Crown". Darrington Dare is Flynn's ultimate hero. Darrington Dare - The Librarian of the late 1800s, who claims that Arthur Conan Doyle used him as a model for Sherlock Holmes.Brought the remnants of the Library of Alexandria back to the Library and created the Bermuda Triangle to hide the Eye of Ra. Teddy Chislington - The Librarian in the mid-1800s.The letters were correspondence between the Westphalian Brothers (AKA Balthus and Zharradan), which chronicled the genesis of the war between them. She gave Jenkins/Galahad a stack of letters "on Shrove Tuesday 1782". Mentioned only once in the episode "And a Town Called Feud". "Eccentric in her working habits", employed a filing system of nearly incomprehensible clues in a scavenger hunt style, for which Cassandra nicknames her "Zelpha the Infuriating". Zelpha the Forgetful - The Librarian of the late 1700s who first established the Archive.Judging by his style of dress he can be placed in Europe during the 1600s. Unknown His painting seen next to Eldred's.Possibly instrumental in restoring order after the war between the twin brothers. Eldred the Truly Wonderful - A historical Librarian who was considered great.
(Presumably, this is when the split off occurred that gave rise to the Serpent Brotherhood). Their rivalry led to war, which ultimately plunged the world into the Dark Ages and nearly destroyed the Library. Eventually the brothers became jealous of one another, each believing himself more suited to be the Librarian. Identical twins chosen simultaneously by the Library in the 5th Century. Balthus and Zharradan - aka "the Westphalian Brothers".Enoch the Elder- Mentioned in Librarians Season 3 episode "Trial of the Triangle".He was known as Yahuda which is the Hebrew name for Judson. Judson aka The Scholar - The greatest Librarian of all, legend says that over two thousand years ago he built the Library and is the keeper of its secrets.There have been many librarians of note over the centuries, including Simone Renoir states that all vampires are aware of the Librarians and their battle against evil. They have been fighting a secret war with the Serpent Brotherhood since at least the fall of the Library of Alexandria many centuries ago. The Librarians wish only to increase their knowledge, and use the relics for the betterment of mankind.
The Librarians are a fictional secret society that have existed as an order for centuries, and often undertake global-spanning adventures to recover items to keep them safe from people who would use them for evil purposes.