For the record, I have no idea if this is legitimate and/or refuted by an episode I haven’t seen (desperately, desperately behind), but S T I L L.  This fic would be the story of the Library’s favorites through the millennia (she is a library, after all–her favorites are wordsmiths and silver-tongued diplomats, world-changers and storytellers).

The Library is sentient.  This is not a commonly known fact–sometimes Librarians go their whole career without even realizing it.  She does not particularly mind this.

(Sometimes, in the netherspace where she has a shape that is more woman than building, she meets with others like herself.  A waif of a boy, the thirteenth of his kind, whose eyes crackle with purple lightning, tells wild stories of heroics and villany and…goo?  A slender willow-wand fae dressed in ragged white and trailing glittering dust in her wake complains of her lovesick king and the mortal girl who defeated him.  The boy is young, only centuries old.  The willow-wand is ancient, even older than the Library.  There are others, but these are the eldest and the youngest, the bookends of their kind.)

The vital thing about a sentient being is that sentient beings have favorites–it’s unavoidable.  The Library being rather fickle, not all of her favorites are Librarians.

Galahad is sheltered in her Annex on the merits of his old friends, more so than on his own.  Merlin asked, and she loved him, so she did as requested.  Merlin isn’t quite like her, but he’s not quite human either, and sometimes, very occasionally, she will sense the touch of a hand on one of her many doors as Merlin passes by.

Greek and Rome were riddled with poets and philosophers–the others like her had varying opinions on them.  She was fond of Catullus with his filthy sense of humor, and of Plato with his unusually good grasp of the netherworld, but, oh, Sappho she loved.

Sun Tzu was too warlike to be a Librarian, too much a tactician and not enough of a dreamer, but she would slip him secrets of long-dead armies in his dreams to bolster his writing.

Poe and Shelley and Byron and Keats–she did love the Romantics.  They were her favored for years, brilliant comets that burned out so fast.  The willow-wand shook her head at the Library for it, remarking on the merits of immortal citizenry.

But William–William was her best beloved, her most cherished mortal favorite.  She would be hard-pressed to find someone to stand beside him and his golden words and dirty jokes and impossible wisdom.  Not even the willow-wand could hold that against her, her immortal faerie residents drawn to his starlight words like moths to a flame.

(When Prospero first stepped into her walls, she had a moment of blind hope that maybe, somehow, her dear Shakespeare had returned to her.)