A Mirror in Fidem

When you envisioned a “Great Library,” you imagined something different.
A grand labyrinth of shelves, stacked to the brim with a broad variety of books, topics ranging across all academics, ancient and new, widespread and obscure.
Perhaps the shelves would be tall, constructed of a dark, rigid stone, built to withstand the tests of time.

This is not what the Great Library of Fidem was.
It certainly was not a labyrinth; more akin to a hallway, it stood at an odd two metres tall, and stretched to no more than three in width. It was near claustrophobic in its dimensions.
It did, however seem to make up for this in its sheer scale; if this was a hallway, it could connect two countries. It was unfathomably long, to the point where it had its own horizon. This, you realised, meant it curved around whatever celestial body it manifested upon.
Another thing you soon realised was the near complete absence of books. For a “Great Library,” it didn’t have much to read. You could spot a thin, leatherbound book every few metres, but the shelves were mostly empty.

You picked up a book. The front cover read, ‘A Preface to the Mirror.’ No author. You flipped to the end of the book, only to find it had no pages; all its contents were on the inside cover.
It informed of a grand mirror at the end of the Library. The mirror itself was only described in sparse detail before the writer began to warn of what you saw in it. It only mentioned one of all possible outcomes. The outcome in question was on that seemed paradoxical in nature; the absence of yourself in the reflection.
You noted that by this point the text, handwritten, was quickly devolving, getting messier by the word.
The writer stated that as soon as you saw in the mirror a reflection lacking yourself, madness would envelop you entirely.
The rest of the page was filled with frantic warnings about avoiding the mirror at any cost.
The end of the page was punctuated with a streak of once fresh blood.

It has been 283 years since then. You’ve been counting the days by the light cycles emitted from the backs of the shelves. Time seems to refute its own existence here.
You stopped seeing books 91 years ago. The ones you did see were filled with the deranged ramblings of those who did not see themselves.
The shelves are now completely empty.

The mirror.
It’s right there.
You’ve been walking a while, haven’t you?
Exhaustion is a lie, the Library seems to say.

You’re there.
In the mirror, you’re there.
You breathe a sigh of relief, and relax.

No.
No, why are you calm? Something is wrong.

You take a closer look at the reflection.
The face isn’t yours.