Okay, when we said there were no other characters of note besides the obvious protagonist, the librarian, we really weren't kidding. But we do think it's worth mentioning that there's one mysterious figure hidden within the text that – in typical Borgesian fashion – totally changes the way we understand the main character, and even the story as a whole.
So who is this masked man, you ask? Well, take a look at the first footnote in the story (it pops up within paragraph 5). It ends, in brackets, with the phrase: "[Ed. note.]" This is an editorial notation indicating that this comment was written by a later reader – an editor.
Let's pause for a moment to consider what this means. Someone else – not the librarian – has found the narrator's "original manuscript," edited it, and republished it. What does this say about our beloved librarian? How much time has passed since he wrote this essay? Years? Centuries? He must be dead by now, right? Have the human inhabitants of the Library survived after all?
These are some seriously big questions, but we're not finished yet. Let's take a closer look at this footnote.
The Editor squeezes in this particular comment right after the librarian has told us that "There are twenty-five orthographic symbols" (5). This is a basic premise of the universe of the Library. There are 25 symbols, and that's it. No capital letters, no question marks, no hyphens... and no brackets. The Editor's need to explain these limitations tells us something very important – he lives in a world that has brackets! And capital letters! And question marks! And numbers! And all the typographical symbols that we're familiar with!
This revelation raises a very disturbing possibility. Could it be that the Editor exists outside of the Library? Perhaps in another universe? Could it be that he exists in our universe? Does that mean that the librarian's idea of the infinite Library is completely false? There are a lot of possible interpretations here, so don't let us limit you. What do you think the explanation is?
See how the teensiest of interjections by this anonymous character can cause us consider our position as readers in relation to the text? And see how it also causes the entire logic of the text to unravel?