I know most readers don't like prologues, so I've tried to make it as simple as possible.
I write the following knowing fully well how weird it’ll make me look. — A.B.G.
A.B.G. Is the fictional (undisclosed) author of the novel, which is set in 3rd person. She never shows up again, and this is only meant to show the readers that this is the writer of the following story. Will readers understand this? Or is it too short that it's confusing?
It is not uncommon for fictional works to start with quotes from real or fictional personages. Dune, in particular, makes heavy use of this tool, starting every chapter with excerpts from fictional history books, written by one of the main characters, and providing commentary, and "additional sources", and additional perspective, to the narrative.
However, there is an expectation for things to come together, fit together in a story, for all ends to be tied up nicely. If your A.B.G never shows up again, is never mentioned again, never makes any sort of appearance, it's like a broken link, a path that leads nowhere. Readers would find it disappointing and confusing.
If you "quote" a fictional character you've created, they should make an appearance in your story. Moreover, it should be clear why it's them that you're citing at the start of your tale. If a fictional character makes the claim that they are the writer of the story presented to the reader, it must be made clear why it is they who are the writer, what this perspective adds to the story, why it's not just your (the real writer's) novel instead.
I think what you're looking for is Epigraph.
I quite like when books have those, but singular on its own it is not a prologue in any way. Also, introducing a character, that appears in one sentence only in the entire book? I don't think so. It'll be ignored at best. If there was a comment by said character at the beginning of every chapter on the other hand, you'd have plenty of opportunity to develop that character more, or even break the 4th wall a little.
It's not a prolog, it's a disclaimer, but the warning is unclear.
There are a few problems:
Is the author concerned about how the story is received (it only seems weird at first), or their own image (the story is weird, but I am not)?
Meanwhile, the author is almost anonymous, signing with just initials so readers who know what A.B.G. stands for may be able to confirm parts of the story, but readers outside the author's circle will not be able to connect details to anyone specific. Who is the prolog for, a reader who knows nothing about the situation, or a reader who already has an opinion of the author (and this story will shake that opinion)? If the author is anonymizing their name, why be concerned what the reader thinks of them personally? They are not relying on their reputation, and they are distancing themselves from the events.
As a prolog, it doesn't work to make the situation clearer. It's actually a mixed message: "Trust me, I'm going to lie to you" would be a similar mixed-message. Is the author discrediting themselves? Is this already part of the weirdness we should expect?
Consider a similar one-line disclaimer/epigraph by Evelyn Waugh in Brideshead Revisited:
"I am not I; thou art not he or she; they are not they."
At first it seems like a typical "This is a work of fiction…" disclaimer, but it is worded in such an oddly personal way that it appears to specifically address people who will recognize themselves in the novel, and this brings into question the accuracy of the statement as a disclaimer. If he needs to mention it at all, especially to the people who were "there", it probably resembles the truth. So in a way, it works to confirm aspects of the story, rather than deny it.
+1 Galastel. This prologue has no purpose, readers don't care who wrote a book, and you say this makes no difference in the book itself. If it were a 1st person book, this is not needed; the MC wrote it. If it is a 3rd person limited book about the MC Mary, then trying to explain who wrote it is likely to break the reading reverie; and it is unimportant.
It looks to me like you, the author, are trying to apologize to the reader or give them a heads up that you are about to tell a weird story. Perhaps asking them to not give up on it, because it is weird.
Don't do it. Just tell a weird story, or if you truly think it is not entertaining as it stands or cannot be followed as it stands, then fix your story so it isn't so weird.
