Beneath the moonlight glints a tiny fragment of silver, a fraction of a line...

(black robes, falling)

...blood spills out in liters, and someone screams a word.

That, of course, appears before the start of Chapter 1. It's gotten a lot of attention and a lot of speculation. Clearly it depicts something that happened in the past, or that will happen in the future, and we'll all get lots and lots of goosebumps when we figure out what it is.

But that passage has a little brother that I haven't seen anyone talk about. Before the start of Chapter 2, we get this:

"Of course it was my fault. There's no one else here who could be responsible for anything."

That doesn't sound that significant. It sounds like Harry Potter, to be sure, but it sounds like it could happen anywhere. The little blurbs before the chapters that follow do appear in those chapters, or at least in chapters nearby (I believe the Chapter 3 blurb appears in Chapter 6, and most of the rest appear in the body of the chapter they preface).

But this one does not. As far as I can tell with both grep and Google, this passage has not yet appeared in the story, 84 chapters later. Clearly it either (a) slipped Eliezer's mind and hasn't been revised in his several retcon binges, or (b) is way more important than it sounds.

To me, if I accept that this line must be important, it maybe sounds like something Harry would say after doing something really dark and evil, while he's in the depths of his Dark Side. Like, something horrible happens and it's not 100% clear that he did it, or someone like Dumbledore is in disbelief that he did it, and instead of denying it he just says "Of course it was me, idiot, who else?" Or maybe it's after he's out of his Dark Side, he realizes what he's done, and instead of trying to save himself he's just completely numb and confesses in a monotone.

EDIT: Or it might be Quirrell, sarcastically referring to everyone else's suspicion that all bad things must be the Defense Professor's fault. If so he's probably either confessing for real because he's beyond caring whether people know, or maybe he's hiding the truth in plain sight with false irony.

But I haven't been around for very long, so it's possible that people have whole edifices of theory about this quote and just don't talk about it because it's old news. Has it been talked about? If so, what's been guessed? If not, what do y'all think?