I sometimes abuse ampersands

Ah, I see that you have so far escaped my Wolf Hall babbling! Allow me to rectify that immediately.

The striking thing about Wolf Hall, at least to me, is that it's a work that relies for its full impact on the reader's familiarity with a certain specific canon: in this case, a segment of Tudor history. The fact that it is a chunk of history de-geeks it to some extent -- after all, it's perfectly respectable and not too geeky to have some background knowledge about the reign of Henry VIII, and the religious reformations and political upheavals that accompanied and were the background for his changes of wives. It's an episode in English history that has enough draw that many straight historical novels have been written about it, and many readers have at least some rough familiarity with the big names of the era -- Thomas More, Henry himself, Ann Boleyn, all the usual suspects.

Which obscures the fact that if you don't already know this stuff (and know it reasonably well), a lot of what Wolf Hall is doing will be incomprehensible. In fact, I'm not sure it would even make sense if you started it without knowing the basics of canon. Mantel uses a classic fandom trick -- she takes the usual villain as her viewpoint character -- and she uses our knowledge of the canon to give us context for what he does and observes. Part of the pleasure of the book (though by no means the only one) is that particular piecing together of a new narrative from what's not explicitly included in Wolf Hall, but that a reader knows is there, filling in with her own knowledge of the canon. Mantel doesn't do any of the traditional historical-novel work of explaining background or history or social structure to the reader: it's not the kind of popular historical where a reader can go in knowing little or nothing about a place and time, and emerge feeling as though she's learned some history. (Which is something that can be done well or badly, obviously. It's just, that's what your normal historical novel does, almost by definition.)

I think it's for the most part evaded recognition as fanfic, or discussion of it as fanfic within the community, because it doesn't use any of fandom's big emotional tropes. It's not a Mills&Boone romance. It's not full of hurt/comfort, or yearning, or UST. But as a matter of literary form, well, there are reasons it reminded me, more than anything else, of b_hallward's YnM work.

And on the mainstream side, you see it in the way the critics are grappling with it. It's a bit more palatable with Wolf Hall than with The Song of Achilles, though, because with Wolf Hall they at least seen to be aware that there's something alien about it. They know it's an amazing book, and say so, but they don't quite know what to make of it, or what it's doing, or how it works, and in at least one case (the New Yorker review, which I'll try to find the link for), they even seem to be aware of the fact that they don't quite get it.

ETA: On re-reading this, I see that I've failed to make any of the points I intended to make, or if I have, it's glancingly and by accident. I hope the core of the argument -- that it's a work that consciously relies on and requires the reader's knowledge of canon for its effects -- comes through, but for the rest I fear I'm going to have to apologize for going all around my points without ever quite hitting them, and try again when my brain is being more cooperative. I hate it when this happens.