There are currently a couple of debates going around - about the problem of Sue-shaming and about mixing original fic and fanfic in communities and archives - that have combined with other stuff to make me want to write about original writing.
So, re: the debate going around about whether AO3 should allow original stuff in with the fanworks:
There are some people who want to keep a wall between original and fan fiction, and want to keep AO3 limited to fan writers. And I can see their point - I, too, am far less likely to read something if it's original: it's harder work to read, less likely to be id-tastic, when I'm in the mood for fanwork I don't want original, and either the average quality of original fic is less, or I simply don't have good enough filters for finding the good stuff with original as compared to fan work. Plus, many original writing communities are not only very different in culture to fanwriting communities, some of them are openly hostile to fanwriting, or to some of the values that my particular fanwriting community espouses.
The problem I have with that viewpoint is that the separation between original and fan work *isn't* a wall. It is, at best, a long sloping gradient with something on it that might be an attempt at a wall that has fallen over in places and wasn't very straight to begin with (and has only been there for a paltry few decades anyway.) The boundary between original and fan work is not a hard boundary. People have brought up historical RPF several times already, but as far as I'm concerned, it's only the tip of the iceberg.
I write stuff that is definitely fanfiction. I write stuff that is definitely original fiction. And I write stuff that, um, I have no bloody idea if it's one or the other.
And the thing that attracted me, as an author, to AO3, is that it's one archive where I don't have to worry if my fanwork is "enough" for it. Is it slashy enough, or too slashy? Shippy enough, or too shippy? Too porny or not porny enough? Too long or too short, not canonical enough, not finished enough, too crossovery, too script-y or meta-y or poem-y to be a proper story, not angsty enough, too much or not enough... on AO3 I can just put everything up, as a proper archive, without having to stress over categories.
I would love if "not fan-fic-y enough" was one of those categories I didn't have to worry about on AO3. And since - *for me* - the most important role of AO3 is to be an archive for fanwriters to universally preserve and organize their work, I want all the edge cases to be allowed; if that means blanket allowing original fiction (and I suspect it does), then so be it. I would, however, support a restriction that every author account must have at least one definite fanwork uploaded, to preserve the archive as primarily fannish and to filter out people who are hostile to fanfic culture. And a rule that any original work hosted on AO3 must allow derivative work.
And, sheerly out of curiosity (and not intended to be anyone's opinion on what should or shouldn't get posted at AO3): Here is a poll about some of those "edge" cases. What do you think, fandom-at-large? Original or fanwork? (And no, you don't get tickyboxes or third options. You must make a judgement! Like archives always make me do!)
( V. important poll under cut )
(I will stop there before poll gets even longer, but for the record, none of these are hypothetical cases - they are all either things I personally have written, or things other people who identify as fanwriters have done that I could point you to.)