I think we're making too much of the concept of "rationalist fanfiction" altogether. A typical fan of MoR would presumably be interested in fiction delivering rationality-related ideas or emotional states; that might constitute (or at least overlap with) a genre, but it certainly doesn't imply derivative work. Neither is the bare fact of setting a work in another writer's world necessarily a genre label; about all you can reliably conclude from that is that the author wants to comment on the original's themes, or to explore implications the original author didn't. Fantasy stories are notoriously ripe with questionable implications, so we could expect the fanfic approach to produce some interesting-to-LW fruit, but it hardly seems like it should be promoted to a defining characteristic. So, what does unify the set of stories we're talking about? Seems to me that it's their themes: empiricism, respect for the scientific method (as opposed to the trappings of science, Michael Crichton-style), and a belief in focused introspection. The use of an existing setting serves to play up the contrast between those themes and the assumptions of conventional genre literature, but it's not necessary, and the themes could work just as well without it. Observation seems to bear this out; MoR shares a lot more, structurally and thematically, with The Cambrist and Lord Iron, or with Eliezer's earlier Sword of Good (both original works), than it does with, say, Harry Potter and the Nightmares of Futures Past. If we're actually looking at a nascent genre here, it's a subset of revisionist fantasy (other exemplars: Gaiman's Problem of Susan; Mieville's Bas-Lag books), not of fanfiction-as-genre -- although I'm pretty sure fanfic-as-genre is a lot smaller than it's usually given credit for, anyway. (Granted, there might be a minority of potential readers who look at MoR or Luminosity's fanfiction.net address and immediately fixate on that as definitive, but that's not a rational respon

I'm not terribly clear about what the assumption is, exactly, and I'm not sure everyone in the conversation has the same referent for it, so rather than say "yes" or "no" to an ill-defined question, let me articulate some related thoughts. * I like the idea of fanfiction where characters who in canon think and behave in muddleheaded ways and ignore what seem like fundamentally interesting aspects of their world instead think and behave clearly and attend to the interesting things. * If done well, rationalist fanfiction can be a great example of that, as rationality is a very useful tool for focusing one's attention on the things that matter. I like that sort of rationalist fanfiction quite a lot. (Which is not to say that I like anything that qualifies as rationalist fanfiction.) * MoR explores some marvelous ideas, it's clever, it has moments of genuine humor and genuine human feeling. The early chapters, in particular, really spoke to me; the later chapters less so. As fanfiction goes, it's probably in the top 10% of what I've read in my life, not that I'm a huge follower of the genre. But it has weaknesses that frequently bug me. As fiction goes, I would be fairly disappointed if I'd picked it up at a book store. I don't care too much about Americanisms vs. Britishisms, though. * I'm vaguely intrigued by the LOR variation -- it reminds me somewhat of the Sundering novels -- and might read it some day when I have more time to spare. Dunno if any of that is relevant to your discussion. If not, feel free to ignore.