Michael blogged about the genesis of “The Armies of Elfland” and “The Trains That Climb The Winter Tree,” mentioning that, while the opening paragraphs were written about twelve hours apart, the writing of “Armies” came much later than that of “Trains.” Was anything different about your process or your approach to collaborative writing for “Armies” than for “Trains”?

Eileen: We have a process? We have at least two processes. Michael is a great idea-guy, plus he writes rich, assured prose, filled with dynamic characters vying for the reader’s attention and suggesting a dark underside to the strange world of the story. Right from the start. Michael’s beginnings always terrify me, because they are coherent. Generally, I have no idea where I’m going, and if a story starts to make sense early in the writing, I get worried that the story will be too conventional.

So, in this case, he sent me the beginning of “The Trains that Climb the Winter Tree,” complete with title. It was just a paragraph or two, but it had elves in it, and they came out of a mirror. I thought, “Why is Michael trying to get me to write about elves and mirrors? Is it just to torture me?” I didn’t realize he had a plan, and that it involved a lot more than a mirror and a handful of elves. I also didn’t realize the elves and the mirrors were actually my own fault, tossed off glibly in a moment of whimsy. (Michael explains all this in his aforementioned blog post, so you can get his side of the story there, and the details of his plan.)

At any rate, I thought, however unjustly, “Ha! Two can play at this game.” And I turned his opening paragraph inside out, making the mirrors come out of the elves. In short, I was misbehaved. I did not hear Michael’s anguished scream, 2,827 miles away, when he opened my email, but there was definitely a disturbance in the Force. The next day, I received an email saying, “Now we have two stories.”

I think what keeps the game of collaboration going (for me, anyway) is that it could change at any moment. At some point, Michael would yell, “Okay! We’re done! Don’t you do another thing! I’ll write the ending!” And then he’d finish it and send it back to me with the warning, “Don’t you change anything!” And I would change something.

Now that I think of it, our collaborations were a lot like the part in our elf-free story, “Zeppelin City,” where Rudy is running hell-bent-for-leather through the underground tunnels, chased by the cops, following little glow-in-the-dark markers he has placed there himself, when all of a sudden, he realizes he’s been following someone else’s markers, and he has no idea of where he is.

This is not probably the healthiest way to collaborate, but writing with Michael kept my mind alive and taught me how to plot energetically instead of passively. I have no idea what collaborating with me did for him.

Michael: As I recall, we used my usual method for collaborations: One of us has control of the story for a month to do as much or little as he or she cares to and then has to surrender it to the other. Who then has license to make any changes whatsoever—including restoring material the other removed. Ultimately, the person with the stronger vision of how the story should go will prevail. In this case, it was Eileen. In “The Trains That Climb the Winter Tree,” it was me. But I found the endings for each. That’s one of my talents: If a story is good enough, I can figure out how it wants to end.

Will there be any more stories of elves and mirrors or any more collaborations?

Michael: There was no thematic reason for there to be two elves-and-mirrors stories. But I had written a lovely opening to a story, with elves coming out of the mirrors and when I offered it to Eileen, she immediately changed it to a very different story opening with mirrors coming out of the elves and then fell in love with the new version. So the only way to get the story I’d originally envisioned was for us to write them both. It’s unlikely, therefore, that we’ll extend the franchise.

As for other collaborations, that’s entirely up to Eileen. I am the most easygoing and cooperative of men.

Eileen: No more elves, if I can help it. And probably no more collaborations, as we are hoping to remain friends. Instead, Michael has sent me, every so often, a very detailed description of a story he has decided I should write, along with the suggestion that writing it will be very good for me, and will take only four hours of my time. He has also said “These are not collaborations!” and suggested that if I link the finished story to him, he’ll deny all knowledge, just like the government in Mission Impossible. So my lips are sealed. I cannot guarantee, however, that—no matter how much readers may prefer never to read another story of the deeply conflicted Swanwick-Gunn elves—Michael will not someday take it into his head that he should make me write another damned elf story, and I may be powerless to stop him. I may not even recognize it as an elf story until it’s too late.

Michael: That’s actually not a bad idea. I’ll give it some thought.

From the opening paragraphs of each story, it seems like you both had a clear and consistent vision of the nature of elves. Whose elf stories have you enjoyed? Were they all in the same cold, cruel camp of elvish characterizations?

Eileen: I enjoy Michael’s elves in stories that we have not collaborated on, because in those stories, the elves are not torturing me. Michael’s the one with the consistent vision of elf-nature, and he takes a very dark view of the elven psyche. He’s sort of the anti-Tolkien: His elves are not tall, wise, silver-haired elders. They’re more Icelandic elves, and they do not have your best interests at heart. Of course, his humans often don’t have anyone’s interests at heart but their own, either. My current favorite is his story “A Bordello in Faerie,” which is in his collection The Dog Said Bow-Wow, from Tachyon Publications.

Michael: My vision of elves is shaped by years of reading in mythology, where they’re consistently portrayed as being soulless, capricious, and without conscience. Their value seems to be in holding up a steely and pitiless mirror to the human soul. Poul Anderson’s novel The Broken Sword and Sylvia Townsend Warner’s collection Kingdoms of Elfin are big favorites of mine, and the elves of both are cold, cold, cold. Tolkien’s elves have more than a touch of that too.

What was behind the trolls and reflexive behavior?

Eileen: I don’t really know: they don’t have a very substantial role—mostly they loom, holding clubs or books. But not knowing the answer has never kept me quiet before, so I’ll go ahead. I thought of them as being sort of meat puppets, synthetic creatures that have a certain scripted conversational ability, perhaps derived from humans they have eaten, but no emotional capacity at all. Trolls of legend are generally large and strong and dimwitted. These particular trolls seem to be violent but without any particular malice, which is what makes them, in my opinion, more than a bit creepy. Mean and violent, that seems comprehensible, but disinterested and violent is subtly more disturbing. It never occurred to me to ask Michael what he thought the trolls’ psychological underpinnings were, and I doubt he would have told me if I’d asked.

In some way, perhaps that’s probably an indication of our process: Michael might know what’s happening, but he doesn’t tell me for the longest while, and I certainly don’t ask what’s going on, because I think the clues are there in the text, and it’s my job to figure them out. Michael won’t tell me, anyway. But I’m pretty sure he knows.

Michael: Half of it was just for the weirdness of it. But also, the trolls were essentially slaves and so not responsible for what was done to the human race. If they were conscious beings, the story would have had to find a just way of dealing with them—and that would have distorted its shape. I believe that the elves too were ultimately revealed to be non-sentient, though at a much more high-functioning level. Simply because neither Eileen nor I wanted to have a happy ending involving genocide or racial enslavement.

I won’t explain to Eileen anything that hasn’t already been written because she has a perverse streak and will immediately set out to subvert it. If I don’t tell her what I have planned, she can’t prevent it.

All this stems from the fact that Eileen is at heart a trickster. If I could only get her to understand that, it would double her productivity overnight.

Euclidean geometry and elves—how did that come about?

Michael: Well, the elves came out of the mirrors originally, and objects in mirrors are stranger than they appear. But also, the point of fantasy is not to take elves, queens, trolls, knights, and the like, and arrange them in new patterns like so many action figures. It’s to create impossible worlds of such surpassing strangeness—and beauty, too—as to tell us something about our own. By contrast, if in no other way. But I think we achieved something meaningful here too.

Eileen: The elves came to our world from another dimension, and they are basically two dimensional, so when humans rotate or move quickly in three dimensions, with curving motions, the elves can’t actually see them. It made sense to me, because, although I did very well in high school geometry, I have never really understood vectors. I don’t see mathematics well in three dimensions—perhaps I have elven ancestors. At any rate, the geometry underlying the elves makes this a science-fiction story, in my opinion, rather than strictly a fantasy story.

Any news or projects you want to tell us about?

Michael: I’ve just finished and turned in to my agent my latest novel, Chasing the Phoenix. This is the second book-length adventure of post-Utopian confidence artists Darger and Surplus, and in it they accidentally acquire armies and conquer China. These things happen to them. And Eileen has a new collection in the works, but I’ll let her talk about that.

Eileen: I have a new short-story collection, Questionable Practices, coming out on March 18, from Small Beer Press, and I’m hysterically excited about that. The book was designed by the very talented typographer and book designer, John D. Berry, who is also my husband, and who designed my previous two books. Also, I’m hard at work on a novel. Yes, Michael gave me the idea for it, but he thought it was a short story . . .

Michael: It could have been a short story, too. But I told Eileen it was. So of course she had to turn it into something completely different.