Okay, the way it worked:
There I was in the Republic of Panama, with my rich uncle, Sam. And one time (after having entirely too much fun with a disease called leptospirosis) I wound up in Gorgas hospital, and after that I had two weeks of convalescent leave. (This was the period that Doyle calls "Our worst Christmas ever.")
So, anyway, while I was home on leave....
Well, back up for a moment. There I was in the Republic of Panama, and all the science fiction books were imported by just one importer, Servicio Lewis, and they only got a new shipment once a month, and it wasn't a great selection. So after reading them all there'd be three weeks or so until the next selection. So, in order to have stories of the kind we liked to read, Doyle and I started writing our own, for each other. (The other choices on base were alcoholism, adultery, and amateur theatricals. Writing science fiction seemed sort of a better choice all the way around.)
.... home on leave, I typed up a story about werewolves. This wasn't really a random choice, we knew about an open anthology with the theme "werewolves." So I wrote a story, then Doyle worked it over, then I played with it some, and eventually we sent it off.
And one afternoon while I was down on the boats, Doyle got an international long-distance phone call from the editor saying that a) she wanted to buy the story, and b) it was 8,000 words too long, could we cut it?
So, we did. The story was eventually published and was the lead story in the anthology. (The two places you want to be in any anthology are either the first story, or the last story. Those are the positions of power. That's where the editors put their strongest works.)
Anywho...from there, one fine day while attending a conference, Doyle was approached by an editor from a packager. You have to understand that packagers are folks who are very much like those annoying folks who come up to you and say, "I have a great idea for a book! You write it and we'll share the money!" Except, packagers really do have the money. And they've already sold the idea to a publisher. All they have to do is find the authors. And they trawl through anthologies and such places looking for young authors who've made one or two sales (so they know they can write on a professional level) and pitching them on writing a fast novel. So, we agreed to do this. I figure it was like an intensive course on How To Write A Novel, working with a real editor, and, as an added bonus, they paid us. In advance. Those books came out from Ballantine, under a pseudonym.
I was still in the Fleet at this time. Doyle was living back in the USA by then.
Then the editor asked if maybe we had something else? So we pulled out a bunch of letters that Doyle and I had written to each other (being at sea makes you a real letter-writer) where we'd been just telling stories to each other in a sorta medieval world. These were titled, in our letters, "Yet Another Scene."
We whipped those into shape as the Circle of Magic series, and the packager loved 'em, and they're still in print. At that point we got an agent. Which wasn't too hard to do with two novels in print and a contract for six more in our pocket.
By then I was out of the Navy and living with Doyle in Manchester, New Hampshire. And we figured that if we were going to be writers now was the time to do it, because otherwise I'd have to find a job. So we took a bunch of stories we'd written in Panama, and which had just been lying there (on Atari 5.25" disks) and cobbled them together into a novel. They'd aged around four years by then, and we'd written eight novels (mostly short YA novels, but still), so we'd had a bit of practice, and we put it together and polished it up.
And I mentioned on the Science Fiction RoundTable on GEnie (anyone remember GEnie?) that we'd just finished a novel. And Patrick Nielsen Hayden (who I'd never met, or even heard of at that point), an editor at Tor, wrote and said, "Don't let your agent send your book to anyone before she sends it to me."
So, he read it, and offered to buy it, but only if we wrote two more books in the series. So, I quickly came up with two more plot summaries, about 250 words each, and Tor bought it. It wasn't published as frontlist, or backlist, or midlist, it was published as an "off-list special." And the first printing sold out in the first month, they went back to press, and that book eventually had seven or eight printings.
So we sold what was the first Mageworlds book, and the two sequels turned into four, then six ... and meanwhile, it was up to our agent to sell books, not us. Which all worked out pretty well. The werewolf short story was never reprinted, but it did turn into the first chapter of a YA horror novel, which eventually turned into a trilogy.
The short story didn't need anything more than a cover letter, and from that point on it was editors asking us, not the other way around. (Something about being Locus Bestsellers with every book we wrote probably had something to do with that.)
So that's why we've never written a query letter.