I'm the first to admit that there's sometimes there's a fundamental disconnect between editors and the marketplace. Stories are legion about books that have been rejected dozens or even hundreds of times, only to go on to bestsellerdom.
One specific area where we editors need some training, I think, is in our openness to books that cross subgenres. For example: mystery + horror; supernatural + thriller; hard-boiled + cozy; environmental + amateur sleuth; futuristic + police procedural. A lot of people are writing these kinds of books, and my reaction upon seeing them is always a slight frown. The wheels start turning: How am I going to market this? How am I going to edit it, what with very few examples to guide me in how to make it?
Yet--I always read the manuscripts, because some of these books sell very well indeed. Think Iris Johansen. J.D. Robb. The Twilight series (suspense, romance, supernatural). As I write this, the latest Sookie Stackhouse book is firmly entrenched in Amazon's Top 10.
And I do want to sign a series or two that combines subgenres, preferably one that would appeal to both adults and teenagers. So I keep looking for them and hope that they find their way to me. At conventions and various places online, I hear established agents, writers, and editors talking about how hard it is to get contracts for these books, and advising aspiring writers to write something more "traditional" to break into the biz. It's not bad advice at all; and yet there are so many indicators around us that there is a market for these books. The frustrating thing for writers, I think, must be hearing people like me say that we want something "new and fresh," and then have us dismiss something as "too different" or "won't sell." I wonder what Charlaine Harris's editor and agent said the first time they read a Sookie Stackhouse book...
Anyway: Based on my reading of the marketplace, today I think I can spell out what a cross-genre book should be in order to have a ghost of a chance.
1. KEEP IT SEXY. That seems to be the watchword for this blended genre. Many of the books seem to have a low-level charge of eroticism that runs through them. I'm not saying to include a lot of explicit sex, but certainly these books move beyond the cuteness of romance and into the more physical side of things, with passions, achings, and longing that are somehow thwarted. And the sexiness is more on the dark side--forbidden loves, acts that maybe go beyond the typical lovemaking techniques in which we boring mortals engage. So many of these books are a walk on the wild side, a way for the reader to explore an unexplored area from the safety of his or her reading chair.
2. KEEP IT ON THE EARTHLY PLANE. With regard to the books with supernatural/horror elements, the dark characters (vampires, et al.) tend to walk the earth and try to "pass" as human beings. This grounds the book in reality and also writers some fun. On the lighter side, the behaviors and habits of the supernatural folk can be used to point out some of the foibles of humanity; on the darker side, the darker beings can stand as symbols (of a sort) when humans mess with things they don't necessarily understand. In either case, there's something about having the book grounded in humanity that makes it more "believable" and acceptable to the reading public.
3. THINK GOOD VS. EVIL. The struggle of good against evil has been around since Cain and Abel (or, even before that, Eve vs. the Snake). It really is one of those plotlines that almost always works, and I'd argue that it really helps ground things in a cross-genre book. Now, I know that in recent posts I've argued for making the villain or antagonist something beyond a one-dimensional evil being; but I think that in cross-genre books, you can have really bad/evil creatures/beings and set up your protagonist as the foil. Battles between the good and the bad just work inherently, I think; they set up conflict (a key driver of any plot), a race against time (always good for suspense), the need to outsmart the baddie.
4. POSIT AN ALTERNATIVE REALITY THAT SOLVES A HUMAN PROBLEM. While we all have our own individual problems, I think it's probably safe to say that as a race we humans share certain frustrations. First, we get older. Second, our lovers and children drive us crazy. Third, money is almost always limited, and we never have as much as we'd like to have. Fourth, we have a sad tendency to put on weight if we don't watch ourselves very, very closely. I think that the successful cross-genre books that I've seen posit a reality in which at least some of these problems are overcome. Vampires remain youthful, and due to their immortal nature amass great wealth. We want to be able to read other people's minds, but can't; but psychic beings can, which I think offers the reader a nice sense of wish fulfillment. And so on.
5. DON'T MAKE IT TOO SUBTLE. I think cross-genre books have to hit you over the head in order to work. Too subtle, and readers think you may be playing games with them, or that you don't have the courage to make everything work. That's why, after teasing the reader with some unanswered questions for a few chapters, you do have to come right out and reveal that your protagonist is a psychic, or an alien, or a werewolf, or what have you. Look at the Eve Dallas books; in many of them, the year of the action (2059, 2060) is established on the first page. There's something cinematic about the best of these cross-genre books; they're like being thrown into a world that's similar to our own, and somewhat recognizable, but clearly different. I think readers of this genre love that escapism. They're not forced to learn a whole new geography (a la Dune and other science fiction), but rather can just sit back and watch vampires take over New Orleans. In other words, good books remember that they're escapist and don't make the readers work too hard.