This is something I think about a lot, actually, because I write different subgenres under the same name. And I really don't want to alienate my audience, because, as previously mentioned, the cat yells at me if she doesn't get fed. (I named her after the Queen of Connaught for a reason. Let's just leave it at that.)
On the other hand, it's not like there's any reason in the world to do this gig if one isn't having fun. And fun, for me, includes the ability to mix it up, to do something a little different every time. While I respect the richness of worldbuilding that writers can develop through an open-ended series in one setting, I'm not sure I could do that. (Which is why the Promethean Age stuff makes me so happy. I get to write a series... and I can go anywhere in the world! And play with the same characters if I want to--or introduce totally different ones.
Stroke of genius. If I do say so myself.
So what I try for is a consistency of tone. The narrative style varies, of course--Jenny's hard-boiled voice would be utterly wrong for The Stratford Man, say--but generally whatever I write will have certain elements in common. For example, it's generally emotionally fraught, and I'm as concerned with the character's internal lives as with the "plot." My characters aren't necessarily people you'd want to be stuck in an elevator with (although some of them are truly decent human beings--and some of the decentest do really terrible things. [Matthew, anybody?])
But they have pasts, and they have problems and lives outside the story. They've made big mistakes.
And many of them have pets.
Because pets are nice. (1)
Anyway, I write to be read, and I do want to give my readership what they want. (I want a readership that wants to be challenged, too. *g* It's like any relationship. We all walk in with our own demands, and then the things we're willing to negotiate on.) And of course you can't please everyone, as an artist.
So I think what we do is play to our strengths, shore up the weaknesses, and trust the people who are most in sympathy with our work to find it and love it. And those people--the ones who love it--are the ones who matter. They're the ones I'm writing to.
The ones who think I'm okay for a long plane flight, well, if I can scoop a few of them in to the rabid-reader circle by kicking them right in the squids, that's really nice. But as an artist, as a brand, what I have to be concerned with is the people who already have a bulletproof kink installed that I can hit, reliably, every time. (Tough girls. Personal honor, coupled with divided loyalties--there's a conflict I could read about (and write about) forever. Desperation stands. Refusing the gate. There's a scene in Scardown in which Jenny refuses an illegal order that is one of my favorite things I've ever written. I wrote it when I was halfway through Hammered, and I knew I was working toward it for a book and a half. Man, that bit hits all my kinks.)
Which is why, actually, I'm not overly concerned with bad reviews, especially when it becomes plain that what the reviewer didn't like about the book are the things I loved. Sorry, guys; I may love you as people, but if you don't have the right buttons factory installed, I will never be able to push them, and there's just no use in trying. Much like that Bonnie Raitt song says--
Which is not to say that I don't care what people think. Of course I care what people think. But I'm not going to sell beer to people who like soda pop; so I'd better concentrate on selling the best beer I possibly can to people who already like beer.
Or, to put it another way, 80% of the love comes from 20% of the readers. 80% of the complaints come from 20% of the readers.
These are not overlapping sets.
And this goes for every writer, I think. Figure out what you're good at, and become brilliant at it. Accept that you will not be brilliant at everything. Accept also that this does not excuse you from trying.
(1) Actually, that leads into a nice little digression on writing believable animals. Most writers... kind of suck at this. The thing is, animals are individuals. They have their own personalities and quirks and agendas. There's no such thing as a cat, any more than there's such a thing as a chair. It's this chair, right here, the one I'm sitting in with the scuffed plastic arms and the worn plaid nylon seat. It's that cat, up there, with the slightly sardonic expression concealed behind a veil of innocence.