I don't like pat endings. Predictability is an enemy, and I try to fight against it in each of my stories. If you're expecting a "pretty pony party" (borrowing a phrase from Lemony Snickett) at the end, then don't read my novels.
So how do I handle endings when I want to preserve characters for a potential serial, rather than just killing them off in a "surprise" ending?
I'm struggling with this. A bit. Right now I'm working on PURSUING OTHER OPPORTUNITIES, and am sorely tempted to kill off one of the two heros (one of whom is already showing definite "bad guy" tendancies. But I'd also like to preserve those two characters for one more tale -- hence, a quandry.
Of course, avoiding a pretty pony party, doesn't mean the main characters have to die -- I get that. But then they shouldn't get what they want, at least not all of it. And there needs to be a few additional twists to the tale that seem to come out of left field to spice things up.
So here's a confession -- I love misleading readers. And while there tend to be multiple misdirections in most of my books, there are also clues that, if not ignored, will take the reader in the right direction, too. As a reader, you have a chance to "figure it out", but I'd be disappointed if many people successfully did so.
In my stories, sometimes the identity of the "real" bad guy is a surprise. Sometimes the bad guys win. Sometimes the good guys are corrupted and go bad. And sometimes the good guys do get what they want -- at least a part of it. But never all of it.
Just like in real life.
Here are a few examples:
In LEVERAGE, the identity of the bad guy is a suprirse. In INCENTIVIZE, at least one of the bad guys "wins." In EMPOWERED, the good guy is corrupted. In DELIVERABLES, again, the identity of the bad guy comes out of left field.
So if you're looking for that pretty pony party ending, better stay away from my novels. If you enjoy a cynical hard edge of reality, however, give one a try and see if it leaves you surprised.