In the second book of the Enemy series (which now has an actual series name of Chronicles of the Empire) I ended the book on a tiny bit of a cliffhanger. Someone died. I got some anguished email over that one. But my real regret there is that it took so bloody damned long to get around to book three so I could solidify that cliff hanger.
Beyond that, I have no major regrets over how I've treated characters. And this is probably where I will leave you because my parents moved in today. It is no longer possible to walk through the house without serious risk of bodily injury. So I'm gonna go risk minor bodily injury and go schlep furniture around into some semblance of order. And keep writing this series, wherein, I *might* do something for which I will have to apologize in a future blog post.