_The Magpie Lord_ and _A Case of Possession_, by K.J. Charles
These two books are fantasy novels with a mystery/action plot and a gay romance theme. (I think I can blame haikujaguar for this one, too. I know she was tweeting about the author, though I forget who told me the first book was on sale, which is why I snagged it.) I found the first book, The Magpie Lord, engaging from the start: I hadn't even decided that was what I wanted to read next, but when I brought up my Kindle app, it opened to the first page and once I started I didn't want to stop. It's fast-paced and leaps right into the action, with one protagonist, Lord Crane, under the influence of an unknown curse, trying to kill himself. It's set in fantasy-19th-century-England, with magic as a quasi-secret: not widely known about in England despite the practitioners, but common knowledge in China. Crane had been living in China for the last 20 or so years, and so looks for a magical solution to what appears to be a magical problem. He finds Stephen Day, and then we have a lot of plot about Day helping Crane and then they try to unravel who was trying to kill him and why. There's a fair amount about Day and Crane's background. Crane is an interesting mixture of ruthless and just. He was exiled to China by his monstrous father, who was protecting his even more monstrous brother. The latter two are both dead at the book's outset, and Crane is expending considerable effort trying to right their wrongs as best he can, despite wanting nothing more than to go back to China, where he was a trader, smuggler, and occasional thug. Stephen Day reminds me of Maturin from the Aubrey-Maturin book, as a small, exceedingly dangerous man, with a keen moral sense. They make an unlikely but endearing couple.
The romance is more of a subplot than main story, and more erotica than romance. The sex tends towards consensual BDSM. But there's quite a lot of story that has nothing to do with the relationship between the leads.
I found the novel's climax rather too by-the-numbers and forced; it didn't feel as well-constructed as the first two-thirds of the book. The abilities and limitations of magic are never clearly established and the mystery's solution, while reasonable, isn't one either the readers or characters had sufficient (in some cases, any) clues to derive.
So it starts off as a 9 and ends as a 7 for me -- I'll average it out to an 8.
The sequel, A Case of Possession, didn't engage me as much as the first. Also, I was disappointed by the author's choice to drop Day as a viewpoint character and switch to Crane only. (I find single-viewpoint romances uniformly less enjoyable than dual-viewpoint). That said, there's more romance (which is a plus for me) in addition to sex, as well as another mystery/action story. It's solid, and good enough that I'll read the next, but gets a 7.