The Emperor's Agent was part of the Historic Fantasy StoryBundle book promotion I recently participated in. It is both an alternate history Napoleonic spy adventure and part of a larger millennium-spanning series about a group of Companions who are reborn together again and again to re-live their fellowship at key points in history. At least, that's the understanding I was able to pick up from this book and a blurb-level familiarity with the rest of the series.
Elza, the protagonist, is a courtesan, working her way through several personal alliances among the movers and shakers of revolutionary and Napoleonic France, and cast into considerable personal peril by the shifting politics of the time. Employed as an agent by one party, she betrays her employer at great risk for the sake of personal loyalty to the Empress Josephine and so comes to the attention of Napoleon who takes her on as his own agent. Among preparations for an invasion of England, she hunts for a spy who is leaking secrets to the English as well as getting drawn into an entirely different international struggle involving ceremonial magic.
The writing is enjoyable and smooth, and--to someone like me who is generally familiar with the era but not with the details--has a solid air of historicity. Despite the fantastic elements, this story will appeal most to those who love the minutiae of armies and battles and the comradeship of soldiers. The central plot seems to me to be the military drama and the question of whether the spy will be uncovered in time--as well as whether the identity of that spy will be unwelcome evidence of personal betrayal. If you thrill to the thought of a chapter describing Napoleon's elite staff playing table-top battle simulations complete with mini-figs and dice rolling, this is your book. Around that, we get the domestic drama of Elza's past affairs (both in this life and previous lives) with some of her military comrades, spiced up with several explicit erotic enounters.
This last element positions the book for a fairly specific target audience. To me, the erotic scenes felt forced and intrusive, but I'm not really in that specific target audience. Another way in which the story missed for me (and this is very much a matter of individual personal taste) was that, despite the focus on a female protagonist, it was very much a male-centered story. I'm not even sure it managed to pass the Bechdel-Wallace test: the only two scenes in which Elza is interacting with other significant female characters are entirely about romatic connections to male characters and the complications thereof. For the most part, other female characters are positioned as rivals or obstacles, not as friends or allies. Overwhelmingly, the social dynamics of the book are about Elza's comradeship with the male characters, whether as a lover, or as a comrade-in-arms, or taking up a male disguise to be a man among men. (This is echoed in some of the hints of past lives when she had been born into a male body.) Having the authorial word that Elza is bisexual, I'd gone into the story expecting a bit more female presence. (I don't mean by this to erase her bisexuality. Only to note that one passing, vaguely-salacious comment to a woman didn't fulfill my own emotional needs as a reader.) Though I suppose, when you think of it, that there's a certain bisexual element in that Elza has erotic encounters with men both as a woman and when in disguise as a man.
I don't mean to dwell too heavily on the sexual content of the book, but as a reader's advisory if falls in the category of, "If you like this sort of thing, then this is the sort of think you may like."