SFRB Recommends #88: A Conspiracy of Whispers by Ada Harper

For Olivia Shaw, the danger of her assignments as a deadly Whisper agent is matched only by that of her hidden status: Liv is one of the caricae, extremely rare women capable of bearing children and therefore controlled by the Syndicate’s government. When her handler sends her into the Quillian Empire, her mission is complicated by stumbling upon a kidnapping in progress.

Liv is drawn deep into political upheaval when her hostage is revealed to be the infamous Red Wolf, Galen De Corvus, brother of the Quillian Empress. Worse yet, he is an altus, more sensitive than most to the pheromones of caricae. If he realizes what she is, he could expose her secret to either government and doom her to a life as breeding stock.

Quillian nobleman turned operative Galen never planned to involve himself with a citizen of the cold, cruel Syn, but Olivia entices him more than she should. As they work together to protect his royal sister from a violent coup, the passionate bond between them proves to be more than mere biology. And Liv must decide if that bond is worth dropping her guard for both an enemy and an altus.

Olivia and Galen are a good couple: he's a patient sweetheart and helps ground her. She, on the other hand, challenges him to look at the world in a different way than he is used to. Olivia has plenty of agency despite her disadvantages, and her guardedness makes sense.
The secondary characters (Galen's sister, her spymaster, two other caricae, Olivia's caretakers, and a cat named Plan B) leap off the page. I never forgot who anyone was or what they wanted. Their motivations clash, and resolving those is not a simple matter.
Well-drawn factional politics dominate this book. Add in clear action scenes, biopolitics, and romantic elements, and we have a multifaceted story that I'd recommend to any science fiction fan. There's a lot to explore here.

This recommendation by Lee Koven
Book site: Ada Harper / Amanda Hackwith romance