The Border Keeper by Kerstin Hall
My rating: 5 of 5 stars
Set on the border of the real world (albeit not one we know) and in various alternate realms, the relationship between Eris - or whatever name she's known by - and Sethe ebbs and flows depending on what world they're in and how Eris feels about things. There are rules they must live by in all worlds, usually stated when entering a new realm, and many realms rulers (or claimant) are vying for control of all Mklais with shifting alliances and loyalties. There's also a question of whether the border will be breached, and where those trying to are from. By the end we're not sure exactly who or what Eris and Sethe are, except that they aren't what we were told they were at the start. This is a short read, but not a quick one.
eARC provided by publisher.