Fragments of Us. The Echelon, #1.5

A Doomed Love. An Inexorable Law. An impending war and buried secrets. Keylin, daughter of Lord Giles, goes from a noblewoman about to be married to the love of her life to a slave, owning not even her own person. The laws of Castrial are binding, and even nobles are not exempt from it. The man who has brought her father to justice is also the man who owns Keylin: Alaric, the Shield of Castrial. Bertram, her erstwhile fiancé is desperate and willing to do anything to save the woman he loves, but Alaric will never let go of Hamin Giles, and Keylin won't leave her family to suffer alone.
Behind the scenes, a war is brewing, friends go missing, and a secret that's been kept from Keylin all her life comes to light. Fragments of Us is takes place partway through Blade Broken and ends just before Blade Reforged starts. It is book 1.5 of the series and not a standalone and hence will not make sense to those who haven't read Blade Broken already.