The Queen and her Brook Horse — Amalia Dillin

Before Arianna met Bolthorn, Signy, Queen of Gautar, struck a bargain with a brook horse.

A princess sent to marry a cruel foreign king, far from home, friends, or aid, Signy must find a way to protect herself and her people. But brook horses are fickle creatures and their magic is wild at best; if Signy cannot keep her promises, it will cost them both--and the blood that's spilled between them will be the least of it.

This Orc Saga prequel novella should be read as book 2.5 in the series.