Atop the Trees, Beneath the Mountains

When he's called to a distant tower, Esor an Amen believes he's taking an ordinary teaching job. Instead, he finds a dangerous family with ancient secrets...and a dark lord obsessed with him. Lord Corvin stalks Esor through shadow and controls his every movement. Though Lord Corvin is set to marry a lady, he makes it clear there is only one prize he desires: Esor bound in his bed forever. The Dwarven Warlord approaches the port city.
No army can stop him. He seeks a hostage as revenge, and he will not settle for less than Lord Corvin's lover. But there is more to this pursuit than Lord Corvin will reveal. Whoever controls his heart controls the world.(This book is also serializing on RoyalRoad.)