A Casualty of Wildflowers

Before a prophecy swept him across the seas, Oskar Dahlin was a mortal among corrupt rulers. He lived with one mandate: protect the innocent. Be their sword, and if necessary, their vengeance. He was a Blade of the Assassin's Guild, trained in body and mind. What the royals did behind their high walls was not his concern unless and until their actions spilled into his streets.
Or a young queen steals his heart.
To avoid spoilers, this novella should be read after A Sea of Echoes.