Dark Virtue: Book 1: Threads of Ruin by Zee Ghani

She was the evil he was built to destroy. A weapon forged in shadow and ruin. Their meeting was inevitable—a force not even the Gods could contain.

Saviour.
You were a story, a beacon of hope where only darkness existed. A man who only left his castle to kill the evil that threatens our broken world—evil like me, a Nightwalker.
I'd always known we were inevitable, that only one of us would survive. But you enslave me, instead. Bound me to your will. Forced me to protect what you love.
Foolish, Saviour. In a world where survival is betrayal and love is a weakness, you should have known—I'm an evil you weren't ready for.
And when I escape—Your kingdom will burn.

Nightmare.
Your existence defies nature, your golden eyes command terror, and your hands are stained with the blood of Kings. You were supposed to die when we clashed. It was inevitable.
But the shadows are thick, Nightmare and your enemies are gathering. They want to see you fall. They want to see you bleed. They want to see you dead.
But not before I'm done with you.