Black Heart by Ketley Allison

I never meant to become the obsession of a killer.

Kaden Black was hired to kill me.
He’s a scarred ex-soldier with a list of bodies behind him and a decade-old vow of revenge. I’m the key to drawing out the man who destroyed his life – and now I’m under Kaden’s ruthless protection.
Every camera he installs strips away another layer of my privacy. Every order he barks reminds me I’m trapped. But when rival assassins break in, it’s Kaden’s brutal efficiency that keeps me breathing.
I tell myself I hate him. That his dangerous allure doesn’t drown out my survival instinct. That I don’t crave the possessive glint in his eyes when he looks at me.
I’m lying.
As he spirals deeper into obsession, I realize I have a choice to make. Help Kaden hunt down the monsters from his past, or break free and save myself.
But freedom comes at a price. And it might just cost me the one man I can’t bear to lose.