Fierce Vow by Monica Kayne

ALYONA
Leonid Kozlov. Bratva royalty. My brother’s best friend. And the man who shattered my heart.
I’ve spent years trying to erase him from my memory, but when my life is threatened, Leo crashes back into my world, looking as sexy as sin and appointing himself as my personal protector.
I don’t want his help, but fate has different plans. When I wake up on a yacht in the Mediterranean having to pose as his fiancé, I’m caught in the crossfire between my pride and lust.
Leo may command my body, but I’ll never surrender my soul.

LEO
They say there is no redemption for men like me. It doesn’t matter because I already live in hell.
Alyona Nikitin was the one good thing in my life. I wanted to give her forever, but that would mean signing her death warrant.
I never truly let her go though, not really. I watched over her, kept her safe, chased away the losers that dared dance around my angel.
But now that a powerful enemy is after her, all bets are off.
She may despise me, but I won’t lose her a second time. I am going to take what’s mine, once and for all.