57 Book(s) Related to unbreakable vow

When Lena Vale's father dies, he leaves behind nothing but debt — and not the kind any solicitor can settle.
Bound by an ancient blood contract she never signed, Lena is given seven days to present herself at Ashveil Manor, deep in the shadow realm of Veth, and give one year of her life in service to Lord Dorian Ashveil — the most feared vampire in a world she didn't know existed. She arrives under protest. The estate, apparently, listens.
Dorian is nothing like what she expected. He is cold, yes — centuries old, commanding, and devastatingly careful with everything he allows himself to feel. But he is also unexpectedly honest. And he stands when she enters a room, every single time, as if she is worth the gesture.
Lena tells herself it means nothing.
She is wrong.
As the months pass inside Veth's eternal dusk, the line between captive and chosen begins to blur. But darker forces are closing in — a rival clan with a weapon that runs on Lena's blood, a secret her father sold that could destroy everything, and a choice that no contract can make for her.
She came to Veth to pay a debt.
She may stay for something far more dangerous.
Crimson Vow is a slow-burn vampire romantic fantasy for readers who like their heroines fierce, their heroes worth the wait, and their love stories earned one impossible moment at a time.

"So I was just a game to you, Angela?"
"Everything they said is true... I got close to you because of the bet."
Years later, high school betrayal ignites a deadly adult contract.
"This isn't a negotiation, Angela. I want your body, and I'll give you a price. That's it."
"Angela Jones. Once untouchable. Now sitting in front of me, begging."
"You're staying here starting today... your life isn't yours anymore."
Angela Jones is on the rise in Hollywood when a scandal destroys her career. Fleeing to Santa Barbara to escape the chaos, she runs into Aaron Carter,the man she once framed and ruined.
Aaron isn't the boy she remembers. He's a cold, calculated billionaire now, with only one goal: revenge. Using absolute control, he drags Angela into a dangerous game where every past sin and secret is laid bare. From betrayal and heartbreak to a binding contract that leaves her life under his command, Angela must navigate a world of power, desire, and ruthless retribution.
In the end, she must choose: fight to reclaim her life or surrender to the man determined to ruin her... and maybe, the only one who can save her.

Lyra is exposed to the horror of war, torture, and savage treatment from the brutal Alpha King, Ryker Ashbane, who kills her parents as payback for the death of his parents and pack. Things take a turn when the moon goddess blesses her with her fated mate, who happens to be the same man who has vowed to torment her.
Lyra is faced with challenges that resurrect a power core she never thought she had.
Her newfound powers brandish her and seal her thirst for blood and vengeance, but the moon goddess has something else in store for them.
In a twist of fate, they are faced with a horrifying truth in this game of power. But for Lyra, the wounds cut too deep.
The fierce Alpha is torn and is on a quest to win her heart. Sacrificing his life for her, will Lyra give him another chance?

Brie planned the perfect night to give herself to Jeff—the man she loved, the man she trusted. But one moment of mistaken identity shatters everything. In the dark, she surrenders to passion… only to discover the man in her bed isn’t Jeff but his identical twin.
Now, one night threatens to unravel her relationship, her heart, and everything she thought she knew about love.
Was it an unforgivable mistake—or something deeper she’s afraid to admit?

"I'm pregnant, Xarion."
He doesn't even look at her.
"Abort it."
Four years later, she is no longer the wolfless girl who once begged for his love.
She is a mother. A warrior. A woman who rebuilt herself from the ashes he left behind.
And she has no intention of ever belonging to him again.
Until fate brings them face to face.
"You belong to me, Megan," Xarion growls, backing her into the shadows.
"Not anymore."
But this time, Megan is no longer the one with everything to lose.
He doesn't know she was never wolfless.
He doesn't know the truth behind the prophecy that forced him to push her away.
And he has no idea their twins are alive.
Now, as enemies rise and secrets begin to unravel, Xarion is forced to confront the truth: that the woman he broke is the only one he cannot live without.
He let her go once.
This time, he'll fight fate, enemies, and even himself to win her back and become the man she deserved all along.

"I'll pay off Derek's debt and guarantee his protection from the Rogue King. In exchange, you sign a contract agreeing to be mine."
"Yours?" I step back, my ass hitting the edge of his desk. "What does that even mean?"
"It means you move into my estate. You act as my mate in public. You fulfill all the duties of a Luna. And in private... you belong to me completely."
"You can't just... I'm going to be your stepsister in three months!"
"Which makes it even more interesting, doesn't it?"
I loved Derek Savage for six years, believing he'd be my mate someday. When one reckless debt threatens his life, it leaves me no choice but to beg his older brother, Reign, for help. Reign's deal is simple: he'll pay Derek's debt. In exchange, I become his. For six months, I belong to the one man I should never want, my future stepbrother, my Alpha, my forbidden craving. And the worst part? Every time he touches me, I stop caring about right and wrong.

She needed a job.
He needed control.
Neither expected to fall apart for each other.

Elena Rivera is a Brooklyn-born fighter working two jobs, caring for her sick brother, and doing everything she can to survive in a city that swallows girls like her whole. When a fiery encounter with New York’s most ruthless billionaire unexpectedly lands her a high-paying assistant role, she’s thrown into a world of power, luxury, and danger she never asked for.

Adrian Drake is cold, brilliant, and untouchable—a man who built his empire from nothing and trusts no one. Especially not the beautiful woman with sharp eyes and a stubborn heart who now sits outside his office.

What begins as a tense business arrangement spirals into something deeper, darker, and more dangerous. Secrets unravel. Enemies close in. And when emotions cross the line, both Adrian and Elena must decide:

Is love worth risking everything when everything is what you stand to lose?

Genre: Contemporary Billionaire Romance.