Soul Bound by Ella M. Lee

Arianna Ward doesn’t have a lot to look forward to in life, least of all freedom. She’s spent a year being tortured and bitten as a vampire’s pet, and when she’s sold to a new master on her nineteenth birthday, she’s sure she’s in for another awful year ahead.
But her new master is different. His name is Ren. He has secrets—and plans. He wants to make a fair trade with Arianna, and the offer on the table is her freedom. Ren wants her to complete one task for him, and then she can walk away from the horrors of the supernatural world forever.
And his task might not even be that difficult, because Ren isn’t at all what he appears to be, and he can grant Arianna power she’s never dreamt of before. Power so great that—when this is all over—she might find herself wanting to stay with him, despite the hell she’s gone through.
Author’s Note: This book deals with the topics of violence, rape, suicide, and death. Reader discretion is advised.