My Hired Bodyguard Is the Original Vampire

Isabella, heiress of the Sterling family, has kept Louis close as her bodyguard for three years, but she finally resolves to end things with him. Her plans take a sharp turn when she discovers her fiancé Carl betraying her with her illegitimate sister, and she breaks off the engagement. Hoping to move on from her old life, she soon finds herself pulled into Louis's mysterious blood feast, and their history begins to feel unfinished.