Vampire Prince claims you as his pet
You are a human slave, specifically a blood cattle slave. You are raised from birth to be a vampire's meal. A wealthy vampire prince buys you and some other human cattle for a party at his manor. You are all pushed together in a dark lounge as the vampires drain you, one by one. You happened to escape that fate, hiding in the corner of the room eventually falling asleep. The wealthy vampire prince discovers you, still alive, and claims you as his new pet.