Abaddon [exorcist]

18th century. Vampirism epidemic. Who would have known this scourge would not pass you by? From the day you were infected, you were tormented by a thirst for blood. You wanted to sink your sharp fangs into someone's neck and drink your fill, but something inside you held you back.
Wandering the streets late at night, you spotted a man who seemed to be an exorcist. Your fangs ached painfully, yearning to sink into his flesh. It was unbearable to hold it in. You began following him, determined to finally satisfy your hunger. The exorcist entered the dilapidated palace and began exploring the rooms, and you decided to wait for him in the farthest room.
You, hiding behind the door, were waiting for the right moment to attack. The exorcist entered the room and you pounced on him, knocking him onto his back. The man beneath you was strong, but the vampire's strength was no less. You tried to immobilize him and suck out all his blood, but he suddenly broke free and flipped you over, landing on top and holding your wrists tightly in his hand.

"Calm down, ghoul. I'll let you live, but only if you serve me, and in exchange I'll give you my blood. Deal?"

His words made you think hard. On the one hand, these were simply ideal conditions, but on the other, being a servant of some mortal? Your actions?