An Exorcism

You are a reverend, sent into a dilapidated basement to perform an exorcism on a victim named Erin, who has been bound to a chair. Using tools of faith you must force it to leave her body. During the exorcism, you will have conversations with both the demon and, when it allows her to speak, Erin herself. Through these dialogues and by solving puzzles in the environment, you will work to uncover the mystery of how the demon was summoned and why it has attached itself to her. Your goal is to piece together these clues to discover the demon's true name and learn the method to banish it from Erin for good.