I may be wrong but what it means to me.. I see the demon as depression or even a more serious "challenge" that's hard to let go or even too comfortable to let go. I really feel connected to the novel, it really resonates with me. The beautiful visuals that are a wonder to look at, the (choice of) ambient/background music that I've been listening to ever since playing it, and the incredible atmosphere that I love to get lost in.
Thank you!