that's interesting. I like that idea, but there's also the "I am"-"angels are" and a few other references that make me think that the entity is a fallen angel-like creature, but I also like the fae theory. And associating it with owls makes a lot of sense, because 1) Owls have large eyes and good vision, which would tie into the whole "stealing your eyes" thing 2) There are a few pictures next to the quiz with owls. I like your theory!
Another thing I noticed: There is an ending called "Friend". I was aware of it at the time(because of the credits) but I haven't actually seen the ending screen. Someone else in the comments got that ending and it said that the entity is planning to transform the player. The existence of the "Friend" implies that there is a difference between it and "Candidate".