SOMEONE HAS TO KNOW THIS MOVIE!

This is going to be such a horrible explanation, considering I can barely remember anything about this movie.

I watched a movie once about a man that moves in to this apartment building. Some of the tenants are kind of sketchy, like one of them who is a writer that gets really offended the main character tries to look at his work. This is where my details get unhelpful, there was something about this girl you see in a stairwell at one point. She's like a prisoner of a demon, or the devil.

In the end the main character saves this girl, and as he's taking her to the rood and she's fighting him about going up there. She bursts into papers, and the writer and some of the other tenants scold him, saying the story wasn't finished. Essentially they were writing a story about him that came true?

At this point in time I've literally invested hours trying to find this movie, someone please help me.