the boy from room 205 - Phan

in which...

Dans mother decides to send him to a christian mental hospital after Dans bipolar disorder has become too much for her to take care of and she doesn't want to worsen anything causing him to do the unspeakable. She knows a few of the sisters as well as the over head of the institution and is therefore calm in her decision to send her son there. She also knows that the institution doesn't hate or treat lbgt patients differently and this is suiting as dan is bisexual.

But what does that mean when a certain guy gets admitted and moved in the room next to Dans?
Who is this guy and what happenes the night of the full moon?