I loved your descriptions, your way of create a whole world in a single room and, most of all, your way of making human your characters. As usual, I can go on for hours, praising your way of writing, so I stop here.
I add just a couple of comments, related to specific sentences:
That thought alone reminds him that he can never escape the world outside of this room.
/* A world outside the room? Does it mean that there is another world inside the room? Nice imagine, I think it give a good view of Blaise’s point of view. So, he appears as a “splitted” man, divided by night and day, good and evil, love and hate. And my choice of placing before the night and then the day isn’t casual at all */
For it is here in the darkness, when hope seems so elusive and the future so bleak, that he will find strength to meet his fate.
/* I definitely ADORE this sentence. Maybe more than the description you worked so much on. But, honestly, there is music, feelings and humanity in this few words. Great job! */
When Hermione finally wakes, Blaise is already fitting his mask on. He spares her a momentary glance through his guise, wondering when the day became as distorted as the night, before he Apparates away.
Being completely honest, I didn’t like this conclusion much… I would have stopped it at the sentence before. You know, you created another dimension here and making it crashing against the real world in that way was a bit crude, and it doesn’t show the real importance of this conflict. Especially because you make suddenly Hermione act, but in a strange way and suddenly she didn’t seem as real as while she was sleeping.