A Friend or Foe..?

Not too long after his arrival to the hotel, Charlie and the others are curious on learning more about Alastor, seeing that it'd be the best thing to do since they're all going to be working together. But everything starts to change when a former shadow starts popping up throughout the hotel. Of course, Charlie catches onto this, and soon starts to investigate. Alastor also catches on, but he isn't too eager to be involved. Who are they, and perhaps, do they having something to do with the hotel? Or better yet, Alastor?