You walk along the Hallway and the Moving Staircases, you see a large portrait that you don't quite recall being there before. The portrait is an enchanted image of people talking and lounging about in a room full of comfortable furniture.

Upon close examination, it would appear that the portrait seems to be hiding a secret of some sort amidst the painted laughter and smiles. But this castle is full of secrets to begin with and full of secrets that really aren't secrets at all, so it's easy to dismiss this portrait as something odd, but nothing more.

Or is there more to this portrait than meets the eye?

In truth, this portrait serves as the doorway to the Prefects' Lounge and is accessible only to the Prefects of each House. The portrait and the people in it will never divulge its secret, though will relay messages to those inside - if there's anyone inside - in the event of an emergency.