Every year on the day term began, after the Sorting Ceremony and before the feast started, Albus would give a brief speech from the owl lectern. Usually, it was the same old thing: reminding students to obey school rules and stay out of the Forbidden Forest.
Students below fifth year had to return to their common rooms before nine at night. They could do homework or throw parties in the common room, but there was no such rule after sixth year, because they were about to become adults and no longer needed to follow "children's" rules.
Pomona stood on the moving staircase, waiting for it to turn toward the platform she wanted. By then, all the castle's lights had gone out, and the portraits had fallen asleep rather than staring at her as they did in stories.
The irises in portraits did not move as living people's did. It was merely that when the viewer changed angles, the iris and pupil seemed to shift from their original positions. It was an illusion, just as portraits with perspective effects exploited visual illusions. The apparently three-dimensional figures in a painting occupied only a two-dimensional plane; their sense of depth was created by light and shadow.
Soon, the staircase stopped moving. Though she was wearing the Invisibility Cloak and no one could see her, she still ascended with graceful poise.
It was not a Full Moon tonight, and the thick clouds let through very little light. Still, once her eyes adjusted, she could make out some things. So when she arrived before the tapestry of the Troll clubbing Barnabas, though she could not see its pattern clearly, she knew she had arrived from the tapestry's general outline.
Not only Dumbledore's Army, but even the House-elves and Filch knew that the Room of Requirement