It had become night, and Luna was sitting in the darkest corner of the Gryffindor Common Room. She was holding a pen in her hand and staring down at a sheet of paper, which was perfectly smooth. There was no moon, and the only light came from a single candle, perched on top of a table on the opposite side of the room, and this only let out a small, wavering, glinting light, so it was almost impossible to see anything at all.
If you could see something, you would have seen that the pen in Luna Lovegood's hand, was, in fact, quivering slightly, much like the candle. Luna's face betrayed no reason as to why the pen was quivering, since it was as smooth as the piece of paper, and smiling calmly.
Indeed, it would have been almost impossible to guess that Luna Lovegood was at that moment completely and utterly terrified. Except that the pen was shaking.
Suddenly, the fire in the burst into life and a figure crept down the stairs, crossed the room and slipped out of the portrait.
Luna's smiled widened further, and suddenly the spell was broken. She pinned the list to the wall and was gone, luckily in the opposite direction to Martin McGorthy, the Gryffindor, who had just gone out on a typical Gryffindor mini adventure, involving dancing radishes and hot cross buns.
And the candle went out.
The next day found the members of the DA clustered in groups, waving perfectly smooth pieces of paper around and talking in quiet voices.
"I wish," said Herbert Bell, "that I knew how to do that spell. Look – crush it, crumple it, folded it, and then when you undo it again you it's completely smooth! It's amazing! It would have saved me all that trouble with Snape as well."
"Have you even looked at what's on the sheet, Herbert?" said Hermione Granger, with a perfunctory sigh.
"I was just about to, actually." He said, opened it out and glanced down at its contents, folded it again, looked up and said, "Looks all right to me."
Then he slowly looked down again, and unfolded it, very, very slowly.
"Good morning, Mr Bell," said the little face on the sheet, "I am your Rota."
Mr Bell screamed (girlishly) and fainted.