Okay. The Mirror of Erised belongs to JK, as do Tom, Minerva, Lucius, Filch, and Tom's parents. But Minerva's brother is all mine! Mine! Mwahaha. The summary is from the Diadem books by... can't remember the writer, I haven't read 'em since fourth grade.

September 13, 1941

The room was very dark, but a glimmer of moonlight shone through the window. It was almost completely quiet, except for the faint sounds of teachers working in their offices, so that when voices pierced the silence it would have been only too noticeable to anyone listening.

"Come on," someone was saying softly, "someone told me there was something really amazing here."

"That's not the point, we shouldn't be out of bed. Besides, they probably made it up."

"Lucius Malfoy doesn't make things up."

"He wouldn't want you to bring me here. Consorting with Gryffindors- you know how he is about us."

"Don't be a git. You think I care what Lucius Malfoy thinks?"

"Should I?"

"No- look, you don't think that's it, do you?"

If you had been watching you would have suddenly seen a flicker of a lamp, and then the slim outlines of a boy and a girl, dark-haired and dark-eyed, around fifteen or sixteen.

"This?" the girl was muttering. "This is what you brought me to see? You just wanted to get me out of bed." She sounded slightly amused.

"No, really," the boy said. "I'm sure it's something. Let me look close a minute, will you?"

The girl obligingly waited as the boy moved closer to what it now became obvious was a large mirror- beautiful, but only a mirror. But the way he was staring at it made it seem like much more than a mirror.

"My God, Minerva," he whispered, awed, "look!"

"What d'you mean? I don't see anything, except us. Come on, let's go. Filch'll catch us any minute."

"Maybe you have to be alone. There, now look."

She stood there, stiffly, looking into the glass, and then suddenly flinched. "Tom- I don't- I think we should get away from here. There's Dark Magic in this or something. It's not safe."

"What did you see?"

"It doesn't matter, it's not important. I just don't think we should look at it any longer. Come on, let's go-"

"Minerva, what did you see?"

"All right- fine- I saw my brother. He's been- you know he's been dead since my third year. What did you see?"

The boy was looking at the mirror, over her shoulder, as if it contained something stranger and more wonderful than he could have imagined. "I saw- I see my mum. You don't think- maybe they're inside the mirror- maybe all dead people are- inside the mirror- and you break it to get them out?"

"That's ridiculous," she said harshly. "Impossible. Look- there's an inscription- Erised stra- maybe another language. It's not Latin, I think, maybe it's-"

"It's backwards, I think. I show not your face, but your heart's desire."

"It's not real, then." Her voice sounded small and lost in the large room.

"No. Just- your heart's desire."

The girl choked out a laugh. "Why is your heart's desire always something you can never have?"

He smiled. "Is it?"

She nodded. "Maybe we should go."

"I want to look a little longer. I don't- I don't have any pictures of her."

"No, I think we should go. We'd get in so much trouble. Let's- Tom, come on."

He was staring almost blankly into the reflection of his own face. "I'm going to kill him," he whispered. "He as good as killed her."

"Tom, are you all right? I said we should go."

He seemed to snap back from his dream world and find the real one less to his liking.
"Yeah- let's go. Ought to put the lantern out- don't want to tempt fate."

"Or Mrs.Norris."

Tom laughed. "Yeah."

The light went out, and then they did, and then there was only the glimmer of the moon, reflected.