Disclaimer: I don't own Buffy the Vampire Slayer, Supernatural, or the Quantum Mirror from Stargate SG-1.
Note: One-shot. Setting for Buffy is post s7 by several years and doesn't follow the comics. For SPN, it's in season 4. I'm thinking about doing a prequel or follow-up story for this, but I'm not sure. Tell me what you think. It was very loosely inspired by my Heavenly Bodies universe (3-way-crossover): fanfiction (space) .net/s/7586755/1/Heavenly_Bodies

"The Grass is Always Greener"

A cloth, yellowed with age, had been draped over it, but Dawn could tell from its shape, the point of its top, the tilt of its bottom, that the mirror was large. Nearly her height. If it was actually a mirror at all. For all she knew, it was an empty frame, the glass broken out long ago. Or maybe it was just what it appeared to be, a flat rock covered with a sheet.

There was a very simple reason why she'd never looked beneath the cloth: she'd been told not to.

Ok, so maybe Dawn didn't always do what she as told. Scratch that, she rarely did what she was told. In fact, one could argue that telling her to not do something was the only surefire way to make sure it was actually done. Dawn was more than willing to own up to the fact that she had a problem following orders, especially her sister's.

But the way Buffy had looked at her when she'd made the command…

Dawn stepped away from the mirror, glanced the rest of the small underground warehouse. Poor lighting, shelves of warded boxes and dangerous tomes; it was an extremely lonely place. One Dawn didn't prefer to visit often, especially not without a buddy. Yet, here she was, by herself, without protection. The facility was owned by the late Council, and such a secret storage area that even the few Watchers remaining in the world didn't know about its existence. If Dawn hadn't ran across a mention of it in a cataloging of the Council's crystal library, it may have remained lost for another decade. Why the Council had invested in property in South Dakota was still a mystery, though.

Buffy had taken a small group to check the place out. None of the others had mentioned the mirror, but Buffy had looked pale when she'd come back. Sadder than Dawn could remember her looking in a long time. Only it wasn't the "I just watched a puppy die" kind of sorrow, but something more resounding and less final, an expression Dawn had seen on Buffy's face after she'd been raised from the dead.

Dawn wondered, even then, if the mirror was the one she'd read about… The Council called it a Quantum Mirror, but earlier references referred to it as the Demon's Window. There weren't any specifics on the object, as if no one had ever quite figured out what it was for. Only one thing was certain about it. Looking into it didn't show you a reflection of yourself, or of anything in this world.

Dawn had a hunch the mirror was in the lockup. She'd known she was right the moment she'd broached the question.

"Dawnie, no good will come from looking through it," Buffy had said, her only confirmation. Her green eyes were distant. "Don't do it."

For a long time, Dawn had listened to that advice. But Buffy wasn't here anymore. Buffy was gone to them, gone to the world. Probably dead, certainly lost. And Dawn was tired of holding on to the unspoken promise.

Dawn took a breath, reached out, her fingers grazing the cloth. She grabbed hold of it, but paused. Would this really help anything? What was the chance that maybe, just maybe, her sister was beyond the mirror? Unlikely. But she had to try.

Dawn gave it a solid yank and the sheet slid to the floor.

Staring into the mirror was like looking into a doorway, only the door wasn't sitting in a wall and the room beyond didn't exist. Where ever the mirror led to, it was dusty, and covered in boxes, supplies, the corner of a staircase just above. Was that a rifle? Papers were taped along the wall, shoved into files strewn across a narrow table at her opposite. But Dawn couldn't see all of it. It looked as if something was covering half of the mirror, and a second later Dawn realized she was right. The mirror on the other side had a sheet hanging off it as well, only it had slipped to one side.

This didn't look like any version of heaven or hell she'd ever heard of. She stayed for a few hours, but the scene remained the same. She covered the mirror when she left.

The second time she looked, she saw a man.

It had been a few months since her first visit, but business had taken her to Sioux Falls again, and she'd been unable to resist the temptation.

It took a few minutes, but the man finally saw her back. Dawn really hoped he wasn't going to have a heart attack. He looked kind of old and scruffy, the baseball cap on his head almost hiding his eyes from her, and he jumped like he'd been shot when he turned and saw the uncovered mirror.

When he calmed down, he rolled his eyes and said something aloud. Dawn wasn't a very good lip-reader, but she doubted the words were particularly nice. He raised a hand, as it to stop her from coming any closer, and disappeared from view. A moment later, he reappeared with a notebook and a marker and scribbled something onto the paper.

When he showed it to her, the words were backwards. Dawn's brow scrunched up as she interpreted the mirrored letters: "Don't touch the blame mirror, you idgit."

Dawn snorted and dug through the bag at her side, pulling out a yellow ledger. Before she could get a sentence written, though, he'd already flipped the page of his own notebook and scratched out something new.

"Where the hell is that Buffy girl?"

Dawn felt herself go cold. She wrote her reply and flipped the ledger to face him: "I don't know. Is she with you?"

She saw the aggravation fall from his face, replaced by something close to pity. Dawn knew without reading the reply that the answer was no.

It took a while, and the reading gave her a bigger headache than translating pictographs, but Dawn came to understand why her sister had told her not to look into the mirror.

The man's name was Bobby Singer, and he told her a bit about his last conversation with Buffy. They'd discussed their professions, that is to say, killing the big bad uglies who plagued the world. They'd talked about the mirror, how Bobby had thought for years that he was storing the legendary Light Eater mirror in the crawlspace of his basement only to find that its so called "vast darkness" was just a drape. Lastly, Buffy had offered her help.

Because that's what Buffy did when she saw people who needed it, and, from what Dawn knew, Bobby Singer was a man with a lot of enemies of the nonhuman variety. Oh, and his world was facing an Apocalypse.

This was the point in the conversation where Dawn began to understand why her sister had looked so sad. Bobby had said no to Buffy's offer.

Dawn's world, it was plagued with evil, sure, but that's what Slayers were for, to fight against the demons, the monsters, the darkness. To bring the balance. Bobby's world didn't have Slayers, just people who picked up the slack, tried to save as many as they could. Even though Dawn hadn't really thought about other dimensions quite as much since her time with Glory, she knew her sister had. Knew Buffy had known there were plenty of Hell dimensions out there, as well as strange, doomed alternate worlds.

But Buffy, at her core, was an optimist, or she'd never have survived high school, and Dawn knew that hearing about another place filled with just as much bad as this one must have rattled her. The grass was always greener on the other side, until it wasn't, and Buffy had taken that truth hard.

Dawn told Bobby bye for the day, made a date for the next night, and promised she'd look through her texts and see if she had anything that might help him out. The old hunter, still a little suspicious of anyone in his mirror, had tried to resist her aid, but Dawn had pouted and argued until he'd folded.

Buffy had told her not to look at the mirror. Of course, she'd had to have known her little sister wouldn't listen. When Dawn found her, and she would find her, she'd have to thank Buffy for the order.