Notes: So, uh. Hey, Supernatural fans. It's been a while. (Fans who were hoping for something else; don't worry. I actually wrote most of this a while ago and just polished it up before posting it. Everything else is still on track.) In case anyone hasn't noticed yet, I'm pretty into this concept, so here it is in yet another form.

Set in season 6, after 6.13, Unforgiven. Enjoy, and let me know what you think!

Warnings: language, alcohol, gore, violence. Basically if the show were R-rated.

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Dean was glad to have Sam back. Real Sam, who cared and pouted and beat himself up over stupid crap. In fact, 'glad' didn't even begin to cover it. Losing Sam (again) had felt like dying (again). Being with a hollowed-out shell that looked like him had almost been worse. Despite all the other crap they had to deal with, he was grateful beyond words to have his little brother alive and re-souled and more or less whole, however temporary that wholeness might prove to be. He really, really was.

But seriously, if the kid didn't stop ragging on him like an overprotective mother he was going to duct tape his damn mouth shut.

". . . cannot believe you would be so reckless. Actually, never mind, I can, because it's you. Dean "shoot first and ask questions later" Winchester. We didn't even know what sort of stuff she was into. We still don't. Anything could have happened, Dean. Anything."

"Yeah, well, it didn't," Dean snapped. "She's dead, the curse – or whatever," he amended when Sam made a noise in the back of his throat, "is broken, we're both fine – let's just call it a job well done."

"Yeah, sure. Just next time maybe give me a little warning before you blow up a freaking altar, okay? I almost got impaled by a cat's spine."

"Hey man, I didn't know the thing was going to explode," Dean defended himself lightly, glancing at his brother out of the corner of his eye. It had been a couple weeks since the seizure, but he was still keeping a close watch for signs of a repeat performance.

"Whatever," Sam said with a roll of his eyes, but a moment later he quirked his lips upward in a silent message. 'I know you're worrying, and you don't have to. I'm okay.'

It would have been more reassuring if Sam's definition of 'okay' hadn't included, among other things, experiencing head-splitting death visions, being jacked up on demon blood, and having no soul. Still, his wordless reassurance seemed to be proving genuine enough as the returned to the motel and set about getting cleaned up. Sam used his long legs to slip into the bathroom before Dean even had the door closed behind them, and Dean grumbled a half-hearted complaint as he set his weapons aside and began to strip off his grimy outer layers.

When he was down to his T-shirt and jeans he reached into his bag and frowned.

"Sam, have you been messing with my stuff?"

"You're the one with boundary issues, remember?" Sam called back from the bathroom.

Dean's frown deepened. He had been sure he had a half-empty bottle of Jack buried beneath his clothes. He wasn't far enough gone to have drunk it without remembering; not since he got Sam back. Come to think of it, he was sure he had tossed his bag down on the other side of the bed.

"Dude, seriously!"

"Seriously," Sam responded, cracking the door open to poke his head out, revealing a sliver of naked torso and denim-clad legs. "I didn't touch your stuff." He pushed the door open further. "Why, did you lose something? When did you –"

Dean wasn't sure what alerted him. Maybe it was a whiff of sulfur, or a ripple in the air, or the sound of movement. Maybe it was some sixth-sense memory, ingrained in him from the first searing pain of teeth on flesh. All he knew was that there was suddenly a hellhound in the corner of the room, and it was looking at Sam.

"Sam!"

The desperate cry was ripped from his throat, but it was too late, they were both unarmed and Sam didn't even have a fucking shirt and Dean was leaping for his gun but he could hear the hellhound surging forward and Sam was falling and Sam was down and Sam was –

Sam was laughing.

It was a real laugh, too, not an I've-completely-snapped-and-I'm-going-to-laugh-while-I-get-torn-to-shreds laugh. Just a normal Sammy laugh, a little breathless and disbelieving but not crazy.

"It's okay, Dean," said Sam, grinning at him from where he was still sitting, shirtless on the bathroom floor. His hands moved in the seemingly empty air in front of him, as if . . . son of a bitch, he was actually scratching the damn thing's ears. "He's just –" He sputtered and turned his head away, still smiling. "He's just saying hello."

"Saying hello," Dean repeated flatly, lowering his weapon. "A hellhound. Is just saying hello."

Sam shrugged unhelpfully, still fondling the thing, which was apparently trying to lick his face.

"Maybe he's just an invisible dog," he suggested.

"Oh, it's a hellhound."

Dean spun towards the new (weirdly familiar) voice, bringing up his gun while Sam scrambled to his feet, and found himself face-to-face with . . . himself. His own eyes glared at him over the barrel of his own gun, and the long-discarded amulet gleamed on top of a T-shirt identical to the one he was wearing.

The shifter, or whatever, must have managed to get the door open while Dean was distracted. At its shoulder was something which looked a hell of a lot like Sam, though this version was fully-clothed – it was also unarmed, and seemed alarmingly okay with that as it peered at them with a really, really good imitation of Sam's calculating look.

"What the hell are you?" Dean demanded, in unison with not-him.

They both stopped, glaring at each other. Behind Dean, the hellhound whined. Not-Sam whistled softly, and Dean tensed as he felt the beast brush against his leg on its way to its master. The thing came all the way up to his hip.

"What the hell's wrong with your dog, Sam?" Not-Dean questioned, never shifting his gaze. "Why aren't these two shredded?"

Dean risked a glance over his shoulder at Sam, who looked just as confused as he felt. Dean could almost hear his brain working, alternating between judging the distance to the nearest weapon and trying to figure out what the hell was going on.

"I think it's because they're not intruders," Not-Sam said. His hand was moving at his side, absently carding through invisible fur.

"Of course we're not fucking intruders," Dean growled.

"You sure look like intruders from where I'm standing," Not-Dean snarled back. Not-Sam sighed.

"Look, can we just put the guns down for half a second?"

"You know something I don't?" Not-Dean asked sharply. His aim didn't waver, and neither did Dean's.

"It's more of a guess, really," said Not-Sam, and damn, whatever these things were they were good. The only other Not-Sam which had been able to mimic him this well had been Meg, and she had had access to all his memories and brain patterns or whatever. "That witch we just killed – she was messing with timelines and stuff, right? Switching people with versions of themselves who had died when here they lived, or lived when here they died."

Sam sucked in a breath as if in sudden realization. Not-Dean shot him a cold look which made Dean want to rip his doppelganger in half.

"Yeah. Your point?"

Not-Sam opened his mouth, but it was the real Sam who answered.

"They're us. Or . . . we're you. From an alternate timeline."

Dean and his double stared at each other for a long moment, and then, slowly, the other him lowered his gun.

"Huh."

"Dean." Sam had moved closer to him, and Dean could feel the heat radiating off his bare chest. "Look at them. They're not shifters; they can't be demons. They're us."

Dean looked. The other Sam, plaid shirt over solid muscle, hair tucked behind his ears, fascination visible in twitching eyebrows and bright eyes. The other him, ivory-handled Colt at his side, tension in his stance, still glaring at Dean with suspicion and distaste. Sam's hand on a hellhound's back. The amulet glinting on Dean's chest.

He lowered his gun.

"What. The. Fuck."

Ten minutes later, Dean was really beginning to regret shooting that altar.

They were intruders, it turned out. The clean shirt Sam pulled from his duffel was one which had been shredded on a hunt months ago. The motel room – the damn universe they were in belonged to Other Sam and Other Dean, which at least explained the missing whiskey. It was a shame, too, because Dean could really use a drink right about now. Other Dean seemed to share the sentiment, and he dropped into a chair with a frustrated noise.

"Think it's time we phone a friend, Sammy," he declared. "And don't give me that 'he has bigger fish to fry' crap," he added before Other Sam could even open his mouth. "This is a freaking Great White and you know it."

Other Sam gave a long-suffering sigh and closed his eyes, while normal Sam glanced between them with his brow furrowed.

"Who are you –?" he began, but Other Sam cut him off.

"Hey, Cas, we've got a bit of a situation down here. We'd appreciate it if you could come take a look."

There was a rustle of wings which made Dean jump, and a very familiar figure appeared in the center of the room. Blue eyes flickered over the scene, from barefoot Sam and half-stripped Dean on the two beds, to Other Dean seated at the rickety table, and finally came to rest on Other Sam, standing by the door and looking slightly sheepish.

"Oh," said Cas – or Other Cas, Dean guessed, because his gravelly voice and impassive expression may have been the same as ever but his Cas didn't appear in a room full of Winchesters and look to Sam.

The hellhound growled.

"Shut it, Cujo!" Dean snapped, trying to let anger drown out the bolt of terror which shot through him.

"Don't bother," Other Dean advised him, with a glare in the invisible dog's general direction. "It only listens to Sam."

"He only listens to Latin," Other Sam corrected, in tones of one who had had this conversation before. "Just because you can't be bothered – never mind. Cas. Thoughts?"

"This is certainly . . . unusual. It appears that versions of you and Dean have been transported here from an alternate timeline."

"Yeah, we got that much, thanks," said Dean impatiently. "Alternate how?"

Cas – Other Cas, Other Cas – turned his head to regard him. There was a distance there which hadn't existed with the proper Cas in ages, a distance which Dean hadn't even noticed disappearing until it was back, and he rose from the bed without making a conscious decision to do so. It did nothing to lessen the feeling that he was being looked down upon.

"Explaining that would require a detailed analysis of advanced physics, causality, and the nature of Time," Cas stated, and if Dean hadn't known him (or some him, or whatever) he might have missed the edge of condescension in his tone.

"Fine," Dean said, an edge of entirely different kind in his own voice. "Let's start simple. Why the hell does Sam have a pet hellhound? How the fuck does that even happen?"

"Yeah," Sam agreed, rising as well. "Let's start there."

Other Cas tilted his head to the side in puzzlement. Behind him, Other Dean and Other Sam exchanged dark looks, and Dean felt dread trickle down his spine even before Other Cas spoke.

"I would have thought that was obvious. In this reality, Sam is the King of Hell."