The old stone warehouse was vast.

Once upon a time, decades before, it had been used for industry: its sloped slated roofs had overseen the hustle and bustle of many strong men, shouting, cursing and joking as they manoeuvred barrels, or perhaps steel girders, or possibly boxes of produce, all packed up and ready to be shipped.

But now it stood empty and in silence, leaving only the rats to make any sound at all. Their trails could be seen in the thick layers of dust, mostly fallen from the decaying and all-but-disintegrated upper storey that used to be small offices but now, having been reduced to their smallest atomic unit, instead covered any and all surface: the floor; forgotten and abandoned crates; used takeout boxes; the occasional used condom from the daring or the desperate; an old broom, useless now; a never emptied trashcan stinking and rotting from the inside out, the white powdery dust covered it all as if making its own internal landscape.

"Home from home!" Dean joked as he shone his flashlight around.

"Which way do you think it went?" Sam, serious as always, was already trying to pick out any tracks in the near gloom of the abandoned building: it didn't have many windows anyway, but what there were, were all boarded up. The last radiance of the full moon outside wasn't even coming close to filtering through.

"It can't have got far: we were right on its tail. There!" Dean used the beam of his torch to pick out the footprints: prints with long strides between them and the dust kicked back as if something had been running very fast and away from them.

As indeed it had been.

The light from the flashlight tracked the marks in the dust, following them as they suddenly veered to one side and led to another door at one edge of the building, "Okay." And Dean stopped and made sure the door they had entered by was properly secured. "He ain't going out that one!" as he pulled the bolt across. "Let's get this sucker."

He led the way across the dusty moon landscape, leaving rippled impressions of his own first footprints as they began to also move carefully towards the door. The older brother leant forward and carefully opened it with his left hand, the right now being full with his gun.

There was a set of steep metal steps leading down into all but total darkness. The two Hunters exchanged glances, both on full alert, and with practised ease began to make their way down: Sam covering Dean as he went first, wary of hands, or claws, reaching through the rungs to snatch at ankles, shining his torch and gun together in one single sweep at a time.

Nothing.

Soon they were both at the base of the steps, and could see they were in a large lower area. Almost a cellar, a large cellar, used either for supplies of 'goods in' or as storage for the final products of whatever business at the time, or both, as there were deep scratches on the floor where things heavy had been pulled around on pallets often enough to make their own ruts. At the other end, and up on a large dais, they could make out the cracks of light around what was a large lifting-style warehouse door that opened up the whole area to the outside, and the rusty old harness system that had been used to manually move goods up there before the onset of forklift trucks simplified the process even further. "Any sign of its tracks?"

"Nope." Dean's sharp eyes were already scouring the area, looking for any sign of where the were-creature might be hiding. He swung the light above them without success. "Less dust down here. You go that way: I'll take this."

"Careful."

"Yes mom!" And they were moving forward into the darkened open space, alert for any movement, any noise.

Nothing.

Between them they scouted the entire area, trying to also keep each other within view as well. The night started to recede as they searched and soon the traffic noise outside of early morning commuters began to filter through.

They realised there were other sets of steps down to this level, and a large old-fashioned, rope-all-but-frayed-through elevating device to help move heavy items between the two floors. Modern-day Health and Safety regulators would have had a fit at all of it, but it also meant that there were plenty of ways out. Then Dean sighed further as he noticed the small outer door up beside the large lifting warehouse door on the dais and hurried up the few steps at the side of the platform to get there and try the handle.

Just as the first door had originally been, it was unlocked and opened easily out onto the other side where he found himself overlooking an old paved level courtyard that led through old gates to the electric-lighted street beyond. At some point lorries, or carts in earlier times, would have been backed up to the exterior of the warehouse, the dais being the perfect height at this side's street level, the other side from the general worker's entrance, to allow for easy loading of heavy goods. But no longer. The main door wouldn't have been used for years. And neither had the cellar.

"Shit! Looks like he knew where he was going!"

"Any sign?" Sam called as he also began to cross towards the raised platform.

"Nah. If he came this way then he's long gone." Dean was putting his gun away, tucking it into the back of his denims as was his custom. Glancing up, he could still see the waning beauty of the full moon seemingly directly above the old building as it finally began to be overthrown and hidden by the double whammy of the increasing light of dawn and of Kansas City fully coming awake.

It seemed to wink a good-natured goodbye to him and despite himself, he smiled: he had always loved watching the night sky, although given the choice he always preferred to see it from the peace and solitude of the countryside rather than a brash and glaring city. Even though somehow, it seemed larger tonight than he had ever seen it before. Dean shook his head at himself, he was getting distracted: "Let's get back, grab something to eat, try again tonight."

"Okay." The younger man agreed and began to head back across the stone floor.

Dean closed the outer door and moved to follow but then something caught his attention. "What's that on the floor beside you, Sammy? I didn't notice it before."

"What?" He was looking down and shining the torch around his feet. "Where?"

"Well, there!" Dean jumped down off the platform and began to cross to where Sam was standing, staring at him. "That bright blue thing, it's glowing for fuck's sake: how can you be missing it?"

"Dean, there's nothing there!"

"It's small and glowing really bright light blue! What's wrong with you, Sam?" And he was there, right beside his younger brother and bending to pick something up from within only one step away of the other's large foot. "It's getting even brighter! Look!"

"I can't see it, Dean! Careful for God's sake: we don't know what it is…."

But the warning was given too late. Because all of a sudden Sam did see the pale but blinding blue glow. In fact it was all he could suddenly see.

For, as his brother's hand connected with whatever it was, the glow grew and expanded to become a dazzling, painfully blinding pale blue light. A light that became a blast of glowing blue-white energy that took Sam off his feet and threw him until he was connecting with the stone wall of the cellar.

And then there was nothing but blackness.

It seemed a long time before he could move again, groaning and blinking against the effects of the sudden intense brightness that had left dark spots instead of vision, calling for his brother as soon as he was able.

No answer.

It was a few minutes longer before the dark spots had cleared enough that he could even try and look around the cellar, still calling Dean's name.

Nothing.

It took him a long few minutes to locate his flashlight and realise that it was smashed beyond repair, leaving him almost useless in the gloom that seemed now to be even darker than it had before. Hastily he stumbled over to the dais and up the steps, fumbling on the wall beyond for the release that would allow him to open the large lifting door and allow the morning light to flood as far as it could reach into the cellar.

Then it took Sam a few more minutes of desperately searching with his eyes around the still too shadowy area to finally spot the bundle lying at the base of the wall opposite.

A bundle of clothes and living flesh that was his brother.

A bundle that wasn't moving.

"Dean? Dean!" And Sam was hurrying back down onto the main floor and staggering across to the motionless huddled figure half hidden in the gloom. He fell to his knees beside it and reached out with a panicked hand to feel for a pulse. Thank God, Dean was alive. Although his heart rate was racing beneath Sam's touch.

And at his touch, his brother finally stirred. He started to moan, and….whimper? He must be seriously hurt to make a noise like that. Quickly Sam checked him over, pulling him onto his side, touching and testing to find any blood; any signs of broken bones; and any increasing lumps or bruises that could indicate internal bleeding.

"Sam?" Dean was coming round and trying to move, beginning to sit up. Sam helped him despite himself, although he really wanted to make him lie still. He seemed to have been unconscious for a long time. They both had.

But then to Sam's surprise and discomfort, his brother was reaching for him suddenly: grasping for his arms and pulling himself closer between them to the younger man until his chest was pressed tightly against his body. Really tight against him.

"Um, Dean?" He felt like he should put his arms round the smaller man, but…this wasn't only his brother, this was Dean. And Dean did not do chick flick moments! Perhaps he had really banged his head hard?

"Sam, what was that?" Dean must have smashed his head hard, Sam could feel him physically shaking and trembling against him. Despite himself, he did move his arms to surround his brother's smaller body and try to calm him.

"I don't know, but I think we need to get you to a hospital."

"I'm fine: I just want to go home. Can we go home now, Sam? Please? I don't like it here."

Sam blinked and looked down at the man all but buried in his arms. And he realised something strange: Dean was no longer wearing his leather jacket, jeans and boots. Somehow he was wearing a dark green sweatshirt with a collared shirt beneath, dark slacks and some type of sneakers. How had he changed his clothes?

And at the same time, Dean was taking a deep breath in to try and reassure himself that he and Sam were safe. And then he stopped and inhaled again. And then he was pushing Sam almost over on his back, burying his nose into his brother's neck and really, really breathing in, as deeply as he could.

Then he was just as suddenly pushing Sam away and leaping backwards away from him with one incredibly swift, abnormal movement from a sitting position to land cat-like on his feet. "Where's your scent? It's gone: I can hardly smell you! And where's your suit?"

They stared at each other for a horrified moment as both came to the same unbelievable conclusion.

"You're not my Sam! Where's my Sam? What have you done with him?" And Dean was backing away across the room, tears glinting in his eyes, eyes that were wide with fear.

Sam hurried to get to his feet. This was impossible. This wasn't Dean. "Wait…."

But the other was already turning and running for the way they had come in. And he ran fast. Faster than Sam could almost follow with his eyes into the near darkness as he also broke into a run, desperate to try and stop his brother…thing that looked like his brother….from getting away from him.

He took the metal stairs three at a time but still only reached the top in time to see Dean, or whatever it was, struggling to undo the heavy metal door that they had originally entered the building through. "Wait!" Sam put on a sprint to try and stop the other from getting through that entrance and out into the street.

But he wasn't quite fast enough as Dean finally managed to pull back the heavy bolt and slipped through the doorway, pulling it shut behind him with a loud slam that caused Sam to lose precious time in trying to follow. He swore and swung the metal back, anxious not to lose sight of his brother as he emerged into what must now be rush hour in Kansas City: if he lost him amongst all the commuters, he would struggle to find him.

His heart plummeted as he saw the being that looked like his brother already at the entrance to the alleyway that they had followed the fleeing were-creature into. "Dean, wait!" It was a last ditch attempt to stop him from simply running into the crowd of pedestrians that were already making their way to their jobs for the day, but he knew he was already too late.

But to his relief, and his surprise, the other man faltered. He just stood at the edge of the alleyway at the multitude of milling faces, and seemed to freeze where he was. Then just as Sam had nearly reached him, Dean was backing away from the street, his footsteps unsteady and erratic.

Sam took his chance and simply crashed into his brother, taking him right off his feet and slamming him into the wall of the building beside them. Then before Dean could recover and swing at him, he was wrapping his longer limbs around the smaller man, using his weight advantage to tie him up in a cage of solid, strong living muscle and holding him down physically on the ground.

He braced for the counter attack that would surely come.

But there wasn't one. Instead his brother simply stared up at him and whimpered with fear. "There's too many people, but no scents! Where's all the scents? I can't….not the people! What is this place? Where's my Sam? I want to go home."

And then to Sam's consternation, he began to cry.