Disclaimer/Spoilers: Everything up to and including season 11. Also don't own Supernatural. Just playing in a great little sandbox created by Kripke and company.

A/N: Entropy is the 3rd and final part of the Providence verse. This story may not make any sense at all, unless you read Providence and Causality first. So if you haven't already, go "MMMbop" your way over there. For those of you coming here from Causality, I hope you enjoy the story and don't forget to tip the lost souls on the way out.

Entropy – Lack of order or predictability; gradual decline into disorder

Until The End

Why give up, why give in?

It's not enough, it never is.

So I will go on until the end.

We've become desolate.

It's not enough, it never is.

But I will go on until the end.

Sam squeezed his eyes shut as the world shifted from underneath him once more. His stomach churned but it wasn't due to the sudden angel teleportation. It was because of the scene they were leaving behind. It was because they were leaving Dean behind.

They stood on that hillside for what felt like hours, helpless and awed as they watched the column of otherworldly light funnel up the night sky. Then Sam had broken from his stupor and surged toward the downhill slope, toward the convent, his heart pounding, his head swimming. Dean was still in there. His older brother was in danger, again, and they were just standing there. But Cas had stepped into his path and placed a firm hand against Sam's chest, told him that the column of light, the high-pitched noise they'd heard – that was Lucifer breaking free from his cage.

They'd failed.

Well, Lucifer could be twice damned; Sam was going after his brother. He wasn't about to allow Dean to be some sacrificial lamb left to slaughter. He got an arm up between them and tried to push past Cas, but the angel had simply lifted his fingers and touched Sam's forehead. Everything went swiftly black.

Sam wasn't sure how much timed passed before he came to, but they were still on the same damned hill. The only noticeable difference to the night was that the blinding column of light that had rent the sky was gone. With fury heating his chest, he pushed himself to his feet on trembling arms. "What the hell, Cas!" he demanded, taking a step toward the angel. He knew he was no physical threat to Cas, but that didn't quell his rising anger or keep his hands from forming tight fists at his sides.

When Castiel turned toward him, there was something floating just below the surface of his steady gaze, but Sam struggled to put a name to it. "Staying there any longer would have served no purpose but our deaths." The angel paused, then quietly added, "or worse."

"So, we just leave Dean there alone, again, to bite the bullet!" Sam dragged his hands roughly through his hair. What he was feeling about these recent events went beyond frustrated. They should have gone in for Dean when they had the chance. Cas should have gone in for Dean.

They stood on the hill for another few quiet moments before Sam's anger deflated and his shoulders slumped, and he broke the silence. "We have to go back to . . . " He couldn't bring himself to finish, because it didn't matter. Because he knew Dean wouldn't be there. Either his brother was once more in demonic hands, or he was dead. He couldn't bear to say it out loud, but Sam couldn't imagine any scenario where Lucifer, the devil, let his brother walk free and unarmed out of that building. It was the devil they were talking about.

Cas nodded solemnly and gripped both Sam and Bobby's shoulders. The world shifted in an odd, weightless flash that Sam swore he would never grow used to, and then they were inside the broken hallways of the chilled, dim convent. Sam immediately took off down a hallway, even though he had no idea whether he was going in the right direction.

Rooms lined the hallway on either side. Heart pounding anxiously, Sam paused at each doorway only long enough to confirm they were empty.

"Sam." Bobby's quiet voice echoed through the hallway.

He stopped short, looked over his shoulder to see Bobby gestured toward a room. With somewhat wooden legs, Sam followed the older hunter inside. There was some sort of altar on the far side of the room, and . . .

And nothing. Sam rolled his bottom lip against his teeth, dragged a hand over his mouth. There was nothing here. No other sign that Dean or anyone else had been in the room. Even the thick dust that coated every surface looked as though it hadn't been disturbed in years. The only hint someone had been there was the altar and the shiny brass bowl sitting on top, looking out of place in the room.

"Now what?" Bobby asked.

Sam took a deep breath in an attempt to still his racing mind. Now what? Lucifer was free. Dean was . . . God only knew where, assuming even he did. They were looking at a full-blown apocalypse, right in the face. "Head back to the bunker," he finally said, hollowly. His words hung heavily in the air. There was nothing left for them here. "Regroup."

Footsteps crunched behind Sam, and then the world around him shifted for what he hoped was the final time that night. He blinked, momentarily blinded by the harsh lights of the bunker.

He took a few heavy steps into the bunker's library, only to stop short at the sight of someone waiting for them at the far end of the room. The man's head was down, his forehead resting on clenched fists, elbows propped on the table. Relief flooded through Sam, and he felt dizzy as he closed the space between he and his brother.

"Dean?" Sam nearly dropped to his knees at his brother's side, had to place a palm on the tabletop to remain standing. His head buzzed with adrenaline, and at the same time, an immeasurable weight was lifted from his shoulders. Lucifer breaking out of the cage was a serious blow to the game plan, but his brother was here, was safe, and that was all that mattered. Whatever problems lie ahead, they'd face them together.

It was a few moments before Dean straightened in the chair and dropped his hands to the table. When he lifted his eyes, his gaze held the tired look of a man who had fought the good fight, and found that he just wasn't good enough.

Sam was physically rocked a step back by the look, and his heart sank like a heavy rock into his stomach. Before he could question his brother, Bobby cut him off.

"How . . ." the older hunter asked, then flapped a hand uselessly.

The room was silent for a long, tense moment before Cas answered, "God."

"What?" Sam's neck nearly cracked from the force with which he turned to the angel. He'd felt for a while now that he was barely keeping up with the others, and the mention of God made all of this seem well above his pay grade, and beyond his puny human abilities. "God?"

Dean's throat worked around a rough swallow, and his chin dipped. He rubbed at the back of his neck. "Yeah," he said, voice choked and hoarse. "He's done it before."

"Done what?" Sam asked, finally falling into the chair next to his brother.

"Saved me. Us."

There were libraries of information he hadn't shared with Sam; that much was clear. He'd had a feeling, but he knew now for sure. Whatever they had been through, whatever he or Dean had done . . . he'd hardly scratched the surface of understanding. He was flirting with the frayed edges of his exhaustion, his anger, but Dean looked like he was hardly holding himself together, and now was not the time for an indignant explosion. Instead, he turned to Bobby and Castiel. "What the hell do we do now?"

Bobby pressed his lips into a tight line. "Now we figure out what to do next."

Dean shook his head. "Bobby, I don't think—" The words caught in his throat, voice thick, like a man who had reached the end of his rope and didn't know what was left to hold onto.

"I said, what do we do next, Dean?" Bobby's voice firm, but was also laced with more understanding, more empathy, than Sam had thought possible of the old hunter.

Dean pressed his fist against his mouth, taking a moment to collect himself before clearing his throat. "Right. Okay, right." He nodded letting his hand drop to the table with a heavy thud.

Bobby nodded once. "We have a full-blown apocalypse on our hands. We need to know what the devil's first move is gonna be and figure out how to stop it."

"The horsemen," Dean said. "He'll raise the four horsemen, starting with War."

Bobby nodded, gaze moving between Dean and Castiel. "You remember when and where?"