A/N: Hello, lovely readers! :) This fic is the prequel to one of my other fics, Family Matters, but being a prequel, it can stand alone so if you haven't read that one, it's totally fine! This IS an AU, beginning right after Sam jumped into the Cage at the end of S5.

Which means, of course, that we ARE going to see some Lucifer, so I'm putting some warnings in because he's creepy and evil and likes to torture them. (I mean, what fun would this be without some whump?)

I don't own the SPN characters. Thanks to Aini NuFire for being brave enough to beta this for me! :D

Chapter 1 - For You, I'd Brave the Deepest Hell

"I'm going after Sam, Dean. If it's in my power, I'll bring him back."

Castiel flew through the thick quagmire of Hell, the noxious fumes of the fiery bog threatening to overpower his senses. Despite the grace shielding his wings, his angelic essence offering protection from the evil surrounding him, Castiel nearly faltered. He'd thought going in only far enough to rescue Dean had been bad; this was much, much worse.

But he had promised, and he had to keep going. The angel knew how lucky he was to have made it this far so easily. Hell had been thrown into chaos with Lucifer's return to the Cage. The only reason the demons hadn't found him yet was because they were already in such an uproar that they probably wouldn't have noticed God himself descending through their ranks.

Even still, it would be a miracle to make it all the way to the Cage and back unchallenged.

"I'm coming, Sam," Castiel muttered out loud, eyes narrowing as he navigated around a plume of reddish-yellow heat erupting from the soggy ground like a molten cloud. The farther down the circles of Hell he flew, the fewer demons he had to avoid. It had been some time since he'd seen the last one, and the angel suspected he must surely be getting close.

The sooner he got there, the better. It had already been a full day, up on Earth, since the battle in Stull Cemetery. A full day since Sam had willingly hurled himself into the abyss, destroying himself in order to save the world. Though Castiel had known that this had been the plan, actually witnessing the event had made a lasting impression on him that changed everything.

How wrong the angels had been about Sam Winchester. Any quiet doubts that Castiel could have possibly held onto about the young man had been soundly eliminated.

"He- he actually did it?" he'd asked an utterly broken Dean. The hunter had only nodded, not looking up from his ninth or tenth drink. Castiel wasn't sure which was worse: the berserk, mindless, raging Dean, or this broken, silent, ruined one. So far, the hunter had manifested both in the wake of his brother's death.

Sam Winchester, Castiel thought with a shake of his head as he flew faster through the depths. Not the boy with the demon blood; rather, the boy who loved the broken, wretched world enough to save them all. The boy who'd been offered unlimited power and immortality, but who'd turned it down in favor of his brother, his friends, and his people—most of whom would never even know his name, let alone what he had done for them.

It was a kind of selflessness and bravery that shook Castiel, simply because the angels had never believed that mere humans were capable of it.

And Dean… Dean, who had spent his life chasing nightmares, never getting to enjoy the same life of safety that he fought to give others. Dean Winchester, the righteous man who had resisted Hell for forty years. The man who gave, and gave, and gave, but never took a thing. The man who had stood nose to nose with the Devil, knowing that he would find nothing but death, just so that his brother wouldn't die alone.

The Winchesters only reaffirmed Castiel's steadfast belief that these people were worth fighting for… that they were not, in fact, a failed experiment.

And Castiel could not – would not – allow Sam to suffer for eternity at Lucifer's hands as payment for the single most amazing act of sacrifice of the age.

The air was starting to get thicker now, smoke and ash combining in festering waves of searing heat. Castiel narrowed his eyes, trying to pierce the growing darkness. Surely he was nearly there. The angel had been flying for what felt like days, and that made him fear for Sam. Time worked differently here; it would be only a day and a half in Earth time, but down here, the human had been trapped with Lucifer for six months already.

In spite of his promise to Dean, Castiel was deeply and terribly afraid that he was already too late.

Now he was nearing the heart of Hell itself, lower than the lowest circle. Quite different from the fiery marshes, the Pit was nothing but a vast space of swirling black so thick that it burned Castiel's eyes and clogged his mind. It was vapor and evil manifested, and there was no need to fly through it… it dragged him down on its own, and very soon the angel would be at the epicenter of everything dark and terrible in Creation.

The Cage, where Sam had been doomed to spend eternity.

"He's my baby brother, Cas. I was supposed to save him. It wasn't supposed to happen like this. You HEAR me?! It WASN'T SUPPOSED TO BE LIKE THIS!"

"No, it wasn't. He doesn't deserve this. …..Dean, I- I think I can reach him."

"…What?"

He'd been returned with stronger powers than ever, after all. What reason could there possibly be for that, if not to give him the strength to reach the Cage in the first place? As a lower angel, Castiel doubted he could have made it this far. But as a seraph…

Finally, Castiel slowed to a halt as he reached his target at long last, staring up at the pulsating, crackling dome with dread in his heart. The ethereal streaks of turbulent, energy that formed the Cage emanated a brilliant, white-hot glow, offering some illumination in the otherwise pitch-black of the bowels of Creation. From the outside, Castiel could have walked a circle around the entire dome in less than a minute, but he knew it would be another matter entirely once he stepped through. The Cage wasn't a physical prison so much as the boundaries to an empty world for Lucifer alone. It might have been as small as a single room or as large as all of Heaven; in the end, it didn't matter.

Again, Castiel faltered, feeling millennia of evil, rage, and insanity seeping out of that Cage to poison Hell with more noxious fumes. Even facing down Michael or Raphael had not been this terrifying. If Lucifer caught him, it was highly unlikely that he would be merciful enough to give him another quick death.

Squaring his shoulders, Castiel reached a tentative hand towards the dome. He could feel the power it generated, the barrier which held the mighty Lucifer bound. Getting in would be nothing; he merely had to step through.

Getting out was something he didn't want to think about just yet, for the Cage required a toll that the angel had neglected to mention to Dean.

He could not hesitate any longer. Sam had been alone with Lucifer and Michael for too long already, the perfect target for their wrath besides each other. With narrowed eyes and quaking heart, Castiel shoved his way through the dome, even knowing that this was the point of no return.

SPN SPN SPN

The interior of the Cage was nothing like what he expected.

The darkness seemed appropriate, his surroundings lit by nothing but the continuous flashes overhead from the energy forming the domed ceiling. Castiel kept waiting to hear thunder to accompany the eternal lightning, but none ever came. In the strobing light, the angel could see trees, and that confused him. Surely nothing could be growing down here. They were everywhere: trees, bushes, too dark to get a good look at, but he was most certainly surrounded by plant life.

On closer inspection, Castiel realized that the trees didn't simply appear dark due to the intermittent lighting; they were actually black, and the leaves were shriveled and cracked. The angel backed away with repulsion from one plant that had at first appeared to be flowering with red roses… in reality, the flowers were dripping with blood, leaving ominous pools on the ground beneath them.

Even the Cage floor was crawling with shadows, rather than grass. They couldn't have all been cast from the trees and bushes, because even in between the flashing lightning from the dome high overhead, Castiel saw the blackness moving beneath his feet, tangible to the point of solidity.

Castiel crept through the Cage as silently as possible, tense and ready for an attack. The angel blade in his hand was really more for his own comfort than for any practical use. If he ran into Lucifer, it would be worthless anyway, but the soldier felt better with his weapon drawn. But how was he going to find Sam?

The powerful presence of evil in this place was so oppressive that it pricked the corners of Castiel's eyes and even the staunch warrior felt an overwhelming desire to flee.

Of course, it was far too late for that, and Castiel forced his feet onward, blade tight in a white-knuckled grip. Sam. He had to focus on Sam.

He'd have to go to the center of the Cage, the angel decided. Lucifer wouldn't want Sam anywhere close to the border of his domain. The barrier was never designed to trap a human, so Sam could technically walk right out. The problem was, he had jumped into the Pit, body and soul, which meant his physical shell would still have been stuck wandering the basement of Hell with no way out.

Though, that problem was academic anyway, as Lucifer would certainly be keeping a firm hold of Sam to prevent him escaping.

Castiel continued on his trek, swallowing back his revulsion of the shadows that curled towards him as he stepped through them, navigating around the trees. Physical tendrils of the strange darkness snagged at his feet, starting to curl up his legs if he held still for too long. It bothered him that he'd heard nothing so far. How large was the Cage interior? Did it truly extend for eternity? He was alone, ghosting through a sea of shadow.

"Sam," Castiel whispered, feeling desperation start to tug. The angel wanted only to get out as fast as possible, back to the light. He could almost feel his grace shriveling back from this terrible nightmare. "Please, give me some idea of where you are…"

How far had he come from the border of the Cage? Castiel risked a look over his shoulder, and wished that he hadn't. He was utterly surrounded by the black trees and flowers of blood, and the chilling flashes of light. The angel was certain he'd walked far enough that he should have made it straight through to the far wall by now, which meant the inside was certainly larger than the outside.

Finding their way out again would be as hard as finding Sam was turning out to be.

Wait. The angel stiffened, freezing in place as he felt a slight shift in the air around him. The shadows were pulling away slightly, less thick in this direction. He thought he could see a clearing in the trees ahead, so Castiel turned his feet in that direction, creeping along as silently as possible.

If he was very lucky, he'd find Sam unguarded, and perhaps Lucifer wouldn't even know he was there until they had escaped.

A soft cry tore from the angel's throat as he finally caught a glimpse of a shape farther ahead through the branches. Though Sam was still warded against his senses, he was the only source of light or goodness in the entire Cage, and Castiel was drawn towards him like a moth to flame.

"Sam!" he called hoarsely, rushing forward into a hollow as he saw – unbelievably – that his human friend was unguarded. Perhaps Lucifer was elsewhere, fighting with Michael. If so, this window of opportunity might not last long.

Castiel broke through the tree line and flew to Sam's side, then came to a dead stop with horror in his eyes.

Sam Winchester was curled on his side on the dark floor of the massive prison, unmoving. His clothes were in tatters, barely clinging to his wasted form. The poor human was shivering uncontrollably, the only sign that he was alive at all, and while the blood and bruises were bad enough, it was his eyes that nearly drove Castiel to his knees.

There was nothing. Nothing at all. Not even fear, not even despair. Those were the eyes of a dead man, stripped of all humanity, all self, all sanity. Castiel's stomach turned, and his heart quaked; was he too late?

Sam shifted then, and Castiel gasped with surprise and hope. Had the human realized he was there? "Sam, it's me. It's Castiel. I've come to get you out."

Though, he wasn't sure yet how he would do so. The angel frowned, registering now that the shadows weren't truly lessened here, but rather they had condensed and tightened into solid coils that wrapped around Sam's wrists, binding them behind him. When Castiel tentatively reached out to touch the shadow restraints, they felt smooth and cold, like metal made purely of darkness.

"Hold on, Sam," he urged quietly, not certain if the hunter could hear him or not.

"You're… off… your game…"

Castiel straightened back up, eyes darting back to his friend. The hunter wasn't looking at him, staring listlessly ahead. "Sam?"

A shudder ripped through the human, and he tried to shrink away from Castiel. The angel's heart faltered in his chest as he felt Sam cringe at his touch. His friend's words were ragged and dry, like he had used up all his voice already… probably screaming, by the looks of things.

"You were… just… Cas… last time. Right after… Dean. I-It's… Bobby's turn… Remember?"

Castiel knew he should have expected this – had expected this, even – but he was momentarily overcome as the implication settled in. Lucifer was using the forms of all the people Sam cared about to torture him, which could only amplify the pain he was obviously receiving. The angel felt his throat constricting, and he clawed his way through the despair looming over him.

"It's really me, Sam," he assured his friend gruffly. "It's Castiel. I'm not going to hurt you. I'm going to save you."

Quickly, he turned his attention back to freeing Sam. The shadows which wrapped the hunter's wrists were emanating from the rest of the surrounding tendrils that spread across the ground, effectively chaining Sam to the floor. With no other ideas, Castiel raised his blade, striking the shadow as hard as he could.

It was useless. The angel held back a cry as his arm was jarred painfully at the impact, but nothing could silence the resounding clang that seemed to echo off every shriveled tree, every dying leaf. Castiel's fear multiplied; he'd just informed Lucifer that he was there.

Cursing, the angel tried once more, determined, but once again the blade refused to make even a dent in what should have been mere vapor. How was this possible? What were the shadows even made of?

"There's no point," Sam whispered, hollow and faded. For a second, Castiel almost thought his friend was becoming aware of the escape attempt in progress, until he finished, "I know it's you, Lucifer. The real Cas… is dead. You… you used my hand… you made me kill him…"

Of course. Sam didn't know Castiel had been brought back. The angel sighed in frustration and fury at Lucifer, before stowing his blade back in his sleeve and simply gathering the hunter up in his arms. If he couldn't cut the strange bonds, he would use his restored power to pull Sam free. The human weighed nothing, cradled against him without attempting to help or escape his grasp. His bound hands hung behind him, as Castiel grabbed the solid darkness and flew backwards with every bit of strength he had in the hopes of at least severing the shadow connecting Sam to the ground.

Nothing.

"What is this?" Castiel demanded desperately, knowing with a foreboding certainty that he was almost out of time. "Sam, I will get you free, I just-"

The angel broke off, ice touching his heart as the bottom of his stomach dropped. The shadows… they were whispering.

They were saying his name.

"Castiel… is that YOU, Castiel?"

…Oh no.

The warrior looked down, inhaling with panic as he saw the tendrils of black fog he'd been standing in start to weave around his feet, sliding up his ankles. "No!" he gasped, jerking one leg free and then the other. "Sam-"

"Castiel… hello, brother."

In his arms, Sam frowned, the first bit of clarity returning to his haunted eyes, as he looked up at the angel. His cracked lips parted, then he hesitantly murmured, "Cas?"

It took everything the angel had to keep the cloud of panic from paralyzing him completely. "Yes, it's me," he whispered, pulling his legs free again from the insistent shadows. "Can you-"

He cut off with a cry as Sam was suddenly jerked away from him too ferociously for him to keep a grip on his friend. Sam was slammed onto the floor of the clearing, making him groan with pain. The coils around his wrists separated to yank his hands apart, fastening them to the ground by his head. From all around Castiel, the shadows were suddenly lashing up towards him, too fast to be fended off. They wrapped the angel's arms and legs before he could reach his blade, tightening in a crushing grip with his hands pinned to his sides.

He was trapped, bound in an instant.

"Castiel," the darkness whispered, Lucifer's voice surrounding them now. Castiel bit back a shout of alarm as he was hoisted off the ground completely, suspended by the living shadows that circled his feet, torso, and shoulders.

And then, Lucifer was standing before him, back in his original form. An insane smile lit the devil's face as he reached out and stroked the terrified angel's head.

"Oh, now… this is going to be fun."