Cas had tied Dean to a chair in the middle of the iron Devil's Trap. Ropes wound around his wrists and ankles bound them to the arms and legs of the chair. The thick metal collar locked around Dean's neck was anchored to an iron ring embedded into the concrete floor. The overhead bulb cast his face in deep shadows, making him seem half-consumed by the blackness. Black eyes watched Sam from hollowed depths.

Sam walked over to the table braced against the side wall and opened the black case filled with eight syringes. From his inside pocket he pulled a ninth, this one twice the size of its plastic fellows. Metal braced the cylindrical compartment inside, as well as the hooped plunger. This was the syringe Castiel had used to draw the remnants of Gadreel's Grace from inside him.

Suddenly feeling uncomfortably hot, Sam shed his jacket and laid it carefully on the tabletop. Cas stepped up beside him.

"Are you ready for this?" he asked, his eyes never leaving the demon.

Sam nodded curtly. "Almost. There's one thing I gotta do first. Will you do me a favour?"

"Of course."

"Bless this."

He reached out beyond the pack of syringes and flipped a piece of dark cloth aside, revealing a beautiful dagger gleaming against the grey folds. The blade was almost a foot long and curved three times like a winding river of silver-white steel. Its point was perfectly straight and sharp, even though Sam doubted it had been sharpened since at least the time of the Men of Letters. Its red leather-bound hilt was woven through with thin strings of gold twisted into Celtic symbols that caught the light, making it glisten subtly as Sam picked it up. The pommel was embedded with a ruby engraved with one of the oldest symbols of protection: a five-pointed star bound in a circle wreathed in flame. The same symbol that was tattooed on Sam's chest.

Castiel's eyes widened as he gazed at the stunning weapon. "Where on Earth did you find this?" he gasped.

Sam's mouth quirked briefly. "In the Bunker's storage room. The Men of Letters had it tucked away in there for who knows how many years."

"The Anam blade." Cas breathed the name with reverence.

"Yep. And I need it blessed. The ground too. Would you mind?"

Still staring at the entrancing knife, Cas nodded. "Of course."

"Thanks. I'll be right back. Then we'll ... then we'll get started."

Casting a final glance at the demon, Sam walked out of the dungeon and headed for the chapel.

Nerves began to gnaw inside him. Anxiety and fear curled like a pair of poisonous snakes in his stomach and he placed a bracing hand to his abdomen, trying to steady the sudden nausea. This had to be done, he thought firmly, and being nervous about it was only gonna make it worse.

The snakes ignored him.

The Bunker's chapel was smaller than Sam's bedroom. There was no alter, though crucifixes hung by the dozens across the unpainted walls. Four short pews stood in perfect alignment, leaving only a small gap to their right to allow visitors to file into the small, hallowed room.

There was nothing in the chamber to suggest it was anything more than a place to store crucifixes – no stained glass windows illuminated from behind, no tabernacle, no fount of holy water. The only reason Sam – and, he presumed, the Men of Letters before him – called it 'the chapel' was because of its inexplicably warm and comforting atmosphere. It had the same welcoming feel to it that Sam had come to associate with hospital chapels: those that knew true, heartfelt and sincere prayers, usually born of love and beseeched on behalf of others. Perhaps, given their grim work, the Men of Letters had included this small anteroom as an oasis from the sorrow and helplessness their job engendered. Perhaps the architect had been religious.

Either way, Sam was relieved to sink into the third pew from the door, facing the largest and simplest-looking crucifix. Taking a deep breath and willing his stomach to unclench, Sam blessed himself.

For the second time in his life, Sam Winchester knelt in against hard, cold wood in a place of worship and wondered if he truly could be forgiven the unforgivable.

"I, uh ... I've done a lot of wrong this year," he began, keeping his voice low as though fearing being overheard. He didn't know to whom his words were directed; the only angel who cared about him was downstairs with his demon brother. He doubted God was listening. Even so, he stared down at his clasped hands and whispered his confession.

"I've killed innocent people. Tortured them. I've lied. Cheated. I've stolen. I made a deal with a demon. I've turned my back on my friends." He swallowed hard, trying to keep his voice steady. Jodi had left him so many voicemails. His response had been to chuck his phone. He clasped his hands tighter, watching his knuckles whiten.

"I've tricked people into helping me, and in doing so, a lot of them died." He sniffed as tears began to form in his eyes. "I don't even remember their names. I kil –" The words caught in his throat and he closed his eyes against their weight. "I killed my friend Kevin." He clenched his clasped hands together as the old nightmare played itself behind his scrunched up eyes and he hung his head and shook in the half-light. He had done so much wrong.

With a great sniff, he continued, his voice barely audible and the words contorted by his constricting throat.

"But the worst thing I've done," he choked, feeling his nails bite into the backs of his hands, "is let my brother become a demon. I let him become his worst nightmare. The thing we both hate more than anything. I – I let his eyes turn black." Tears escaped his closed eyes and ran down his cheeks as though trying to escape the shame and guilt that was consuming him. In all this time, he'd never spoken these thoughts aloud. He hadn't had anyone to speak them to. They had swirled and festered deep inside him like a poisoned storm. Although he had faced some of these black thoughts in the hospital, their strength still surprised him.

"If I had just stayed with him, i-if I hadn't pushed him away –" He took a deep, ragged breath, opening his eyes and staring at the huge, wooden crucifix on the wall before him, begging it to understand. "But I was so angry. And I wanted to hurt him. So I sent him away, and he got hurt. Hurt bad. Because I didn't take care of him. Of my big brother."

He hung his head, tears leaping from his lashes to the grey floor below. Tiny suicidal droplets.

"My brother. I let him down. I didn't look out for him. He's always had my back and I let him die.

"I couldn –" He faltered. "I couldn't get there in time. And I couldn't bring him back, I wasn-wasn't fast enough. I wasn't strong enough. And since then, all I've done has been evil. I deluded myself into thinking the ends justified the means, that if I could just bring Dean back, all the pain I'd caused would be forgotten. But it's not."

He shook silently in the near darkness of the long-abandoned chapel. The walls he had painstakingly built around his conscience were crumbling down and he couldn't bare it. All these things he had done. How could the ends possibly justify such inhuman means? How could he be forgiven for all the hurt he had caused? If Dean were himself now, if he were here, he would be so disappointed. He'd be so angry at him.

"I'm sorry," he sobbed. The whispered words were choked by shame, shaking in time to his trembling shoulders.

But Dean would forgive him – he knew it. Because he would understand. Just as Sam understood that all the pain and terror Dean had caused over the last year wasn't really his fault. His Dean would never stand by while demons murdered untold innocents. His Dean would fight with everything he had to save all those people who neither knew nor cared what it cost the Winchesters.

If Dean could see him now, shaking with silent sobs, hunched over and tear-stained, Sam knew there wasn't anything he wouldn't forgive his little brother. Dean would go to the ends of the earth to save his Sammy pain. And when he returned, battered and bleeding, he would smile that indestructible smile and shrug his shoulders and tell Sam that it had been nothing, that it didn't hurt, that he was family, end of story.

A small smile twisted Sam's salt-wetted lips as he pictured it. Dean would forgive him, no matter how hard it might be.

Sam just needed to get him back. He needed his big brother back to make everything okay again.

They kept each other human, and now it was Sam's turn to remind his brother who he truly was. A good man. A righteous man. A caring, gentle soul who would rip wild hellhounds apart to save someone he cared about, then laugh off the deed as though anyone could've done it.

Taking a series of deep breaths, Sam waited for his emotions to calm. Dean needed him to be focused now. To bring him back. He was Dean's only chance, and he would not fail him again.

Sam blessed himself and wiped his tears from his face and chin. He felt drained, and yet also oddly light. Cleansed, even. He remembered the sensation from trying to cure Crowley, and so assumed his brief confession had, miraculously, worked.

Before he stood up to leave, Sam whispered two fervent words into the impassive stillness.

"Thank you."