They tell Castiel about the spell the day after he returns to the bunker.
At first, the ex-angel stares at them for a good fifteen seconds in shocked silence. His lips part, a sentence just waiting to be released, but for some reason he can’t get his tongue to cooperate so he just stands there, mute, his mouth agape. Thoughts and questions zip through his head in muddled clouds and hum ceaselessly in his ears, more deafening than the cries of his siblings just after the Fall. He doesn’t know which ones to heed and which to ignore, and there’s some strange pressure building up in his chest, pressing against the inside of his ribcage and he feels very strange all of a sudden and something is very very wrong and his eyes sting—why are his eyes stinging—
"What?" is the only word Castiel can manage to force past the wad of cotton that has somehow lodged itself in his throat. He feels dizzy and oddly phantasmal, as if he were watching himself from a distance.
Sympathy and sorrow and pity fall like shadows across Dean’s face at the sound of his friend’s weak, quavering voice. He looks over at Sam a few feet away; the expression is mirrored on the younger man’s features.
"Cas, we…we’re so sorry," Sam says softly, his voice all too loud in the sudden silence of the bunker’s dining room.
Dean’s gaze returns to the fallen angel and his heart clenches at the unfettered brokenness in those once-bright sapphire eyes. Castiel had been so happy to return to the bunker, to hunting; he’d been so eager to discover a way to return his brothers and sisters back to their home above the clouds where they belonged. He’d looked like he had a purpose again, and Dean had been so fucking happy for him…
…until he’d remembered the news they’d had yet to tell him.
Now that that news is out there, Cas just looks lost again. Dean gets up off the table he’s been sitting on and takes a few steps towards him, his hands itching to touch Cas’s shoulder, his face, somewhere on his body to provide comfort. “Buddy, hey—”
But the fallen angel backs away from the advance, a stricken look of disbelief and anguish on his face. He blinks, and all at once a pair of heavy tears fall from his eyes and track down his flushed cheeks—Dean is surprised at himself for not seeing them welling in the blue depths beforehand. Cas holds up a hand as if to shield himself from an attack, and Dean stops in his tracks.
"I…I can’t…" Castiel’s weak attempt at speech fades into an echo in the large room, and he gulps. Another tear trails down his face just as he turns and flees, heading down the corridor to his new bedroom.
Immediately, Dean shifts back in gear and follows him. “Hey, hey, Cas, wait,” he calls almost desperately, but his friend breaks into a run and turns the corner before Dean can reach him.
The faint sound of a door slamming reaches Dean’s ears a few seconds later. He’s left standing in the hallway, one arm outstretched, staring at the spot where Castiel had just disappeared from his view.
Footsteps sound behind him a moment later, and he feels a heavy hand rest on his shoulder. “C’mon, Dean,” Sam says gently, “give him some time. He just found out that there’s no way to fix the biggest mistake he’s ever made—”
"But it’s not his mistake,” Dean interrupts, his eyes still fixed on the bend in the hall. “He’s not the one who did this, Sam, it was Metatron. Cas, he—he was tricked. None of this is his fault.”
Sam’s hand gives a squeeze. “I know,” he sighs sadly. “But I think it’s gonna take more than just hearing you say it for him to believe it.”
Dean turns to face the taller man, staring at him for a moment. “Do you think I should still try?”
"Hell yes. If there’s anyone Cas’ll believe above anyone else, it’s you, Dean. Just…give him a few hours to sort things out, get his head straight. Give him space."
Sending one last look over his shoulder towards Castiel’s room, Dean heaves a sigh of his own and nods. “Alright,” he says reluctantly.“‘S probably a good idea—don’t want him flippin’ his shit on me.”
"Oh, he’s gonna do that anyway," Sam says with a grin. "But if you wait a while, it’ll probably be less…"
They head back to the dining room, and Dean waits.
Six hours later, and the clock is striking 2 a.m. Sam’s been in bed for about an hour, but he hadn’t left without urging Dean to “leave it until morning; see if he comes out for breakfast.” Dean had agreed, of course, but his fingers had been crossed behind his back.
See if he’ll come out for fucking breakfast? The dude’s traumatized. Fuck it, Sam, I’m going to him now.
Tossing aside the Rubik’s Cube that he’s been fiddling with for the past forty five minutes, Dean sets off for the fallen angel’s bedroom.
When he arrives, he finds the door locked as he’d expected. He hazards a knock. “Cas? Buddy? It’s Dean.”
No response. Not even the rustle of fabric can be heard.
"Cas? C’mon, man, lemme in."
"Please, Castiel, I gotta know if—"
"Don’t call me that."
The muffled voice is so faint, so rough and dry, that Dean has to strain his ears considerably to make it out. Pressing the side of his head to the slightly warped wood, he replies, “What was that?”
Silence. Then, “Do not call me Castiel. I don’t…I don’t deserve such a name.”
That’s it. Dean slips his trusty lock pick out of his pocket and fiddles with the tumbler under the antique doorknob for a matter of seconds before it gives way.
The sight that greets him as he enters the scantily-furnished room is expected, but still unnerving: Castiel is seated on his bed, still dressed in his new jeans and faded T-shirt, with his legs folded up against his chest and his head buried in his hands. His fingers have tangled themselves in his hair and are pulled taught, almost certainly causing pain but being masked by the numbing power of grief. He appears not to have moved in the six hours that he’s been cooped up in here.
Dean approaches the bed slowly, almost afraid to startle his friend. “Cas?” Carefully, he sits on the corner of the mattress and leans down to seek out Cas’s face. “Buddy, can you look at me?”
The fallen angel shakes his head silently.
"C’mon, lemme see those baby blues that I’ve missed so much, huh?"
Another head shake, accompanied by Cas drawing his knees even closer to himself.
Something about the way Dean says it must trigger something in Castiel, because after a few more seconds of hesitation he slowly lifts his head. His eyes are puffy and red, his cheeks are flushed, and dried tears that were not brushed away saturate the skin of his face. He looks so much like a child that he’s almost unrecognizable, and Dean’s chest tightens.
"What do you want?" Castiel asks softly, his voice like gravel against sandpaper.
"I wanted to talk to you," Dean replies honestly, shifting minutely closer to the other man. Thankfully, Cas doesn’t back any further away. "I was, er…worried about you, I guess."
"That’s very touching." There is no emotion behind Castiel’s words whatsoever, and he drops his gaze from Dean’s. "Why anyone would worry about me is beyond my understanding."
"Whaddya mean?" Okay, okay, we’re getting somewhere.
It takes a few seconds for Castiel to respond, but when he does it cuts through Dean like an angel blade: “Because the world—the universe—would be better off if I had never been created.”
He says it so flatly, so plainly, as if anyone who does not believe the same is an idiot. Dean feels his pulse accelerate—he’d known Cas would get low after a blow like this, but suicidal? This was not his angel.
"And why the fuck do you think that’s true?" Anger comes through in Dean’s voice when he says this, and he feels justified in it.
Castiel sniffs, and his swollen eyes dampen again almost instantaneously. “Because all I do is fail.” He sobs once, and a single tear slips free. “All I do is ruin my Father’s creation, both here and in Heaven—first I rebelled against it, then I practically destroyed it by vaporizing thousands of my own kind, of my own brothers—and now—” His head drops back into his hands as his shoulders start to shake.
Silent sobs wrack Cas’s weakened human frame, and Dean’s heart finally cracks in two. At the same time, righteous fury wells up within him, and he scoots on the bed so that his side is touching the other man’s leg. Placing a firm but gentle hand on that knee, Dean says intently, “Listen to me, Cas. None of that shit—none of it—is your fault. It never was. You were always being influenced by someone or something evil; you never did any of it because you meant to.”
"But I still did it. I did. My face was the one on that security tape from that campaign party…my blade killed Balthazaar, Samandriel, thousands mor...my Grace…” Castiel shuts his eyes tightly, choking on his tears. “M-My Grace was the final ingredient to make my brothers fall, and I c-can’t fix it. I can’t fix it…” He collapses in on himself, silently crying into his arms braced on his knees.
The hand there shifts to Cas’s shoulder and holds tight. “It ain’t yours to fix,” Dean insists, his voice quieter in the wake of his friend’s pain. “That not-so-holy sonuvabitch Metatron is the one to blame, Cas. It’s his godforsaken spell. He’s the one that’s gotta pay his dues and repair what he fucked up—it isn't your fault at all.”
"I was still an ingredient." Cas’s voice is getting smaller and smaller with every word he utters. "I was the only angel who trusted him and knew where he was—I was the only choice. I-If I hadn’t trusted him, if I’d listened to you, Dean—”
"—Then that dickbag would’ve taken Naomi’s Grace, or one of her lackeys’, or someone else’s." Dean struggles to catch a glimpse of his friend’s concealed face again. "He knew what he wanted; he’d been planning it for fucking millennia. He would’ve kept going until he found someone else, Cas, trust me."
For a brief moment, it almost seems like Cas believes him. His shaking calms down slightly and he lifts his head to sneak a glance at Dean’s face. Hope flares in the hunter’s chest, and he tries to get Cas to return a small smile.
Then Castiel sniffs. “That doesn’t excuse anything else I’ve done,” he whispers, his watery gaze falling from Dean’s once again. “Doesn’t excuse any of the other lives I’ve taken, the other worlds I’ve destroyed…” He shakes his head in despair and sighs, utterly defeated. “Honestly, Dean, you and your brother are constantly repairing my mistakes, cleaning up after me. Ever since you first came into contact with me…Name one instance that you know of where I didn’t fail someone. One instance.”
And that? That’s an easy one. Dean doesn’t even have to think before he gently takes hold of one of Castiel’s wrists and tugs his hand away from his sodden face. He pointedly places the hand on his own chest, right over his heart, and spreads the shaking fingers. His pulse beats under Cas’s palm, strong and slightly elevated.
Emerald eyes lock with sapphire, and Dean murmurs simply, “You saved me.”
Something in the fallen angel’s face changes, and Dean knows he’s struck the right chord. He runs with it. “You’re the one who gripped me tight and raised me from perdition. Your wings were burned by hellfire as you fought for decades to find me. Your hand branded my shoulder when you pieced me back together with your own fingers. Your Grace guided me out of the Pit. Your sacrifices brought me back to Sam, which led me to save him from sucking demons dry, which saved his life, which meant that he was around to help me and you stop the fucking world from ending. Cas…” Dean reaches out and cups his eternal angel’s face, and he smiles. “That was all you. No influence, no possession, no spells, just you and your own free will. You didn’t destroy the world, Castiel, you helped save it.” He tilts his head in a friendly mockery. “And now you don’t think you deserve to be saved yourself?”
It takes a moment for Dean’s words to sink in. But when they do, something in Castiel just breaks. He lets out a single sob, lunges forward, and presses his lips heatedly to his hunter’s.
Dean’s eyes close, and he kisses back with everything he’s got. Because Castiel, Angel of the Lord, is fucking worth everything he’s got. And he might finally believe it.
The next morning, they come out for breakfast hand-in-hand.