Secrets never keep, especially not for the Winchesters. Cas knows this, and he knows his secret will eventually be found out. He also knows how pissed they’ll be, especially Dean, so he keeps it to himself.
Then they find Michael. They actually manage to kill him and, for once, there’s nothing else pressing that needs their attention--no rogue angels, no hunts others can’t deal with, no demon problems.
That’s why he finds himself outside Dean’s door that night. He needs help with this, he’s searched through everything he has and he can’t find a way out of the deal. Dean’ll be pissed, but it’s better that he hears it directly from Castiel, so he knocks three times on the door softly.
“Yeah, come in.” The voice that answers him is tired and quiet but undeniably happy. He hates that he’s about to shatter that. Taking a breath, he turns the knob and pushes the door open.
“Hello, Dean. Can we speak?”
Dean’s face lights up as soon as he realizes who’s knocking. It’s adorable, frankly, and he’d confess right now if he was sure the Shadow wouldn’t come for him.
“Yeah, Cas, ‘course. Have a seat.” Dean moves over and pats the bed next to him, so Cas sheds his coat and suit jacket before settling in next to Dean. “What’s up?”
Cas picks at his cuticle, a nervous habit he’s picked up from Dean over the years. “I’ve been keeping something from you.” He can feel the shift in the room when Dean stops breathing. “When I went to Heaven to get Jack’s soul, the Shadow was there, the entity from the empty. It wanted Jack’s soul because he’s a nephilim and thought it owned Jack.”
“Cas, tell me you didn’t,” Dean says quietly. Out of the corner of his eye, he watches Dean scrub a hand over his face.
“I offered to take Jack’s place in the empty so he could return here. I expected to be taken then but… the Shadow didn’t want that. It wants to watch me suffer. So, in my happiest moment, it’ll come and take me.”
“What the fuck, Cas? Why didn’t you tell me? Does Sam know?”
Cas shakes his head; he still can’t bring himself to meet Dean’s gaze. “No, Sam doesn’t know. Jack does, but only because he was there. Don’t be angry with him, I made him promise not to tell you both.”
Dean sighs. It’s a weary, exhausted sigh Cas has heard before and it hurts that he’s the one that caused it. “So what’s our next move? Is there any lore on this thing?”
Cas frowns, finally turning to Dean. “A fair amount, surprisingly. There’s a summoning spell for it, and I’ve gotten a fair bit of information from angels. As far as anyone knows, it predates everything, including God, Amara and Death. It’s where all angels and demons reside post-death, though they’re generally in a cosmic slumber they don’t wake up from. I’m the only one that’s ever escaped that. God has no power there, so whether or not he actually answers us won’t matter. It can shapeshift, it can search your memories with a touch, it’s incredibly strong, and it can possess things. Angels, at least, though I suspect that will hold with other beings as well.”
Dean gapes at him. “You’re making it sound unbeatable, Cas.”
Cas smiles weakly, his gaze returning to his own hands. “I fear that it is.”
Dean’s shoulder bumps against his, so he chances a look at the hunter, who’s smiling softly at him. “C’mon, Cas, when have we ever let something like this win? We’ll figure it out.”
The swell of emotion is what wakes it up. It’s been a year in Earth time, more than long enough for it to have slipped from Castiel’s mind. And now it’s here, his moment of true, shining happiness.
It can’t wait to rip Castiel off the living plane.
But first, he’ll let him have his moment. He’ll let him confess and be loved in return and then take him, leaving his precious hunter heartbroken. Such sweet revenge for being woken up and losing the nephilim.
“Cas, I love you. I have for a while now, I just… I was scared to admit it.” A soft, nervous chuckle escapes Dean’s throat. “I’m tired of dancing around it, who knows how long we have left?”
A delicious bit of irony, in it’s own opinion.
“I love you too, Dean. Of course I do, how could I not?”
It swoops down from the empty, all the way down into that dusty bunker in Lebanon just as the hunter and the angel meet in a kiss. It gives Castiel his moment, feeling all the delicious happiness flowing through the angel’s borrowed veins before reaching out and grabbing onto his grace.
A trap. It should’ve seen that coming, honestly. Of course a Winchester would never go silently, deal or no deal. The taller Winchester is chanting in the first language, the Shadow’s language, and he knows this is it. It hears them. All of them. They’re waking up, the empty will never be peaceful again. The tall one finishes the spell and it feels itself being pulled back to the empty, back to the noisy angels and demons that are now awake and searching for a way out. Unluckily for them and for itself, Sam Winchester just locked the gates of the empty and threw away the key.
“Is that it? Did we do it?” Sam asks breathlessly, eyes darting to his brother and Castiel. A moment of silence passes before Castiel finally nods and grins at them.
“It’s gone. Nothing will be getting in or out of the empty ever again.”
Sam sighs with relief and Dean quickly sweeps Cas into a hug that would be bone-crushing if he wasn’t an angel.
“I’m sorry that was out first kiss,” Dean murmurs, though Cas shakes his head and tightens his grip on the hunter.
“Don’t be. I’m positive we’ll have many more.”
Almost as if to prove the point, Dean leans back and places a chaste kiss on Cas’s lips.
“I should take care of something. I’ll be back tonight.” Cas starts to pulls away, pausing when Dean frowns at him.
“Take care of what? We just saved you, I’d like to keep you safe for at least a night.”
Cas smiles softly, nodding and sliding his hand down to grip Dean’s. “Sam, we’ll be back tonight.”
Sam doesn’t get a chance to say anything before Cas is pulling Dean from the room, heading straight for the garage.
“Cas, hang on, where are we going?” Dean pulls at Cas’s hand, forcing the pair of them to a stop just outside the garage door.
“I’m going to give Naomi my grace.” The look of shock on Dean’s face is confusing, to say the least, and has Cas rethinking his decision.
“What? Cas, is… you don’t have to do that because of me, do you?”
Relief floods through Cas’s system and he smiles easily. “No, Dean. I don’t have to do it at all.” He takes a breath, mostly to steady himself, before continuing. “When I was human, after Metatron… it felt right. It felt like what I’d been missing my entire existence. I had to take my grace back to help, but I never really wanted it back. Now I don’t need it. I figured Heaven could use it. Grace that doesn’t have to maintain an angel at the same time would be far more effective at powering Heaven, and it would relieve the stress of the remaining angels.” Dean still looks confused, so Cas tilts his head as he thinks of a better way to explain. “I can ensure Heaven stays running and be who- what -I really want to be. Human.”
Dean frowns. “You want to be human?”
Cas smiles. “Almost as much as I want to be with you.”
That makes Dean blush, and Cas would be lying if the sight didn’t cause his heartbeat to ratchet up. “You’re sure?”
With a single, decisive nod, Cas leads them to the Impala. “I’m positive.”
Three hours later, they return to the bunker with a newly-human and much happier Castiel and a perfectly functional Heaven.
It’s the best the Winchesters have had it in a while, and Dean sends a silent thank you to Chuck. Not for this--Chuck couldn’t have planned this--but for Castiel.
Finally, for once in their lives, Dean and Castiel get to be unabashedly happy with no looming threats hanging over their heads.