A/N- This was originally written for the Destiel Advent Calendar on Tumblr (which I run, and you should totally check out, because it's got some truly amazing people contributing). It's set at some vaguely AU-ish point in late series 5, is written from Cas' POV and uses italics to represent speech. I hope you like it!

Twelve days, they tell you, there are twelve days to it.

You've only heard of one, barely even understand that, and to learn you were off by a factor of twelve is jolting, somewhat alarming. There are twelve entire days specifically marked for celebration, for rejoicing, for giving thanks and showing love and giving love and showing thanks. It seems daunting, a stretch of time that could swallow a person whole.

The two of them argue over exactly where those twelve days lie until that's it, I'm looking it up, and so they discover that the twelve begin on the day itself and push through all the way into the next month, starting the new year right.

(that's not even Christmas anymore, he argues- I didn't make the rules, Dean, comes the reply.)

But what do you do? you ask.

You give presents, he tells you.

Why do you give presents?

… um.

And you both default back to the one who knows such things, and he tells you Saturnalia, and Dean nods, a sign of ahh, yes, Saturnalia.

Sam looks at him. You have no idea what that means, do you?

No, he admits freely.

Sam sighs, rolls his eyes, and begins his explanation. Back in Ancient Rome-

You only half-listen. You remember Saturnalia- took little note of it, but watched it happen all the same. Sam's explanation is oversimplified and somewhat gentler than the actual festival had been, but it's apt enough.

We don't really do the whole gift thing, Dean explains to you later on, and you nod- I understand- because you were never going to enter a shop, never going to purchase something and wrap it (it needs wrapping?). All the same, silently, to yourself, you decide that you are still going to give what you can, to give all that you have until there's nothing left, because you'd do that no matter the day, you'll do that no matter the date.

And on the first day- the only real day, he argues- you give the only material thing you can think of, one of two crumpled five dollar bills that Jimmy Novak left in his pocket on his last day, on the first day of your second life.

I wanted to give you something. It didn't feel right not to.

And he laughs, as he often does at things you never intended to be funny, but then he takes it and says thanks, Cas, and adds actually, I have something for you too.

He gives you a burger from the restaurant where you once fell into an obsession, a black pit of need that sucked you down deeper with each clunk of teeth. Though the craving for any food has long since died, it still makes you very happy for a reason you can't name.

(Does this often happen? you ask his brother later on, after you hand him the other bill. People promise not to buy gifts and then do anyway?

Pretty much, yeah, he says, and he gives you an angel wing keychain because he saw it and thought of you. )

On the second day, you give him a weapon.

It's for a case and it's something you probably (actually, there's no probably involved) shouldn't have had access to, but you'll deal with that if and when (again, almost certainly no 'if' about it) the time comes. And so you hand the ancient, irreplaceable blade, carved by Michael himself, to Dean, who proceeds to nearly drop it.

Heh, kind of heavy, he says. You close your eyes for a moment.

Once the blade has been successfully transported to the car, they pull on shoes and strap knives to their calves, readying themselves to leave.

He says thanks, Cas, and he looks at you and grins again and holds the gaze until Sam says Dean, we have to go, and he says yeah, in a minute and turns back to you and says sure you don't wanna come along?

I am sure, you say, because what help would you be? Powers fading and reactions slowing, you're nothing but bad news.

He nods. Fair enough. If you change your mind, let us know, and the fact that he still wants you around will never fail to baffle you.

On the third day, you give him reassurance.

He is quiet, staring down the road like maybe if he drives for long enough, he'll be able to leave himself behind, leave his mind on the corner of some dusty highway and become the roar of the engine and the flashing of trees past the window: easier, simpler, cleaner.

You did the right thing, you say, and he seems to snap back into his body at your voice.

I know, he says, but it still sucks.

The man he killed was not a man anymore, but he had been a man once, and you know this is the kind of thing Dean cares about. You don't know the right words and so you offer none, instead sitting in the quietness, looking at him until he looks over at you and his face softens and he says

thanks, Cas,

for the third time in three days, and you smile, you still smile every time he says those words.

On the fourth day, you give him his life.

You and him have fought so many things, so many monsters of dark and old and legend, whispers from stories used to frighten children, demons and angels and Heaven and Hell and you find it laughable, nearly offensive, that a simple werewolf thinks it has the right to hurt him, like after all he's been through a swipe of mutated claws is a fitting end.

The creature crumples dead and Dean falls away panting and you reach out a hand without thinking about it. He looks at it like it's a mystery but takes it all the same and the skin is warm, fingers curling around yours, and you wonder if it was by intentional design that human hands fit this well together.

That was close, he says.

Too close, you agree. You should be more careful.

I should keep you around, he counters, and you are stunned into a kind of silence, and whilst you still know oh-so-little of the human way you think your hands stay joined for longer than is considered customary.

On the fifth day, he saves your life. You give him your gratitude.

It's nothing, he says, hold still.

I'm fine, you say, trying to pretend your arm isn't bleeding because your arm never used to bleed, because you were light and power and clean, pure energy, not a sticky mess of cells and chemicals and feelings and failures.

Like fuck you are. You need stitches, Cas.

It will heal.

Yeah, and you'll bleed half to death by the time it does. Just let me fix it up 'til then. Please.

And you've never learned how to say no to that, and so you hold your arm out and let him place strong hands on it, ignoring the occasional bite of the needle as it sews your gaping edges together.

Thank you, you say again- and then, I'm sorry.

Why?

Because I used to be more than this, you say simply. He puts the needle down, sits back to look at you, and you wonder if you've yet again done something wrong without knowing it.

What grace I have left is weak and waning, you say, to try and make him understand. I'm useless to you.

And your gratitude isn't enough, it can't be, so you try to give him safety instead.

You asked for my help and all I could do was hinder. It's for the best if I stay away from you and Sam.

What? he says, panic clear in his eyes. No!

No? You don't understand.

You saved my life yesterday, Cas, without any juice from Heaven. You don't need your old angel mojo.

What use am I to you without it?

What use? Cas, do you really think I only want you around because of your 'use'?

The simple answer is yes, but you sense that it isn't the right one.

I like you because of you, Dean says. I like you because you're Castiel, not because you're an angel. I couldn't give a rat's ass if you couldn't squash a fly.

Dean, you breathe, but he shakes his head.

I mean it, Cas. Don't you leave. Don't you dare.

I won't, you say.

Good, he says gruffly, now hold still, and he continues sewing and though you barely felt the pain before, now it may as well not be there at all. It's odd, because whilst he's rejected your attempt at offering safety and waved aside your gratitude, you think you've somehow given him something all the same.

On the sixth day, you give him what he asked for.

He's had precious few promises remain unbroken- you yourself have been responsible for the shattering of more than one- so you're determined to show him that this time is different, this time you mean it.

You stay.

There is no fighting, no battle to be won, and still you stay. There isn't even research, no next case and very little to tidy up from the last, but still you stay.

You are a creature of war, used to destroying and avenging, picking up the people you fragmented along the way and clumsily gluing them back together, never breaking step. You are not designed for quiet days in motel rooms, for long hours of nothing but stillness and breath. It is somewhat startling to find yourself at peace, comfortable with being comfortable.

He catches your eye throughout the day and gives you little smiles, and you store them all inside you in a box marked 'for the low days; for the bad days; for when we lose the fight or when the fight was over before we arrived; for when Heaven tell you 'no' and for when they try to tell you anything at all; for when God is great but God is gone'. You store them all inside you and you make sure that they will never, ever be lost.

On the seventh day, you give him a peaceful night.

You look into the room where he lies asleep and you find him thrashing on the bed, strained noises in his throat, eyes closed tight.

Dean?, you say, but he can't hear you. Dean!

Nothing. You scrape around your insides to pull the last wisps of grace into your hands, then place your palms to his head and feel the power trickle away.

He grows still and quiet- settles into a deeper sleep, a calmer sleep. Once upon a time you would have reached inside again to replace what you took with a softer dream, a memory of a better time, but that's beyond you now.

You stand and look at him instead, and as you do so he seems to lose some of the burdens he carries, the deep scars criss-crossing his heart healed or at least plastered over, forgotten for a few clumsy contractions of the muscle. Inside you, an aching absence whispers over and over that you have no grace, you have no grace, you have no grace, but the longer you look at him the less you hear it.

On the eighth day, you give him Sam's life.

As Dean is Dean, you get the impression that this impacts in a way that your care for him does not, that your never-wavering protection of his own life is rendered insipid and meaningless by comparison.

I should've been there, he says, frustrated.

Hold still, you reply, and pull the bandage tighter. You are new to this, but you will learn. You are determined to learn. What were once your resources are now kept in a cupboard you cannot reach, and the times when you could smooth away a cut or burn or break with a simple stroke of your finger are in the past. You cannot heal like that so you will learn to heal like this, because this is what lies ahead and maybe what lies behind is best left there. After all, buried with the days of power and grace are the days of looking at humanity and seeing only a faceless and pitiful mass, days when the words 'righteous man' were nothing more than lines from a fairy story, told to you by patient older brothers.

I should've been there, he repeats, ignoring you.

Dean, you were being held. You nearly died yourself. There is nothing you could have done. You huff and untie a section of the bandage, twisted entirely wrongly against his broken skin. And Sam is fine.

Thanks to you, he says.

That's not of relevance.

Bullshit it's not. He holds your gaze and you hold his. Thank you for looking after him.

You know I would never let any harm come to Sam.

You swear?

You don't understand why he requires verification, but you give it to him all the same.

I swear. Now hold still.

And this time, marking what is quite possibly the first time he's ever listened to you, he does.

On the ninth day, you give him your allegiance.

All of my grace is now depleted, you say, head down, voice low and measured. I'm sorry.

Why? Sam says. You've got nothing to be sorry for.

Don't be stupid, Dean agrees.

You swallow, hard. When I left earlier, it was to visit to Heaven, to speak with my brothers and sisters. As it turns out, it was for the final time. I've been cut off from their voices. I can't hear them anymore. It was made clear I am not to return.

Silence fills the room, a solid, tangible presence.

Cas… I'm sorry, Sam says. Do you know why?

They find my actions deplorable. They consider my allegiance to you comparable to treason.

Wait, so this is our fault? Dean says. Cas, I don't want you to-

It is not your fault, you say, fiercely, and he looks taken aback. If they cannot see the qualities in humanity that I can, then that is their error and I will not have you held responsible for it. This is choice, Dean, not obligation. They asked me to choose, and I chose this. I chose you.

The phrasing refers to both boys yet all three of you know, instinctively, without anybody asking for elaboration as you catch Dean's eye, that the words are meant for him. You love Sam with all your heart, love him as much as you've loved any brother, but your feelings for Dean are of a nature more complex, more unknown, more overwhelming, more amazing.

Why? Dean says, voice hoarse. Why me?

You've seen things recorded in ancient history textbooks, along with things that never were because nobody else was there to see them; you heard the first word spoken and, if you hadn't chosen to fall, you would have been around to hear the last. You have seen every possibility, a thousand potential outcomes of the universe splattered like paint on a canvas, every tomorrow that may be and every yesterday that never was. You have encountered an uncountable number of prospects, and out of the hundreds upon thousands of futures you can imagine, you cannot imagine a single one without him.

You cannot put this into words- not in this human tongue, this strange little language that can possess a hundred ways of phrasing something and yet have none of them be right. Instead of attempting, of stumbling your way through your flawed and formal form of address, you offer Dean only a simple phrase-

Because you are you.

- because you think that, somehow- oh, and this really is such a funny little language- it manages to say the same thing.

On the tenth day, you give him a peaceful night.

Dean. Dean, wake up. You're dreaming.

Cas? he gasps, bolting upright. His hair is plastered to his head, his arms scratched from fighting off phantoms of the mind.

Yes, it's me.

You're okay? You're here?

I'm here, you repeat, because it seems to matter to him. His eyes are wide. You wonder what horror you woke him from and wish you could do something, anything to make it better.

Fuck, he exhales, sinking back onto his pillows. That was… fuck.

It wasn't real, you tell him. Whatever happened, it wasn't real.

You ever dreamt?

No.

Then I guess you wouldn't know that it's not that easy. You look at him, imploring him to continue. He obliges. It feels real, Cas. Sure, it's easy to laugh it away when it's sunny and bright outside, but in the middle of the night? He drifts for a moment, lost in thought. Sometimes I can't tell what's real and what isn't.

You study him and then sit on the side of his wide bed, one hand moving down to rest cautiously on his slumped shoulder. I am real, as is Sam, and neither of us is harmed. You know that.

Yeah, but I'll forget it when I close my eyes.

Then I'll stay here to remind you. He turns to look at you, and you remain still. You mean what you say.

You don't have to.

No, you agree, and you swing your legs up so that you're lying full-length beside him, hand moving from his shoulder with reluctance. I don't 'have' to do anything.

His smile is small, but genuine, and he closes his eyes. Go to sleep if you get tired, okay?

I will, you tell him, but even if you are now capable of sleep, you don't discover it tonight. You stay awake watching him, offering yourself as a familiar rock to cling to in a storm, something to make the pain just that little bit better, and he is calm and quiet until morning.

On the eleventh day, you give him your head; your mind, your knowledge.

What about Jimmy? he asks.

Long-since lost, you say with sorrow. He was not saddened. Heaven was… a relief.

I'll bet. So if you're the only thing in there and you're not a bundle of cosmic chaos anymore, does that make you human?

More or less. There are some things I was left. Memories, mostly. I remember… everything.

I'm guessing that you've been around for a while.

A long, long while.

Tell me about it.

That strikes you as odd. For what reason?

Because I want to know.

And so you talk about the things you've seen and caused and stopped and failed to stop, failures as well as successes, and he listens and sometimes asks questions and you answer them, every single one, and you look at the clock every now and again to note that two, four, six hours have passed, and still the two of you speak, about his life as well as yours, about the weather, about the world, about Sam and sport and God and television programs, and at times you laugh and at times you are solemn, and somewhere along the line you lose track of just who is teaching who what.

On the final day, you are unhappy with the gift you give him. It seems bad manners to give him something he already has, something he's had for a very long time now.

On the twelfth day, you give him your heart.

You are sat talking when the words begin to falter, to fade, and then they cut off unexpectedly in both of your throats, sentences abandoned halfway through

and then slowly

slowly

you are moving forwards, coming together.

Neither of you are men of words- in wartime, perhaps, you could give speeches urging destruction, prompting death, but you have not yet mastered the method by which people reach into their chests and pull out the tangled mess inside into coherent strands of prose. If Dean is anything to go by, this is not a skill that develops naturally as time passes.

And so instead you tell it to his hands with the touch of your skin against his, your fingers brushing together as the gap between you closes. You look at him until you see the things you want to say reflected back at you, and then you move closer to breathe the words against his mouth, to bring them to life with the press of your lips together.

I'm sorry, your fingers say as they flutter up and down his back, unable to stay in one place for more than a moment. For all of it, for all of this, I'm sorry.

Don't be, he tells you back with the steady grip of his hands on your waist, with the insistent heat of his mouth and the soft noises in the back of his throat. There's nothing to be sorry for, nothing, nothing.

I wanted to be more than this, the tilt of your head backwards says, the skating of your fingertips over his arms.

You're enough, his lips on your neck, your jaw, your lips tells you. You're more than enough, so much better than 'enough'.

And then, of course, are the words even harder to say, words that have taken the place of your grace, moved to fill the empty gap in your chest with a brighter glow than ever before.

I love you, you tell him with the folding of your hands into his hair; I love you, with the leaving of your coat on a floor somewhere as your back hits the mattress; I love you with the heavy weight of him joining you, I love you with the cry stifled into his neck, I love you with eyes, with fingers, with toes, with lips, with the crush of torn and callused skin that may as well be silk.

I love you, he tells you back- with his mouth, with his voice, words hanging in the air like decorations on a tree, words that glitter like lights and make a cold night warmer. And your fingers link with his and your legs tangle together, and you think that twelve is really only the start; that there are more days to be had, more things to be given, more things to be gained and more than, more than enough.