The first time Dean kisses Castiel, it’s unexpected. Cas is collapsed on the ground, blood splattered across his beloved trenchcoat, angel blade clenched in his hand, his eyes slowly blinking open as he wakes into consciousness. The fight was intense to say the least, and Cas is fully capable of handling a few dozen demons. But when Dean rushes forward muttering, “Cas you’re such a dumb son of a bitch sometimes,” and crushes their lips together, he doesn’t protest.
The second time is a few hours later. They get back to the bunker close to midnight and everyone is dead tired. Sam heads off to his room almost immediately, the shower flicks on and runs for about ten minutes, and then everything is quiet. It’s just Dean and Cas and the near silence; it’s deafening. They stare at each other for a few more seconds before Dean breaks.
“I wanna show you something,” he says, hesitantly reaching down without another word, taking Cas’s hand in his own, pulling him up the stairs towards his room. Once inside, he shuts the door quietly and turns to Cas.
“So uh… this is it, and it’s all mine,” he says, gesturing to his room with a grin. He watches Cas wander about the room in a daze, a tiny smile on his face. He stops in front of Dean’s desk, reaches down and carefully picks up the picture of Dean and Mary. Dean’s heart swells when Cas’s smile increases. Sometimes Dean wishes Mary would have been able to meet Cas. She would’ve loved him. She always believed in angels, even when they didn’t. Cas sets the picture down and turns toward Dean.
“It’s beautiful, Dean. Very… you.” Dean can’t help but close the distance between them; he reaches up, running his thumb along Cas’s jaw, leans in and kisses him ever so gently. Being one of the most powerful beings in the universe, Cas’s knees shouldn’t feel weak whenever Dean kisses him, but they do.
The next hundred kisses are shared in Dean’s room, on the bed, in the shower, in the back of the impala, in the front of the impala, against the impala, in dark alleyways during a hunt, in the rain, the snow, while eating at diners despite Sam’s protests of, “Ew guys, I’m trying to eat here.”
And Cas remembers them all. The sweet ones, gentle, soft and so full of emotion and proclamations he knows Dean wishes he could say but cannot utter. The hot ones, desperate and needy, leaving him trembling in a way no angel or human should from merely being kissed. Cas remembers the way Dean’s eyes sparkle, full of devotion and love when they eventually pull apart.
Cas doesn’t think he deserves this; he shouldn’t get to have Dean, not after everything, but he does. However, loving Dean comes at price. Cas knows this well by now, so it doesn’t surprise him. Every day, with every kiss, he feels his grace draining away from him and humanity taking it’s place. Other angels would run away, go back to heaven, leave everything behind no matter how attached they were; they wouldn’t allow humanity invade them.
But Castiel has never been like other angels. He doesn’t hide from humanity, he welcomes it. He would rather live a lifetime as a human at Dean’s side than a millennia trapped in heaven, unable to love him. However, he doesn’t tell Dean about his eventual complete mortality, or the cause of it. He knows Dean would stop kissing him, stop touching him, and Cas doesn’t want him to stop, not ever.
The first time he breaks his ankle during a hunt and can’t heal himself, he simply brushes it off. Dean doesn’t, though and neither does Sam, despite Cas’ protests that he’s “fine, just a little weak right now.” Dean watches him for the next few days like a mother hen, coming to his every need. He makes Cas sit on the couch or the bed, with his foot up and watch TV. He yells at him sternly if he tries to get up and constantly hovers at his side, asking if he needs anything. It’s endearing in a way that makes Cas’ heart warm, but also ache painfully from the knowledge of what is to come. Dean knows that something is wrong but… he won’t talk about it. He has his suspicions of course, but he would rather not deal with the blunt truth of what’s happening to Cas until he absolutely has to.
A few months go by and Cas’s ankle heals completely, and he is back to functioning normally. But things have changed. He has to eat now, three meals a day or else he gets hungry. He learns that human stomachs makes funny growling noises. They make him jump in surprise every time he hears them. He sleeps about three hours a night, low to human standards but… to Cas, he knows he’s nearing the end of his grace. He should be sad, depressed even but… he’s not. He would be lying if he said a part of him didn’t want this. He does want this. Cas hates having to go back to heaven on occasion, especially on depleted grace, which makes the journey back that much harder. But he hates leaving Dean even more. The longer he stays with Dean (and Sam) the more difficult it gets to make routine trips to heaven. He needs Dean, more than he ever imagined he would.
On March 5th he makes his final trip to heaven. Final because his wings, invisible to the human eye have started to molt, leaving piles of dark, ebony feathers all around the Bat Cave. Dean picks them up in large bunches with sad eyes; he knows what’s happening now, but he still won’t talk about it.
Once all the feathers are gone, they won’t grow back. If Cas had to choose the worst part of falling, he would say this. An angel’s wings are a source of pride, they mark stature and rank in a garrison, but above all that, they are a sign of beauty. Cas loves his wings. Many angels were envious of them; they were near perfection. He will miss them immensely.
In heaven he wanders around aimlessly, not looking for anything or anyone. The few angels he happens to see, he says goodbye to. They don’t seem surprised when he tells them why. Cas suspects that they knew, that they’ve always known he would come to this, that he was always headed toward this. With one last glance at his favorite heaven, the autistic man’s garden, he returns to earth. Dean hears him fly in and gazes at him, clearly worried. Cas doesn’t want to tell him, but he has to; he’s nearing the end. He can feel it from within, weakness and mortality taking over, the last of his grace trickling away and vanishing up to heaven.
“Dean, please don’t be angry with me for what’s about to happen,” Cas says, his eyes fixed intently on anywhere but Dean’s face.
“What the hell did you do?” Dean asks, crossing to Cas and grabbing onto his arm when the angel suddenly staggers sideways. After a few seconds, Cas raises his eyes to Dean’s and replies, “I made a choice.”
Falling doesn’t hurt, not like he had been told it would. There is no agonizing pain, no tearing of wings from his back. Instead, he feels his entire body give out, all of his muscles collapsing in one instant, causing him to fall to his knees. Dean is beside him in a second, holding him up by his shoulders. Dean’s eyes are wide and scared.
“Are you… falling?” Dean asks quietly, frantically examining Cas’s body looking for, hell he doesn’t know what he’s looking for.
“Yes,” Cas says. Dean raises his head to meet his eyes and Cas sees guilt written in every line of his face. With a loud poof, the rest of Cas feathers topple to the ground from thin air, making a dark, ebony circle around them. Castiel turns his head and sees them, tears welling up in his eyes. His wings are gone. He’s human. He’s not sorry for choosing this; he will never be sorry for choosing Dean. Cas closes his eyes, taking a sharp, shaky breath in. A tear slides down his cheek, and when Dean sees it, he pulls Cas into his arms.
“You’re an idiot you know that? I’m not worth this Cas,” Dean says, holding him so tightly, not ever wanting to let go. Cas stares at Dean in wonder, still in awe that Dean doesn’t understand, will probably never understand, just how worthy he is.
“You’re worth everything,” Cas replies softly, leaning forward and kissing Dean gently on the lips. When Cas starts to pull away, Dean pulls him back in, kissing him with all he has.
This kiss isn’t like all the others they’ve shared. This one speaks of self-sacrifice, undying love and devotion. Of everything they’ve been through, every struggle, every fight against heaven, hell, and purgatory. The kiss is nothing less than the unbreakable bond between a million year old angel and a human who saved the world.
“Therefore what God has joined together, let no man put asunder.”