Cas never used to smile.
It occurs to Dean while the angel's speaking, his voice low and gentle with concern, urging him to take some time to himself, to rest and recover. He remembers frowns of confusion and countless, endless stares – but he's not sure he remembers the last time he saw Cas smile.
It's barely there, just a flash of something sad and wistful, before Cas turns to go – and all at once, Dean remembers.
It was when he first arrived at the bunker, and it was because of a hot shower and a crappy gas station burrito and the rock-solid belief that he'd finally found his way home – just minutes before Dean had driven that smile from his face and replaced it with hurt and confusion.
Now, Cas is smiling again – and there's something different about it this time, Dean can feel it. There's a quiet confidence that wasn't there before – a calm certainty that Dean doesn't think he's seen in Cas once since the moment he slapped his palm against that bloody sigil on the wall of the Green Room and chose Dean over all of Heaven.
It's there now, though – and all at once, Dean understands. The last time he saw Cas smile, he was smiling because he'd found his way back to Dean.
This time, he's smiling because he's found his way without him.
Something like panic tightens in Dean's chest, and he finds himself clinging to that faint wistful flicker he saw, hoping it's not too late. His door is almost closed when he calls out, "Wait!"
Cas immediately turns, warmth and affection on his face. "Yes, Dean?"
Dean crosses the room to him in a couple of swift strides – then freezes up when they're inches apart, the words he was so desperate to pour out a moment ago unable to find his voice. Cas just waits patiently, his brow creasing slightly with concern the longer Dean goes in silence. Finally, Dean manages to choke out something remotely related to the things he's been thinking.
"I – I shouldn't have made you go. Before, when – when Sam was…" He shakes his head. "I – I was wrong."
Cas's face softens, sympathetic and reassuring when he says, "You apologized to me, Dean. I accepted your apology. There's no need…"
Dean catches Cas's arm and pulls him back into the room, closing the door with his free hand, and Cas glances over his shoulder at the closed door, looking back at Dean with uncertainty.
Dean's heart is racing, his mouth is dry, and he can't find the words for all the things he wants to say. So he just focuses on finding the strength of will to get out a single word, the most important one, the one he wishes he'd said years ago.
"Stay."
Cas's eyes widen just a little, and his breath catches. Dean wouldn't even have caught it if they weren't standing so close. But they are close, and he can see the spark of hope in Cas's gaze before he looks away, gently pulling out of Dean's grasp and taking a backward step. It puts his back against the door, and he swallows slowly. His words are halting and uncertain when at last he replies.
"Dean – you don't have to…" He hesitates, and Dean hates the shame he sees on Cas's face before he forces another smile and looks up. "I'm fine without…"
"I'm not," Dean cuts him off sharply, his words hoarse and trembling. "I'm not fine without you here."
And Cas looks so confused, so guarded, like he's not sure whether or not to trust, and Dean can't blame him. He feels a pang of guilt for the gratitude he feels, just for this moment, that Cas doesn't have his wings right now, can't fly away when Dean shifts in close and places a shaking hand against the side of his neck, thumb tilting his jaw up just a little as Dean presses his mouth against Cas's and kisses him.
It's deep and urgent and desperate and aching, and Dean's trying to say so many, many things that there aren't words for, not anymore, not after everything that's passed between them, but he needs Cas to know…
They're both breathless when Cas finally pulls away, his head lowered so that his brow rests against Dean's, and he shakes his head a little, helplessly, gasps out, "Dean…"
Dean slides his arms around Cas's waist and pulls him in close, grateful at the lack of resistance he feels, the tentative brush of Cas's hands against his sides. He rests his face against Cas's neck for a moment before kissing the spot softly and raising his head, repeating, quiet and rasping in the stillness.
"Stay."
He hardly dares to raise his head, and his stomach clenches as Cas raises his. Dean isn't sure he wants to see what's there – and his chest aches with sweet relief and gratitude when he sees the tears shining in Cas's eyes, over that soft, certain smile. Cas barely nods, and Dean is kissing him again before he's even gotten out the single, soft word of response.
"Okay."
