When Castiel had been missing, Dean’s idle hands and excited energy brought him to fix up a room for Cas across the room from his. He didn’t want to presume of course, and the lingering doubt as always left a bitter taste souring his mouth, but it was something to do when his own room was arranged and finished, and it helped him forget to think about the possibility of anything but Cas coming back to him—to this.
He assembles a book case and stocks it with his own favourites (he assumes Castiel has read everything anyway, might as well give him something to talk about), but also with some ancient and heavy tomes that not even Sam will try and go near, in languages so old no one even remembers that they’re dead anymore. He finds a desk and a chair, and tries to make it a comfy one, and finds the best light in the bunker to sit at the corner of that desk, propped such a way that is, rather coincidentally visible from the door of Dean’s own room. You know, just so he can check.
Indeed, Dean becomes so preoccupied with crafting the perfect space for Castiel’s bedroom that he entirely forgets to put a bed in it.
"I suppose then I’ll jut have to sleep in yours then," Cas says when he first surveys it, soft smile playing at his lips, and Dean can’t even tell if he’s serious or a making a dry joke in the style that’s become his favourite, but Dean doesn’t even care. He doesn’t care and doesn’t squirm under the bare affection of Cas’ gaze, and instead, returns it right back.
He strides across Cas’ new room and hugs him, and into his neck whispers the best and worst kept secret he has left to tell: “Welcome home, Cas.”
And that, as they say, was that.