The first time is a business transaction. The same way, he will one day learn, a cashier smiles at you as you sort out your newly-packed plastic bags and calls 'have a nice day!' It is a sentiment that means more professional duty.
It's also fortunate Dean's existence is entirely contained, in that moment, in his soul. Castiel's professional Enochian "I love you" splinters cracks through the stones of Hell and makes demons shrink, blacken in their pursuit. The calling-card would have likely caused Dean to bleed from any extant ears.
It was then, focusing behind him at Dean's squirming, disbelieving soul (he had to grip his charge very tightly), haloed by the hairline fractures his professional courtesy left in their wake, Castiel wonders if he should have gotten the hint.
The second time is more acting and promise. Castiel and Dean had gone bar hopping — which is to say Castiel has drunk three bars and Dean staggers to keep pace. Which is to say, Cas is well-within his role of drunken lout, and Dean's sloshed enough to accept anything.
Dean swings his arm across Castiel as Cas watches a man lucky man—who'd gotten the last drink before Dean'd started ordering—swing his arm across another woman to call those words out to the early-rising pigeons and parking lot raccoons. Cas hasn't entirely understood gender roles yet; it's a witching hour and dawn is lining up to roll colors onto the world and Dean has one arm around him just like that other man and Cas figures now is a good time to say it. "I love you!" He cries out, laughing.
Dean pats his shoulder with his other hand, staggering onto the Impala's hood.
Cas is not strictly a man (as much as he is loaning one), and there's something wanting to pull the shutters over Dean's eyes as he expands and shrinks in front of Castiel (or is that his beautiful soul?), but Cas doesn't have much time to assess his reaction when Dean continues, "can you zap us back or will we end up in Aruba or something?"
Cas nods and touches Dean's forehead.
The thunk from the hood of a Ford Explorer and the other early-couple moans through the empty parking lot.
Dean only has enough time to be sick on Castiel's coat before he passes out.
Cas re-hydrates Dean and takes away his hangover before he leaves.
"Cas, what happened last night?" Dean asks later that afternoon, "How many bars did you drink under this time?"
Castiel guesses that, even without the hangover, Dean had too much alcohol in his system to make any memories in the first place.
Dean is in purgatory and Castiel isn't there to reply to desperate, resigned, reflexive, mantra of prayers. "I love you," Castiel prays to him, "I'm sorry."
Castiel remembered when he didn't need to sleep. He also remembered everything that happened in the interim. Some of it was terrifying.
Normally, Sam or Dean would be up too. They had seen many of the same things, some worse. It was natural that they, too, would be visited at night. Even if they never talked about it beyond pouring coffee for each other.
But Dean wasn't. Cas is twisting his neck over the motel's pull-out sofa, listening to Dean snore and re-assuring himself that he didn't wake too loud.
Cas gets up. Because it's 3:46 and Dean wanted to be up by 5:00 and an hour and a half wasn't worth having to rehearse what he would do (would not. not . do) to Dean with Naomi again.
So he rolls off the groaning couch, gets dressed, and leans against the wall, waiting for the July dawn to come meet them and peak through the hotel's torn blackout curtains.
In between Dean's snores, something rises in his chest like the first song he ever heard ringing from the Host. The burning of his wings as he Fell. The waves of heat rolling from an August tarmac. The way Dean glances through the mirror to meet his eyes while he's brushing his teeth. Like something completely different but probably closest to the last one and more overwhelming than the ones between.
It escapes between his lips in a whisper, "I love you."
The alarm buzzes.
Dean groans like the old couch.
“Morning,” Dean slides him coffee across the bunker’s kitchen countertop.
He takes a sip. In the years, he’s gotten used to the taste.
“I love you,” he mutters into his cup. Because it feels appropriate. Because it seems the sort of thing, he’s learned, you say to someone first thing in the morning, when they’re waist-deep in the fridge scrounging for breakfast eggs before their brother walks in with another case and they’re burning pavement, between sips of coffee that are like heaven but kinder, where you feel more at home underground than with a view of every single star your brothers and sisters helped create. Because before he started on the eggs or picked up his keys, he handed you coffee.
Because it’s true.
Dean pulls his head out of the fridge. Closes the door. “Huh? What?”
Cas smiles into his cup. “Good morning, Dean.”
"Dean, I — " he couldn't say it. He had a deal.
Jack, Sam, Dean. He couldn't go yet.
He figured he'd have to break the habit.
"What was that, Cas?"
He needs something to do with his mouth. "Do you have any coffee?"
"Uh, yeah. Sure."
He steals Dean's. Takes a sip.
It had been a long time since he said it to Dean, or to rocks or trees or spheres of creation or anyone. At least he had made a deal, an equal exchange he knew how to keep.
But he didn't need to keep it anymore.
He had to break it.
“Why does it sound like goodbye?”
“Because it is.”
And this time, Dean needed to hear it.
“...I love you.”