When he is broken, Dean stays away, leaving him with only Meg. She's his female, albeit demonic counterpart so Castiel himself isn't surprised when he kisses her.
It lasts for exactly sixteen seconds before she pushes him away, muttering about not taking advantage of patients. He laughs.
Even his replacement doesn't want him.
...
When he dies, the last thing he hears is Dean's voice and when he opens his eyes, the first thing he sees is Dean in all his glory. And it figures that his heaven would include him, but it's ripped away from him as soon as he takes in his surroundings.
He is alive.
...
As Dean tells him that he can't stay, he feels a detached version of both disappointment and acceptance. Of course Sam is Dean's first priority, he always will be and Castiel knows that. But he just wants, irrationally and selfishly wants, to be the priority just once.
...
"Cas, don't ever change."
And he can't help the small smile that steals across his face at this request. They are in the middle of the apocalypse and this stupid, reckless boy who is everything is telling him not to change.
The headlights on a passing car illuminate Dean's face and he is so beautiful in that moment that he just wants to scream "I love you" into the sky, in his face, until he understands why. He wants to kiss him.
But he doesn't.
Instead he just says, "Okay."
...
He is washing his face by the river when he hears his name being called. He turns towards the source of the sound and oh God, he thinks he's going to be sick.
There's Dean with an unknown companion traipsing towards him. He stands, hoping this is a hallucination and then Dean's arms are around him, whispering iloveyousomuchwherethehellwereyou in his ear, and he doesn't know if he's been placed in Heaven or Hell.
...
He finds him standing next to a street preacher and he thinks he might destroy the whole town.
He rebelled for him, he killed his brothers and sisters for him and he goes and does this.
When Dean is on the floor, bloody and defiant, Castiel thinks he just learned how love and hate run in the same vein.
...
He breaks Dean's arm, silently marveling at the sound as he falls to the ground. He ignores the pleading as he stabs him.
The light in the warehouse flickers on and he senses rather than hears Naomi's approach. Her words wash over him as he stares down at the body with clinical interest. Slowly, he looks up at the rest of the bodies.
He sees the one that he smote, the one that he'd shot, and hundreds of others.
He feels nothing.
...
They warded the barn, he notices. It's a shame that they used the wrong ones.
He enters easily and is welcomed by looks of shock. Quickly, looks of shock are replaced by defiance.
"Who are you," the human-Dean-snarls. Castiel regards him with clinical interest. He did a good job reassembling him but there are still some cracks that he can't reach. But that's irrelevant as long as he can still serve.
"I am the one who gripped you tight and raised you from perdition."
"Yeah. Thanks for that." He plunges his dagger into Jimmy's chest.
Inside, Castiel smiles. He just might like this one.