Sometimes he feels guilty, but mostly he's just lonely. [Written for the Angst_Bingo prompt 'post-apocalypse'.]

Spoilers for series five. It gets a bit AU after that.

This is technically part of a series. The story I'm writing for the prompt 'Arguments/Fighting' is basically the twin sister to this one. Two halves of a whole, if you like. Both can be read alone, though.

It's morning, grey light filtering through crappy motel curtains. Dean feels the weight on the

bed shift, a slight draught as the thin duvet is pulled aside and carefully replaced, the cheap mattress settle. Shuffling sounds, like someone trying and failing to get dressed silently.

"You're going already?" he mumbles. The voice that answers isn't deep and calm like he expects. It's tired, sad, slightly higher than he's used to.

"Castiel's gone back. There's still so much to do. He won't be back for some time."

"Oh." He sits up, focuses on the half-dressed man, who flashes him an apologetic smile. He stats feeling guilty that the man isn't at home with his family.

"I'm sorry, Dean." Novak picks up a newspaper on the motel's kitchen table. "This yesterday's?"

Dean nods. Tries to look at anything other than Novak and his lack of Cas-ness.

"Right." Novak finishes getting ready. "We're in Nevada, right?"

"Yeah." Dean nods. "I'll give you a lift back home. A couple hours driving is the least I can do for you. If you can give me a couple minutes, we can grab breakfast at a diner on the way."

"Sure." Jimmy nods, carefully not looking at Dean directly.

"I have to go see Bobby, anyway."

"Wrapping up a hunt, huh? Demons still around?"

"Not so much. More ghosts and urban legends. Mythological stuff, you know the drill."

"Ah." Jimmy nods agan, pretending to understand what the hell is going on. Bends enough to tug on shoes. "See you in a minute."

The door shuts, and he's left alone. Again.

...

One night, Cas leaves without warning. Jimmy is once again left to say goodbye, the two of them awkwardly making apologies, skirting around what both want to say.

This isn't working. The end of the apocalypse was supposed to make our everything better, not destroy our lives.

Before Jimmy leaves, he turns and says the one thing that messes with Dean more than anything. The guy's just trying to help, but it doesn't do much except fuck with his head. And his heart.

"He really, really loves you."

...

He seems to have developed a sixth sense when it comes to Cas. He knows he's there without even turning around.

"Hey," he says, smiling as he cleans his guns. "I missed you."

"And I you, Dean. There is a pressing matter at hand." He sounds so serious, so Dean turns his head slightly to look back at him.

"What pressing matter?"

"Jimmy and his family. They have been found."

"Found?"

"Demons."

"Shit." He doesn't ask why Cas wants him there, but he grabs some equipment and Cas flies them over before he can insist on driving.

"Ji- Castiel!" Amelia gasps, when they arrive. She's barricaded herself and Claire into the basement and the doors are shuddering. "You left us to get him?"

"You will understand in a moment." Castiel doesn't have to gesture for Dean to know what to do. They decimate the desperate demons in seconds. Cas brands- no, etches- Amelia and Claire with demon-repellent sigils, half-explaining that the sigils are part of their skeletons, much to Amelia's horror and Claire's morbid fascination. Then he turns to Dean.

"I cannot carve the sigils into Jimmy while I am using him as a vessel."

And he understands. Shrugs. It's Cas.

"How can I resist those eyes?"

And then there's brightness and whiteness. There's a weird mix of half-burning, the brightness is almost too much and peace, softness, almost a dream. He soon doesn't want it to end. It does.

He wakes up in his motel room, immediately dialling Jimmy Novak's number.

"Is that what being Cas' vessel is like?" he demands, breathless, spewing his own garbled version of what happened.

"Dean? Yeah, that's what it's like." Jimmy's probably raising an eyebrow, mouthing a desperate i dont know at Amelia.

"All the time?"

"Yes. Why? Are you-" Dean hangs up, torn between guilt and elation.

...

Cas next appears after three long, tedious, horrible months. They spend an entire week together, doing couple-y, romance-y things. Cuddling. Eating. Kissing. Watching movies together. (Dean chooses erotic films and explosion-filled action. Cas picks plot-heavy thrillers and depressing movies.)

"I'm not watching that. Sam saw it a couple years back, took hours to stop bawling like the baby he was. Choose something less emo."

"I did not object to your Busty Asian Beauties- Japanorama."

"I'm not spending the next couple days crying my eyes out because you're feeling like self-harm." He gives a little grin, to show he doesn't really mind, not nearly as much as he says. "Figure of speech, by the way."

Cas doesn't reply for a moment. He slowly lifts his head to stare at the ceiling.

"Cas?"

"I have to leave."

And Dean understands. Cas doesn't appear again for almost eight months. Eight unbearable months. Jimmy is apologetic as always and Dean wants to beat the crap out of him, to demand that he stop being so fucking sorry for Cas' workload, he's the one who should be sorry, not Jimmy.

He doesn't.

...

"When will you be done?" he begs one night as they're lying together. "With fixing everything? Tell me it's soon. It's gotta be soon, right?"

"I do not know."

He sits up, glares down at the angel. So suddenly angry he can't even articulate.

"Y-you don't- you..." Closes eyes, takes a deep breath. "You don't know? Not even a guess?"

"I realise it's an unsatisfactory answer. Unfortunately, it's the truth. I may never be done."

Dean is silent. Gets up, starts dressing.

"Even if my work ended tomorrow, our relationship would not be so different. I trust you and I love you, so I am able to leave you as I must. I am able to watch over you so that you come to no harm. Why is this so difficult for you? Do you not feel the same?"

"I..." he begins. Can't say yes or no. Both are wrong. So very, very wrong.

"As long as I am saving your world, you will always come second, no matter how much I want it to be different. I am the creation of my father first and foremost, and so are you. We owe him so much."

He already knew that.

"Do not fear. I love you. I am doing this for you. I will watch you always. And when you die, you shall be with me in Paradise. You know this."

That's so far away. Suicide is out of the question, or maybe that only goes for Catholics. Even if he did die now, Cas would still be popping here-there-everywhere until his work was finished. He'd be walking around in stupid memories of him fixing his family, how fucking unfair his best moments are making other people's worst less unbearable.

He doesn't say a word. Cas is gone, presumably to drop Jimmy off for once on his way back up to heaven. He almost wishes the end of the world was still nigh. Nothingness is preferable to this fucked-up limbo.