There is so much, on this planet. Too much for anyone, other than God, perhaps, to understand. Heaven is a place of simplicity, of absolutes; of beauty, but a beauty of clean lines and white light. Earth is chaotic and ugly and incomprehensible, in all of its vast, unfathomable detail, and the sum total of that inconceivably complex mess is a beauty which transcends Heaven's clean, simple perfection as a master painting does a cartoon.

And Castiel is learning. He knows that to understand all of Earth and of humanity is utterly beyond him, but he is walking among humans and catching at the edges of their vastly complex society, and even this shallow understanding continually astonishes him. Human music shocks him into a transfixed silence the first time he hears it: melodies and cadences, chord progressions, which should be a simple mathematical concept and yet somehow reach into him, drawing out emotion in an almost physical sensation. (He tries to explain it to Dean, who laughs and tells him he's overthinking it.) The way that humans write, shaping words like silver to a clarity and definition and at the same time an elusive complexity beyond the simple do this, go there Enochian absolutes to which Castiel is used. The very concept of fictional characters amazes him: these…yes, these people who exist in a thousand subtly different conceptions in a thousand people's imaginations, with no concrete reality, and yet can have all the complexity and fascination of a real human mind. (When he tells Dean this, Dean allows that overthinking literature is accepted behaviour and offers to lend Castiel some books.)

With every second he spends on this planet, Castiel is becoming more convinced that he has done the right thing, that Earth deserves to be saved. Which is why it comes as such a shock when Dean clicks off the TV in a motel room, turns to him and says, 'Do you ever wonder whether we should just let it happen?'

Castiel frowns.

'Give up. Let it all end, Cas,' Dean elaborates.

'No,' Castiel says. 'I was under the impression that we were trying to prevent that.'

'Oh, now you get sarcasm,' Dean says, and drops back onto the bed he was sitting on, staring at the ceiling with storms in his eyes. He turns the TV remote over and over in his hands. 'Seriously, Cas. There's so much on this planet that shouldn't be happening. Why are we trying so hard to save it?'

'Is this because of the news story?' Castiel queries. Just before Dean turned it off, a solemn-faced woman was sitting behind a desk, talking about a sixteen-year-old girl who had been raped and murdered in Idaho. Castiel wasn't paying much attention; it didn't seem relevant. He had assumed Dean was only watching to pass the time.

'Yeah, I…Not really. Well, sort of, I guess.' This is not an answer, but Castiel is becoming used to this sort of response to clear yes/no questions. Apparently it is a very human trait. Dean sighs, scratches his left shoulder. 'Find God yet?'

'If I had, I would have considered it important enough to tell you.'

Dean rolls his eyes. 'Do you really think it's going to happen?'

'I think I have a chance.'

'What if you do find him and he tells you to fuck off?'

'You have no faith,' Castiel says. He looks at Dean more carefully. 'Have you been drinking?'

He knows the answer. He has been checking in with the Winchesters once or twice a week since he left Heaven (ostensibly to check for any progress they have made in the so far unsuccessful research into how to stop Lucifer now the Colt is not an option, even though he knows that Dean would call him immediately if anything important came up. In all honesty, Castiel misses the security of having an anchor, a command, a concrete connection to his allies and his duty. Angels were not made to work alone, and as he travels the world in search of his Father, Castiel would not deny that, sometimes, he feels lonely.) Through the course of these visits, there have been few occasions on which Dean hasn't been drinking.

'Oh, so I'm not allowed to hate the world when I'm sober?' Dean says caustically. 'Look at us, Cas. The world's full of murderers, and dictators, and…What'd be so bad about letting your brothers all clear it up?'

'The murderers and dictators will all be dead in a hundred years whether or not you allow the Apocalypse,' Castiel points out. 'Humans are brief. Can I ascribe this pessimism to your conversation with Michael?'

Dean sits up sharply. 'I can have an opinion that your jerkass brother didn't put in my head, Cas.'

'Of course,' Castiel says diplomatically.

'Did you…' Dean rakes a hand through his short hair. 'Did you know Michael?'

'I have met him.'

'What's he like?'

Castiel's eyes narrow as he scrutinises Dean. 'Why do you want to know?'

'Jesus, Cas, just humour me, okay? What's the guy who wants to ride around in me smiting the Earth like?'

'Michael commands Heaven in our Father's absence,' Castiel says, choosing his words carefully. He does not want to give Dean any ideas. 'He is the strongest of our warriors.'

'Stronger than Lucifer? He kicked him out of Heaven the first time round, right?'

'Yes,' Castiel says shortly. He does not like to remember that time. None of them do. It is a stain on Heaven's history. 'Michael is very devoted to our Father. More so than most other angels. Especially Raphael,' he adds. Dean smirks, presumably at the memory of the Raphael incident. Castiel tends to think of it with more apprehension than humour; at the time he was flying on the tails of Dean's recklessness, but he suspects he will come to regret it. 'He is very committed to what he sees as his duty.'

'Maybe he's right,' Dean says quietly.

'He isn't,' Castiel tells him, more worried than he would admit to that Dean, of all people, is having such doubts. 'Until your encounter with him Michael had not taken a vessel for millennia. If he knew more of Earth, he'd understand that we can't let such…we can't let it be lost.'

'What's so great about us?' Dean snapped. 'I mean, Jesus, Cas, I'm supposedly the Righteous Man, and look at me. If I'm the most righteous person you could find, what're the rest of us like?'

'That's not how it works.'

'Yeah? Enlighten me.'

'You were the most righteous person who went to Hell,' Castiel says curtly, and some of the aggression snaps out of Dean's face. He looks hurt. Castiel feels a spike of guilt in his chest, and uncertain of how to fix things he moves over to the bed and sits down beside Dean. 'Earth is flawed,' he says. 'Humans are flawed. You look at these news stories about people who have done horrible things and you think that they define humanity, but it's more than that. The good people and the monsters of today will all be dead in a few decades, but humanity will still be here. Humans are sometimes good and sometimes evil, but the human race as a whole is…above that.'

'Easy for you to say,' Dean says, low and irritable.

Castiel raises his eyebrows. 'No, Dean,' he says, coolly, 'actually, it wasn't easy for me to say. If you remember, these views have, in fact, caused me quite a few problems.' He sees the guilt rise in Dean's eyes, and continues. 'I gave up my place in the universe's natural order because I could see that Earth was worth more than to be a battleground. You have no right to decide to destroy everything you're, we're fighting for because you're feeling drunk and misanthropic.'

'I'm not drunk,' Dean says quietly.

'You're no more drunk than usual,' Castiel corrects him.

Dean glances at the mostly empty bottles on the bedside table, opens his mouth to say something, and decides against it.

'Don't say yes,' Castiel says shortly.

'I won't,' Dean concedes. 'Okay, Cas. You go find God. Try prison, I hear that works.'

'I don't think God is in prison,' Castiel says, deadpan, face serious, his scripted response to Dean's weak jokes. He's heard this one before; he knows his lines. 'Tell me if you and Sam discover anything important.'

'Sure,' Dean says, sounding as though he's on autopilot, and just before Castiel leaves he sees Dean's hand move, presumably reaching for one of the bottles which isn't quite empty.

I gave everything for you, and this is what you give to me.

Castiel looks down at Dean's bloodied, broken face, takes him back to Bobby's house raging with silent fury, and thinks of that motel room.

Hours later, when he cuts into his vessel's chest, draws in breath sharply, thinks that pain inflicted on this human body has never before been so…immediate…and recognises it as another sign of his deteriorating strength, he is still wondering whether, if he'd found the right words then, he could have shored up Dean's certainties, prevented him from breaking.

Probably not, he thinks. Humans, after all, are flawed, and some more than others.