AN: just a little idea that spawned ~1600 words. I really love the friendship between Cas and Sam, and this is a piece that explores that. Let me know what you think!

Sam was dreaming. He dreamed that he was swimming.

That, really, was what stopped Cas from walking right on by. He'd only come to see Dean, really: he wanted proof that Dean was, in fact, praying to him; that this wasn't just another trick, and he'd actually allowed himself to ask for help concerning his brother.

Dean still thought he was on par with any sort of deity. This was enough faith in him for Castiel, too, to believe in himself.

Cas had chosen to inspect the bunker. It wasn't as well angel-proofed as perhaps they'd have liked it to be; he'd set that right on his way out, lest Naomi send him after the real Dean (and not just the hundreds of fake, broken ones in Heaven).

He'd even allowed himself a small smile when he saw the state of the library: Dean's beer bottles in lazy swarms on his desk along with his scribbled short notes, while his younger's brothers' books lay open with bookmarks, should he accidentally shut them and loose his place.

But on his way out, he'd passed through a corridor on the opposite side of the bunker to Dean's. Peculiar, he thought, that they should want to separate in such a way: in Heaven, for hundreds of years, he'd sought out his brothers and sisters; been close to them. In Heaven, 'close' was relative, as it was a vast an unending realm . . . But he could be with them in a second's thought. That was before, of course, he'd fallen; he'd fought savagely over the most amazing event that had never come to pass: the Apocalypse.

And all for the sake of these two men.

He sensed the presence of a sleeping Sam Winchester even through his thoroughly shut and locked door – which, incidentally, he also found suspicious, as if he were trying to keep his brother out. There was no reason to think that any creature could get to him here: the only one he could be hiding from was Dean.

But the presence that lay inside was different to that which he normally sensed. He remembered communicating with Dean for the first time in a dream; he'd appeared at Bobby Singer's house to speak to the Righteous Man about the rising of the witnesses, and had, coincidentally, registered what Sam's state of mind was like when he slept.

Wracked with guilt, was the first thing that came to mind. Secondly, the demon blood, festering away at the back of his mind, but valiantly ignored and avoided. Thirdly . . . Memories of Dean, both good and bad. Of their father. Of his would-be fiancée. Castiel knew there were such things as tragic characters in human literature and mythology alike: like Orpheus, Sam had been to Hell and back in his lifetime just to save his loved ones; he'd had them snatched away, too, along with several other horrible consequences.

But Castiel didn't know for sure if it was entirely appropriate to refer to real people as tragic characters or not. He supposed that was something humans just knew on intuition.

The conflict came as he sensed something . . . Incorrect, coming from Sam's room; from his mind. Something slightly irregular, that went against the precedent of what Sam's dreams were usually like.

Silently, he reappeared in the dozing Winchester's room, and looked down at him with a blank expression. He allowed himself to be immersed in Sam's dream, to try and figure out what exactly was so different about Sam.

In the dream, playing out in real time, Sam swam at night in a black sea with even, calm strokes. He continued for a small while, but then stopped. Cas knew that humans tended to tire quickly when exerted like this, especially with the extra weight of heavy, sodden clothes; besides, there was no sign of a shore. Sam cast his gaze around, but he couldn't see anything, or anyone. Cas, from above him, watched as he took a deep breath, and let himself slowly drift beneath the surface.

This was not characteristic of humans in general: even in their dreams, they all had an insatiable need for self-preservation. Why should Sam be any different? Why was he different? The angel couldn't comprehend it. He reappeared under water.

Sam sank down, slowing to a stop a few metres below the surface. Castiel was reminded of the sea creatures he'd seen and admired on his travels, as he watched Sam's hair float gently upwards, dark and spreading out like ink in the already dark-toned water. He was slowly sinking, but his face appeared completely relaxed. Castiel frowned, closing his eyes to try and concentrate more fully on what Sam was seeing.

Strange . . . No furrowing of his brow, or tight squeezing shut of his eyes, as would indicate some form of inner turmoil. Totally at ease, or rather . . . At peace.

Sam was at peace.

That was it: that was what Cas had been sensing this whole time; why he felt that the Winchester had changed. Well, not just that – he'd changed on a sub-atomic level, too, and there were odd changes and fluctuations in his electro-magnetic field that were a cause for concern, but that all paled in comparison with how alarmingly calm he was.

The human looked forwards, the water seemingly not stinging his eyes. His shirts billowed slightly, showing skin that was slightly too pale; it gleamed in the light of the moon that was coming from the surface. Cas made sure he wasn't seen.

Sam's mouth parted slightly, and a tiny streak of red floated out between his lips.

Castiel understood, now: this was the calm; the patience; the grace of someone who knew they were doomed to suffer or die, but could do nothing about it.

Castiel thought he heard a whisper of a memory in Sam's mind . . . It sounded like his brother, taunting Sam, saying –

". . . you're actually keeping it together better than I thought. Kind of . . . The way someone pinned under a bus keeps it together . . ."

Despite this undermining, cynical voice, the angel respected that he wasn't panicking: even in the dream, he wasn't worried for lack of air, even though his lips were blue-tinged. Castiel noted how the water wasn't cloying and oppressive to him, but welcoming and embracing, even though he knew he'd have to breathe eventually or he'd die. The angel lamented that the human felt he had to breathe, even in a dream . . . Surely this meant he didn't know he was dreaming.

Sam looked down; Cas followed his gaze, to the gradients of darker blue, followed by black, that were beneath them. He spotted what looked like tendrils . . . No, hands. Distorted human appendages, reaching out to tug at the human's jeans, at his ankles and his bare feet, enticing him to come with them and end it all.

Castiel tried to understand the utter anguish that Sam felt as he glanced once more at the surface of the water before he allowed himself to be dragged down. Cas wonders what he would die for . . . Granted, to save the world from all demons was a noble cause. His mind was cast back to his lessons with Naomi, and he winced, surprising himself with the physical reaction: all the times she'd made him kill Dean.

That was something he'd rather die than do . . . Maybe the only thing.

But then, as he looked at Sam Winchester's face, he wondered if he would rather die than see that look: the one that told the angel that the hunter knew he was going to have to go through the worst imaginable Hell, again, to save the world. Last time around, Castiel had been so desperate to retrieve Sam from that fate that he'd been hasty in freeing him: he'd left his soul behind. This time, he wasn't sure if even he would be able to save him, or even salvage any part of him. He wouldn't be able to heal him from the sort of metaphysical damage that he was inevitably going to sustain.

As Sam was pulled down further and further, the few bubbles of air he had retained slipping from his open, blood-trailing mouth, he grieved for the fact that his Father was so cruel as to test the same man twice. He saw now that Sam was not Orpheus in his previous analogy: he was Orpheus' wife, dragged back to the underworld after glimpsing what his fresh, improved life could have been like. He had come so close to the normal, happy existence that Castiel had always sensed was his greatest desire: that desire was what defined him. Without his soul, he hadn't had it, leading the angel to conclude that Sam's soul was built to crave a life it could never be a part of. He decided that, yes, Sam was a tragic character.

He wished, for the thousandth time, that his Father's mysterious ways were at least fair.

He wished that he didn't have to see Sam Winchester changing, and hurting, and dying again – and being so calm and accepting about it. He wished he could fulfil Dean's prayers to keep his younger brother safe.

And, for the first time since Naomi had started forcing him to practise killing Dean over and over, he prayed: he prayed for the peace that Sam felt, even when forced into suffering against his will. But most of all, Castiel prayed that both of their painful, intractable situations could have a happy conclusion.

Castiel emerged from the dream, and before he left put his fingers to Sam's forehead, emptying his mind of the haunting subaqueous dream he'd witnessed. He filled it instead with uneventful memories of warm, lazy Sunday afternoons spent in the Impala, with Castiel sitting in the back, invisible and unnoticed, as the brothers squabbled over the music.

If you don't know the story of Orpheus and Eurydice, then I'd recommend it. It's quite a sad Greek myth, and this story is reminiscent of it.