Castiel blanched when Dean mispronounced the word for "monster."

"Dean, that doesn't mean 'monster,'" he said, leaning in and whispering unnecessarily.

"Wha' does it mean, then?"

Castiel gulped, eyes widening and making his stare, if possible, even more intense. Dean mentally compared them to pits of blue fire. Or searchlights, because inadvertently or not, they always made him feel exposed. "It means 'harlot.' A-Babalond and A- Bai-ebond may sound similar, but they mean very different things."

Dean looked at him doubtfully. "You sure the meanings are so different? With your experiences with women…" His smile curved around the words, drawing them out and stretching them into an insinuating tone. He was remembering the brothel, one of his fondest memories of his adventures with Castiel when he and Sam had briefly broken up. Fondest mostly because he could hold it over the angel's head.

Castiel's eyes could communicate volumes, but they only conveyed a single word at that moment. Meg, they seemed to suggest, and wasn't that a whole lot of crap Dean didn't want to get into right then. He broke off eye contact, feeling as he did so a slight stinging pain in his gut. He didn't used to feel like he had to skirt around topics. He and Castiel could have entire conversations without speaking, and sometimes, without even seeing each other. Not anymore, apparently. Something fundamental in their bond was damaged, and Dean wasn't sure if it could even, ever, be fixed.

Look, Professor, I think that's enough for one day," he mumbled, looking at his shoes in the dim lighting of the cave with interest. What'll I do when they wear out? Skin a monster and tan its hide? "I know the words for monster, friend, and danger already. That should cover most of the course material, yeah?"

Not really, Castiel thought, but he didn't rebuke the hunter. Instead he looked intently at the man, taking into account his tired slump, the developing bags under his eyes, and the small twitch of the index finger on his left hand. He was fatigued. Castiel sometimes had difficulty following Dean's erratic sleeping patterns, but he knew that Dean's survival, at least in their situation, would be entirely dependent on how alert he was.

"You need to rest," Castiel pointed out helpfully.

"I know, yeah. But how can I, in this place? It's like we're stuck in Left 4 Dead in a safe room without any equipment!"

This earned him another blank stare, to which Dean inwardly groaned. "I'd just rather not sleep now." He didn't say that he was hoping against hope that this was all just a really screwed up dream. He didn't say that he knew sleeping would verify the reality of the matter, and he didn't say that he was afraid something would find them while he was sleeping and kill him and Castiel both. But he got this odd feeling that Castiel knew all that, even without him saying it. And that he didn't think him any weaker for it.

"Regardless," Castiel sighed, "I can keep watch." As he moved towards the entrance of the cave, Dean called out.

"Hey, Cas." Castiel paused and turned, facing him, but Dean's face was cast in shadow, so he couldn't see his expression. His posture was careless, but his hands were twisting in his lap.

"Yes, Dean."

"I'm glad you're here with me." And with this gruff pronouncement, Dean shirked his jacket, stuffing it into a makeshift pillow before throwing himself on his side, in a facsimile of sleep.

It was dark, so Castiel allowed himself to smile briefly, before pivoting on his heel and returning to the entrance of the cave. And I'm glad you're here with me, he replied silently, so although Dean's ears strained for a reply, all he could hear was the soft scrape of loose stones on the cave floor being dislodged by Castiel's sneakers. So, releasing a breath he didn't even know he was holding, he pursed his lips and squeezed his eyes shut, waiting for sleep to settle upon him.

Summoning the King of Hell was too risky an operation for Sam at the present moment. He had nothing, literally nothing that the former crossroads demon wanted, and nothing to threaten him with, either. Although Sam briefly considered just holding him with a Devil's trap until he got angry enough to tell him what he needed to know, prior experience told him that the probability he would escape and proceed to murder him was far too great to try it.

So instead, he threw himself into research. With Bobby gone for good, finding what he needed to know from books became much more difficult, but fortunately Sam was Internet-savvy and ran into quite a few tidbits online. While his investigation into prophets revealed zilch, he did find an interesting amount of information on Purgatory. Apparently, there were several ways of opening doors into it, but those were one-way doors, letting you in, not out. And as for the doors that did let things out, there was no way of controlling where in Purgatory the door would open up, or what exactly would come through the door when it was opened.

But one night, holed up in a rancid-smelling motel with his eyes nearly bleeding from exhaustion, he made a breakthrough. Excited, he half-turned in his seat to the empty bed on the right- hand side of the room, before remembering himself and abruptly turning back to his laptop monitor, blinking rapidly.

"It's not Cato, it's the boatman. If not the Boatman, then the Griffon. And it's ascension…" he whispered, stifling a yawn. "How do I summon…" But he was too tired to complete his thought. The fantastic amounts of caffeine he'd imbibed drained out of him in an instant, leaving him snoring lightly on the keyboard of his new laptop. It followed suit a moment after.

Sam didn't know it, but the exact moment he dropped off, Dean was jerked awake by a sudden commotion.