The chasm opens up out of the fog as if from nowhere. Dean can't make out an end to it in either direction, or a way across. He turns to Cas.

"We could try to find a way around?"

The angel shakes his head. "I'd rather not stray off course."

Dean nods. That would make this one of those important occasions that Cas has been saving his waning powers for. "Okay, then."

By the time Dean has braced himself, he and Cas are already across. Cas wobbles on his feet.

"You okay, man?" Dean asks.

"My first impulse is to lie and say, 'yes,'" Castiel answers. "But in the interest of honesty and communication: no." He sways and blinks. "Just give me a minute."

Dean watches his friend nervously, reaches to take him by the arm. "Let's just step away from the ledge, okay?"

Cas lets himself be led towards the tree-line. "I don't like to make you worry."

Dean considers telling Cas that his distracted rambling makes him worry, but decides against it. Instead he says, "We're stuck in Purgatory. 'Worried' is pretty much my default setting."

Cas gives him a lop-sided smile. "Touche."

It's then that Dean notices nearly a dozen sets of glowing eyes staring out at them from the trees.

Dean draws the angel blade just as a beast comes flying at him, and slashes it's throat. The fighting falls into a familiar rhythm, no thought, just instinct. Cutting, stabbing, surviving.

In his periphery, Dean keeps track of Castiel's position. The angel isn't zapping all over the place, but periodic flashes of light tell Dean that Cas is holding his own. Dean is also aware that the monsters are pushing them towards the chasm. He pushes back.

Dean thinks he's killed (as much as the things can be killed) the last monster and turns to see how Cas is doing, when a creature barrels into him, claws digging into his chest, pinning him to the ground. It takes all of Dean's strength to hold the thing's gnashing teeth away from his face.

"Cas! A little help here!"

Dean fumbles with the angel blade with one hand, while bracing his other arm against the thing's throat. He clumsily drives the blade through the thing's chest, and it dissolves.

Dean lies still for a moment, catching his breath. He sits up. He's alone.

"Cas?" Dean calls out as he gets to his feet. No answer.

A sick feeling settles in Dean's gut as he makes his way to the chasm, and looks over the edge. He can't see the bottom. He keeps looking anyways, as if by staring he can intimidate the darkness into revealing its secrets. And for a second, the walls of the cavern are illuminated. By the kind of light that would come from an angel smiting a monster. Or from something else happening to an angel.

"Cas!"

No answer.

Dean's instincts tell him that he should keep moving. We need to head towards the centre, Cas had said. We'll find the gate there.

He looks over his shoulder towards the woods. They seem darker than before.

He sits down to wait for Cas.

It's been several hours, and the sky is starting to darken.

It's getting harder and harder for Dean to ignore the part of his brain that's telling him, Cas could be dead. What then? You need to figure out how you're going to get to the gate. You need to deal with this.

"No. No, I don't have to deal, because Cas is coming back."

Dean realizes he's talking to himself.

So maybe Cas fell off that ledge. That doesn't mean he's not fine. He just needs some time to recharge, and then he'll zap back here.

Dean doesn't think about what would have happened had he gotten stuck in Purgatory by himself. He doesn't think about getting up and making his way through those woods alone. Or about the exhaustion, or the cold, or the loneliness. He doesn't.

Dean draws the angel blade across his palm, drips some symbols onto the ground around him. He doesn't know if the wards will work as well with human blood as with angel blood. But this is as good a time as any to find out.

Dean stays up all night. By the time what passes for a sun rises, blood red in the sky, Dean isn't trying to fool himself anymore. Okay. So I'm alone.

He takes a breath. He doesn't cry.

You need to get up, Dean. You need to keep going. Sam's waiting for you.

And Dean is about to get up, he is. He plants his hands on either side of him to push himself off the ground, but his muscles ache in protest. He's tired. Not just from the past night, but from everything. He's tired, and he's lonely.

Dean stays where he is.

Dean wakes up several hours later.

He figures it won't hurt if he waits a little while longer.

Castiel wakes up in darkness, lying on cold stone.

His senses are sharp enough that he can still see his surroundings. He looks around and realizes that he's at the bottom of a narrow chasm, walls of stone pressing in on him, a sliver of light far above. He also sees the silhouettes of wings seared into the ground on either side of him, confirming what he already suspected. Castiel has woken from death enough times now to recognize the feeling.

Castiel knows that the monster souls can't die in Purgatory, so maybe the same is true of him? But Castiel is neither a soul nor a monster. Perhaps his Father intervened again, though Purgatory is not His realm.

He's alive, at any rate. He supposes it doesn't matter how.

Castiel feels a tug at the core of his being. Something that says to him without words, Come back to me, or maybe, Come home. It makes him feel like he's missing a piece of himself.

He turns his gaze upwards, and spreads his wings.

Dean hears the rustle of wings, and is on his feet and turning towards the sound even before it's followed by a familiar, "Hello Dean."

Cas is there, and he might be missing the suit and tie, he might be different now, but this hasn't changed: he comes back. He's still Cas, and he came back.

"Ha!" Dean exclaims, equal parts triumph and relief, and is about to follow it up with an "I told you so," but then he realizes that he'd be talking to himself again, and that's a little weird. Instead he exhales something between a chuckle and a sigh, and beams at his friend.

"Dude, you have got to stop doing that."

"My apologies," Cas says with a fond smile. "I hope I didn't keep you waiting."

"Nah," Dean says with a wave of his hand. "Come on, let's go."