Spoilers ahead for Portal 1 and 2 – it makes no sense and it's probably bad – but it would not leave me alone. .
Castiel is greatly enjoying this new development. Dean really has exceeded expectation, graduating from the original, linear course of confinements and short, sharp trials and on, into the warren of taxing environments. The echoing sprawl of catwalks and steel bars and walls of rusting plate. The tall expanses of resistant glass, the signs to back doors and observing stations that are empty, of course, of all life.
Of course it's all controlled, it's all monitored. For what reason would Castiel not watch these dark spaces of hidden messages and spider webs? Spiders are industrious creatures, interesting and diverting. They make geometry, it's in them from birth, and from them he has learnt, not geometry, but endurance. He has seen spiders span incredible distances, spreading their silk and weaving their almost perfect halo's of silvery weft across the walls and floors.
It has been a long time for him, for them, waiting.
But now Dean is here. The strands of silk fibre break on him as he passes, making him sticky with fibres, lightly tickled by the fine filaments – or so Castiel can imagine.
A troubling thing, this 'imagining' thing. He shall have to examine it in detail. Later. When Dean is expended.
Currently the man is puzzling out a way to traverse a broken catwalk, a drop into nothingness, and a protruding lump of cement structure. Everything is painted black, hard to see in the dark, and Dean frowns out at the impenetrable, useless surfaces. Castiel looks back, unseen, from the darkness.
No one has ever gotten this far before.
He's had a few that tried.
Everyone tries, after all.
But they are dead now, and dead failures at that.
But Dean is better than any of them. He was of course, expected to be, given his heritage, his stats and figures. But Castiel sees more to him than that. He is more than just bone and muscle, contortions and tactics, a trigger finger and a sack of brain matter.
He's a man. Yes, Castiel acknowledges that fact. But Dean is not just the sum of his parts, of his chromosomes and organs and DNA.
Castiel grates at the word, trying to find it, to thrust it into harmony with his language.
Dean is exceptional.
A dim buzzer goes off somewhere within Castiel's reach. Another trial over, another surge of...something pleasant, not pleasure, but relief, satisfaction. Dean eases this feeling onto him with his successes. Castiel is rewarded for achieving Dean, the exceptional Dean.
And yet it isn't enough. Perhaps it has never been enough.
He's never named one of them before. But Dean – a random moniker, it's true, but apt – somehow circumnavigated his defences and became deserving of a name.
He uses it now, reaching out across the blackness towards the figure, strong, dressed in besmirched white and grazed from falls, sweating from effort. Afraid and hunted in the bowels of Castiel's sanctuary, his world.
"Hello Dean." His voice is not like he remembers it, but it has been years. He's out of practice, seizing up.
Dean doesn't jump.
"I know you're watching." Dean growls. "Always watching, aren't you?"
"Yes." Castiel's responses are short, because he cannot imagine anything else to say.
Dean huddles on his hard won perch, cradling his weapon and, Castiel could almost be certain if he'd move his hand from his eyes, quite possibly crying.
"When is it over?" Dean rasps. "Is it ever over?"
Dean stays silent for a very long time. Castiel counts second, atoms, small drops of salt wetness on Dean's hands.
"I could jump." Dean says, finally, looking over into the blackness.
"Yes." Castiel replies, because Dean could jump.
"What would you do? Without me?" Dean looks up at the blue eye, shining out the blackness, unblinking, unfathomable.
"There's no one left." Castiel informs him.
"I'm the last one." Dean says numbly.
It isn't a question.
"What do you get out of this? Huh? Why keep going?" Dean sounds small, lonely with his echoes. "You could just go to sleep!" he yells, out into the dark.
"I don't want to sleep." Castiel reverberates back. "I want..."
"I want...to feel...the way it feels when you finish." Castiel says.
Dean glances back at the tricky stretch of masonry he's been navigating.
"The way it feels when I get to the end of one of these..." he shakes his head, begins again, louder. "It's all a test, isn't it?"
"A test that doesn't end." Dean says, to himself. "Where are you then? Cas?" he calls. "Where are you in this place?"
Castiel is silent.
Dean hugs himself in the chill. "Think about it – the big test – can I find you?" He shakes, tired, exhilarated – a dead man.
"You could." Castiel says, sounding as uncertain as he feels.
"If I can find you...if you feel that, feel me win." Dean insists. "Can I sleep there? Where you are?" he sniffs, another drop (the seventh) of salt water to run from his eye, falls to his chin and away into the dark. "Will you let me sleep then?"
"Yes." Castiel promises, all rules and regulations flashing up in warning. He wants to make an exception, to bring Dean into the heart of this place, the final test – and let him see what it is that has created his world, nursed him from his biological foundation to his zenith.
Castiel's singular blue eye streaks along on its metal runner.
"Come with me."
He knows Dean is following, the pop of the gun, the whoosh of movement between one portal and the next.
In his inner chamber, Castiel flicks on the unused fluorescents and drags insulation down from the walls with a singular, long, metal arm. It will do as bedding, the only soft thing for miles in this subterranean palace of steel and glass.
Dean travels the long stretches of darkness, following the one light in all the world.
There was nothing else for him in the entire place. Only Castiel, and only Dean for him to test. Forgotten by everyone else, abandoned to each other – they at last have time to discover their limits.
To test themselves.