So this was a mix of a couple things, mostly the quote “My true form is approximately the size of your Chrysler Building.” And an idea that I think was from His Dark Materials about Angels looking like architecture. So, Chrysler!Cas I guess?
Cas shimmies free of Jimmy’s body, and in a burst of light and song he expands—no, he unfurls, that’s the only way to describe this, this construction. Cas’s skin snaps. His bones become t-bars. Fabric hardens into steel. And the flesh, once so scarred and bruised, arches and stretches and buttresses itself, and it soars up, and up, and up.
From somewhere near the moon, two bright, blue lanterns blaze to life. Their brilliance, warm and inescapable, fixes on Dean, and suddenly he feels roughly the size of an ant.
“Dude,” he mutters, swallowing back a gasp. “You’re a Transformer.”
“I am an angel, Dean,” comes the impossible voice, the sound of it like steel scraping against cement, or towers crashing to the ground. Dean no longer wonders where the gravel in Cas’s human voice came from. “I am incapable of transferring electrical energy.”
“What? No, a Transformer—nevermind.” Dean shudders. “So. That’s what you really look like?”
The creature nods—or, rather, the top part of it sways precariously, metal screeching as it does.
“I apologize. My true form—“ Cas blinks, and the light goes out; Dean is surprised at how quickly the chill returns to his bones, “—can be overwhelming to lesser creatures.”
“Yeah, whatever.” Dean tugs his coat around him tighter, and tries not to think about how weird all of this is; that this—building—once scarfed down cheeseburgers and killed demons and got him kicked out of a strip club. “Just don’t step on me.”
Near the top, the travertine and steel rearranges itself into an inverted arch. “I’ll try.”
Next to him, Cas tromps along, his massive legs leaving pits in the Purgatory dirt. The holes remind Dean of the foundations of houses, like the ones he used to build in his year with Lisa, and they make him angry for some reason, as well as sad. “Can’t you be any quieter?”
“It is difficult to control my true form in this dimension,” admits Cas, no small amount of frustration creeping into his voice. “If I could maintain my vessel here, I would.”
Dean peers up at Cas. “But doesn’t being all Iron Giant make you feel powerful?”
“No. I feel—“ Cas pauses, his metal skirts settling around him until he looks like those old ziggurats, except without all the dirt and jungle clinging to his skin. “Small.”
Dean laughs—until he realizes Cas isn’t joining in.
“Cas, c’mon, you for real?” Dean squints up at the blue lanterns, heat rising to his cheeks. “How can the Chrysler Building feel small?”
“Because, Dean,” says Cas, and the metallic voice sounds so far away, “I can see further than you do.”
They pause for the night. Cas offers to keep watch, which seems like the smart plan—but then, goddammit, the bastard keeps training those megawatt lighthouse-eyes right down on Dean, right as he’s about to fall asleep, and the heat and luminescence snaps him back to full consciousness within seconds.
“Cas,” he groans into his jacket, after the fourth time he’s been reawakened. “Turn down your damn headlamps already.”
“Sorry,” murmurs the stone. “I forget.”
Dean grumbles wordlessly into his jacket, still warm from his body heat, and he tries not to remember pressing his nose just like this into another coat, one that smelled like blood and lake water and car trunk, without a single trace of its former wearer left.
The blue light bleeds through the seams of the fabric once more.
“Dude.” Dean rips the jacket away from his head.
“Sorry,” replies Cas immediately, but the light doesn’t move, and the angel just sounds so sad that Dean can’t help but squint up into the brilliance. But he can’t make out anything, just light, everywhere light.
“What is it?”
“You said that already.”
“No, I mean—“ Cas swallows, and the noise is almost like an attic settling. “I—I once called you a brave little ant. That was rude of me.”
“Well, turns out that next to you, I am an ant,” chuckles Dean mirthlessly.
“You’ve never been small to me,” says Cas.
Dean clears his throat and rolls onto his side, facing into the light. He folds his arms across his chest, even though he’s not cold, not with Cas’s gaze on him. His hand settles on his shoulder, right where once blazed a handprint scar. Force of habit, he supposes.
“Y’know,” Dean says muzzily, pretending more fatigue than he really feels. “They say the eyes are the windows to the soul. I never thought they meant it literally.”
“You know I possess no soul,” says Cas, and he sounds even sadder than before, if that were even possible—if it were even possible for a tower to emote at all.
“I didn’t mean it literally either, Megatron.” Dean idly rubs a thumb along his shoulder and, despite himself, he remembers the smell of lake water. “I gotta say, though. I hope we get out of here soon. It sure is weird talking to a skyscraper.”
As if this—this—whatever this is between us—wasn’t strange enough, Dean adds in his head.
“Well, Dean, just think how it strange it is for the skyscraper.”
Something in the tone of Cas’s voice makes Dean wonder if the angel can still read minds in this form. But before Dean can ask, the light slides slowly, inexorably, away.