Castiel tilted his head, staring at the white porcelain fixture with a puzzled look. "Its shape and function aren't intuitive. Why do humans design containers for cleaning water and waste so similarly?"
"This..." Dean was at a loss for words. "...Because that's just how it's designed. Listen, this is the flush button. Remember to press it when you're done."
"Castiel, watch the traffic lights! The direction indicated by the green arrow is clear to go! You nearly got hit by a truck just now!" Sam, his heart leaping into his throat, dragged the angel—who had been standing in the middle of the street with no reaction to the speeding vehicles—back onto the sidewalk.
Castiel watched the endless stream of cars and the flashing signals, seemingly trying hard to comprehend the system:
"These metal constructs move according to simple light-signal rules, but their speed and capacity to damage flesh do not match the simplicity of those rules. It is inefficient and dangerous."
Sam rubbed his forehead. "They're traffic rules! They're for safety! Please, just follow them!"
"You need to take off your clothes before bathing, Castiel. I only brought one spare change of clothes—here, take this!" Dean felt a headache coming on as he watched Castiel, fully dressed, walk straight into the bathroom and step into the bathtub to bathe.
He and Sam had not brought much clothing with them when they left.
"Human methods of cleaning are overly cumbersome and waste water. Heaven has no such need," Castiel stated, though he still began awkwardly trying to undo the buttons of his trench coat.
Similar scenes played out again and again.
The brothers had no choice but to patiently explain the most basic rules and common sense of human society to Castiel, as though teaching an alien from another world.
If