Bowed legs buckled, but held, and Castiel braced Dean until the sensation passed. The fact that he hadn't thrown himself backward and vomited was an improvement, and the angel made careful note for next time. If flight was their only option, that seemed to be the most manageable means for the hunter to endure it.
The look he received for the audacity of even asking for the keys to his beloved vehicle was expected. And endearing. Castiel's hand closed around the metal offering with a faint smile of his own. "I would be indifferent to this car if it wasn't yours." The Impala was a machine, doing what it was designed to do. It was Dean's love that made it Baby. A stake was claimed on the music, and Castiel did not argue, leaning back to watch the rear window as the tires reversed, and turned to find the dirt road they'd pulled off of. Not quite as smooth as pavement, but Dean didn't seem alarmed.
Black Sabbath was turned down low, almost too low to hear, and the Impala's heat was turned up. Castiel was well aware that the music being low imitated how sounds grew distant while falling asleep, and the warmth was added comfort to help lull him under. It'd worked before, several times, and would work again in the future. Never a guarantee, but the success rate was statistically significant. His brows raised a bit at the question, but blue eyes remained fixed to the winding road.
"No, I'm very aware of how it happened." The angel's voice was its usual graveled deadpan as the car slowed to a crawl around a deep dip in the road that Dean had minded on the drive in. "See, there this man. With green eyes I must have had a premonition of in my fledgeling years. Before Earth was even an idea. Because I chased that shade of green for eons, and then I found it." His head tilted at the irony, "In all places, Hell. And after this man's resurrection, he kept making this error. Repeatedly. I'm a divine construct of the Lord's will, and yet, he kept mistaking me for a person. To him, I wasn't a machine. I wasn't a celestial weapon. A cog in the divine plan, I was Cas."
Graveled tones softened the longer he spoke, until they barely carried above the sound of the engine and the radio. Above all else, he still wanted Dean to rest after that violent healing. "Then, when Lucifer was about to break free of his cage. That man looked at me with those green eyes. And begged me to do something. Cursed me when I wouldn't. Claimed I was already dead... In a way, he was right. Those watchful days with him felt like the most I'd ever lived. And there I was. Choosing the machine, because it was all I'd ever known." Castiel looked over toward Dean as he drove. "I rebelled for him. I was slaughtered for it, but. I was given a second chance. He calls that second chance the 'family mess,' but I call it freedom."