What he'd witnessed was...strange. Cas had yet to see anything of a semi-metallic, yet organic nature, but then he imagined he would not have. This was likely yet another instance of him seeing what could not exist within the confines of his own reality. That meant having to accept it without question, which was difficult...but evidently, it was not the time to delve into the art of philosophy or science.
"Are you all right?" he asked, grabbing a second rabbit and slicing its head from its body. "If you are, I suggest we find shelter."
Primarily, he was trusting the other man not to be a foe. He could see no demon face or sense anything that might have suggested a supernatural being of malicious intent. Though seeing as humanity had a tendency to be equally as malicious on occasion, Cas wasn't certain what to think. Given the other man's size, he felt it was a battle he would be hard-pressed to win.
Dropping the rabbit carcass, he rounded on one of the ducks and stabbed it quickly. "Quickly."