Whenever he was finally able to move on from the Cave, it was likely that Cas would begin looking for all the same things Mal had tried and failed to find as well. It didn't seem like there was anything of much use to be found anywhere at this point though, leaving Cas to learn about nothing more than normal human contraptions.

Castiel had watched the train come and stop with a certain sort of curiosity and slightly tilted head. It reminded him a bit of the one time he had taken a bus, but of course recognized it was a fundamentally different vehicle. In any case, his eyes were still on the train itself when the passenger spoke, though he was aware of the fact that she was speaking to him. "Yes." Cas replied after a brief pause, finally turning to face the woman. "I am looking for answers."

He admittedly was not yet ready to pretend to be a normal human being if only to appease the strange people running the place.