Castiel watched curiously as Cole summoned more lightning, but said nothing. He allowed the other man to do as he needed to do in order to see what he was being shown. It was a useful ability and he idly wondered if perhaps there was some way they could combine abilities if a threat ever arose. It seemed the practical thing to do in any event.
"They are on a plane of existence independent from the one we are now. They only truly manifest when I exist as a multidimensional wavelength of celestial intent," Castiel explained bluntly. "However no one may look upon our true forms. Doing so...results in blindness."
While he had warned Pamela Barnes and had felt no conflict over his actions at the time, he'd had time to learn remorse. What had happened to her was truly unfortunate.
"Also it is twice the size of the building we are standing on now. It is why we cannot simply choose whatever vessel we please."