Castiel stared at the Doctor for a long moment, lips parted in awe. A Time Lord. He'd never heard of such a thing, and part of him wanted to protest. He had been alive for millennia, he remembered the very birth of humankind itself, and angels had had the powers that this creature claimed. He wondered for a moment if this was something like what Dean had felt, when he found out angels were real. Castiel had never imagined such a creature, and yet here one stood in front of him... offering snacks. Preya was proving a more curious and whimsical place than he'd realized when he'd decided to hide away here. So many secrets to uncover...
Lydia's movement caught his eye, but he didn't turn until it registered what she'd said. Then he turned his intense gaze back to her, examining once more the aura she gave off. "Oh," he said, eyeing her, "That explains you." It didn't really, because she was not at all like the banshees he knew. She was far too close to human. Then again, he wasn't familiar with... whatever a Time Lord was either.
Suddenly caught by the wonder and irony of the situation, he let out a low bark of laughter - not exactly a charming sound, coming from him... more awkward and gravelly. The three of them had clearly all expected their companions to be human, and yet none of them were. "A Banshee, a Time Lord, and an Angel walk onto the beach..." he said, a big gummy smile still on his face. With that, he plopped down in the shallow surf with a splash, letting the water envelope him up to the chest and make the tail of his coat float up around him. "What a funny world."