Castiel looked up at the Doctor, a bit startled. "Yes. Spring tides. That's correct," he said. Not too many people bothered to actually engage with him about these kind of things. They were always trying to steer conversations back to apocalypses or battles or, when he was still in the hospital with Meg, medicines that he didn't need to take.
He blinked as a marshmallow appeared under his nose, this one browned and steaming, and turned to stare at Lydia with curiosity. He took the hot, sticky, gooey thing from her with his bare fingers and held it close to his face to smell the caramelizing sugars, the slightly burnt edges. He gave it a squeeze, letting the goo ooze between his fingers and make a mess of his hand. Hesitantly, he nibbled some of it off his finger. He got that same burst of various chemical compound flavors, this time with a stronger taste of carbon to it.
Taking another taste of the marshmallow, he looked back and forth between Lydia and the Doctor. "This is good. Sharing food is considered a bonding experience, correct?" he said with a pleased smile.