Cas landed neatly, taking a moment to take in Lydia before turning his attention to Sam. His smile was almost too small to see but there was a flicker of warmth in his features as he said, "It's good to see you too, Sam." The light faded as quickly as it arose however. He was back to being all business.
He didn't like that Dean was missing and he didn't like that Sam was suffering something he didn't understand. Now he was in the presence of Lydia he could see Sam wasn't the only one. They were a curious collection indeed.
"Lydia is an ally," Castiel said with a small nod towards the girl. "We have discussed much." Cas didn't care about his living quarters but he liked the fact he'd been invited into Sam's. They had a base to work from now and that was useful.
He studied Sam, paying great attention to his head as if he could see the cause of his problem with his eyes but, special as they were, they told him nothing. "I think we need to talk," he began. "I presume you have heard Lydia's story, Sam. What do you make of it?"