Dean: "Hey Sammy, I found something!"

Sam was standing right by Dean's 1967 Chevrolet Impala talking to Castiel, An angel, while Dean was looking for a demon in an abandoned house, where he had found you.

Sam: "I'm coming!"

Sam runs over to Dean, and suddenly stops when he sees your unconscious body in Dean's arms.

Sam: "Who is that?"

Dean: "I don't know."

Castiel walked beside Sam to see who they were talking about.