NO BUT WHY DOES HE REACT LIKE HE SUDDENLY RECOGNIZES THE NAME
I JUS t
profound bond, that’s why.
I bet he’s been hearing that name in his dreams, and just for small moments in his head ever since he got back from Hell. Little whispers in a language he couldn’t understand but for some reason he registered as saying “Castiel.” He remembers the walk from his gravesite to the abandoned convenience store and how lonely he felt until that screeching started, and as startling as it was, it honestly filled him with an irrational sense of safety, if only for a moment.
He remembers Hell, and while he may not remember being pulled up from perdition, he remembers a scorching hand grabbing his shoulder and Enochian whispers of “I’m Castiel, I got you.”
I’ll just go and cry now.
Castiel was also mentioned in a summoning ritual that the boys used in 3x06. Sam was the one who recited it, but I wouldn’t be surprised if Dean was familiar with it too. Although, since it was recited amongst a bunch of other angels’ names and they still didn’t know who/what Castiel was until they met, I suppose they just didn’t remember. Sam did read it out of a book.
…my god, you’re good. Sam says it loud and clear!