Unavoidable delay of squee, sorry. *smacks work* Here is a small point of pondering in the meantime:
Spoilers for 4.18
If the book series in show is to be a far-future Gospel of the Winchesters, does that mean the fanfic its fans are writing will be the Apocrypha of Sam and Dean?
And by extension, since all original material in any fandom is referred to as 'Canon' does that make then all fan works 'apocryphal'?
Oh, and because if I don't type it, I'm going to start shouting it in my very religious workplace and net myself a spurious amateur exorcism:
"I AM THE PROPHET CHUCK!!!" \o/
As usual, I'm staying almost entirely offline 'til I get my brain together enough after work for a full reaction post, (possibly late tonight), so I will catch up with you all after that.