“The Monster at the end of this book” (4×18)
This episode, first aired on April 2, 2009, begins with a quick shot of Chuck having a vision of the future before cutting to Sam and Dean at a comic shop investigating an apparent haunting. However, when they question the manager, he asks them if they are “LARPing” as Sam and Dean from the “underground cult” Supernatural books written by Carver Edlund.
Upon reading them, the brothers are surprised to find that the books accurately depict their lives leading up to Dean’s trip to Hell. In addition, they find that there is a robust online fan community with “Sam girls” and “Dean girls” and “slash fans,” the last of whom imagine the brothers in a romantic/sexual relationship with each other, which outwardly disgusts them.
After receiving his address from the publisher, the brothers walk up to Chuck’s door while, at the same time, we see Chuck reading his newest pages: “Do they really want to know the secrets that lay beyond that door? Sam and Dean traded soulful looks. Then, with determination, Dean pushed the doorbell with forceful…determination.”
When he answers the door, Chuck (mis)recognizes them as fans and tries to dismiss them, but they force their way in, insisting that they are not fans but characters, and he is writing books about their real lives. When they reintroduce themselves with their last names, he is finally convinced because he had never revealed those to anyone.
Throughout the rest of the episode, the brothers try to figure out how Chuck knows what he does (spoiler alert: he’s a prophet of the Lord) and avoid fulfilling the future Chuck has written.
The God Author 