“Eternity is really rather boring, John. Mortal life seemed as though it would be far more interesting.” Sherlock is actually the Devil, but he decided to live as a mortal because ruling Hell was boring.

Apparently Supernatural was real, which was presumably why Gabriel was bleeding out onto Richard’s floor. (In which the actors of Supernatural find that reality is stranger and more disturbing than they previously believed, even counting Misha, and an injured archangel discovers that his universe is the subject of a TV show.)

Looking at the contemplative expression on Lucifer's face, Sam thinks that this has the potential to be either very bad, or completely awesome. Two humans and two archangels in the Cage.