User blog comment:Fusedtwilight/Possible Season 11 Plots/@comment-3045936-20150522044239

My idea is this. The darkness covers over a great distance before Sam, Dean, and the Impala are saved most likely by God. But that several months to a year passes due to being surround by the Darkness, even though it might feel like seconds to them. The darkness dissipates as it needs to gather strength to destroy creation for being sealed for nearly countless years. That in order to do this it infects humans with it, so they can do great evils to create more evil darkness in the world. I think that they will need to destroy the heart of the darkness, which could be in a physical form. It won't kill the darkness completely but will weaken it to the point that it can be sealed away with a new Mark or spell.