I was trying to wait until the end to comment, but the mythology of this is FASCINATING. Dean as a different sort of demon, the Angel of Hell he struck a deal with for revenge and to get himself back, the fact that the angels of Heaven started actually fighting to keep the Seals unbroken once Dean was out of reach. (What a brilliant explanation for those extra years.) The Rendering where Lucifer has managed to trap and warp human souls for millenia. Human souls with an affinity for Order or Chaos. Wow.

Also, Dean with the spell written on a piece of legal pad paper stuck in his pocket, and Sam insisting they put it in a rigid plastic protector really amused me.