I thought the opener was fantastic, but something that has me absolutely confused is the issue as to whether Eve (The Mother of All) or the Leviathan are more powerful and more important. It seemed to be made clear last season that Eve was the Queen of Purgatory and in charge of the place. But, if the Leviathan are as old as she if not older (which came first, the Leviathan or Eve?) why wouldn't they be in charge of Purgatory as opposed to her? I guess I'm just trying to understand the pecking order of Purgatory here.
The show will have to give some type of explanation of how Eve and all her monster creations fit in with the Leviathan though (hopefully a satisfactory one) as the Leviathan are going to have to be a more dangerous threat (as they seem to be) to Sam/Dean/Bobby than Eve was (and I think Eve was woefully underused personally).
Here's my vote that we get an introduction to Cthulhu making an appearance too! As an "Ancient One" perhaps Cthulhu is a Leviathan!
Well I think from Death's description, the Leviathan came before Eve. I guess I never thought she was ruling Purgatory, but more like the creator of monsters.
It is an interesting question that I'm not sure we'll get an answer to. I would guess though that since the Leviathans were strong enough to remain behind and also take over control of an angel (Cas) means they were stronger than Eve to begin with and most likely the ones in charge in Purgatory.
Of course it's just conjecture