User blog comment:ImperiexSeed/The oldest being, archangel or leviathan?/@comment-26106956-20150423005037

I believe the Leviathan are older, just because Death said so. I know that Supernatural was intended to end with season 5 so all of the statements on how Archangels are ultimate can be simply a statement that was exagerrated. And Since the leviathan were potentually locked away before angels were created, it is very possible that nothing outside of God and Death had knowledge about them. So everyone's statement on how the archangels were heaven fiercest weapon, don't remember exactly how Castiel put it, was acurate to everyone else given that knowledge. And Castiel did say that God said not to open the door to purgatory, so all angels being good boys and girls listened and never went to purgatory. later when monster souls were going to purgatory, they could have been like ooh so thats why god made it, or maybe the knowledge of purgatory existing before angels might not have been common knowledge at all.