User blog comment:ImperiexSeed/The oldest being, archangel or leviathan?/@comment-101.160.191.17-20120522085708/@comment-5110811-20120525182849

Again, we don't know if leviathans have another form other than being serpentine black ooze. Only season 8 can tell, maybe. And you keep bringing up why archangels couldn't kill them, well it's because God didn't want to kill them. He never destroys his creations. He's God. He can do whatever he wants. And he choose for unknown reasons to lock them up. It's highly likely he didn't kill them or let his archangels kill them because being the Creator, he felt responsible for them becoming what they are. God knew it was his fault and didn't take it out on among one of his first creations. It's strongly implied that he is a benevolent, self conscious entity.

And again, Given their lack of exotic abilities like telekinesis and teleportation. I highly doubt the Leviathans can enter heaven. Or ever were in heaven to begin with since they are monsters. The vast majority of angels live in heaven in their true forms. Regarding Death's statement, he meant earth and the rest of the planets. Since we only know that the leviathans are puddles of black ooze and the angels are energy beings the size of skyscrapers, there's no way a leviathan can eat an angel in their true forms respectively. Argueing what a leviathan really looks like and it's size is pure make believe and speculation. An Angels true form is official canon. So let's not argue over whether a leviathan is the size of a mountain or a planet. That is pure hypothesis with no hint, proof, implication, or statement ever made in the show.