The Norn spun the threads of fate, which controlled the fates of every living thing. Because of this, the gods feared them and had no control over them. The Norn would ultimately decide the fate of everything, and thus also controlled even Ragnarok, or the doom of the world, itself.
Yggdrasil was an eternal thing, as it was protected by the Three sisters themselves. It is said in Norse mythology that Yggdrasil will survive even Ragnarok, so it can preserve Lif and Lifthrasir, who will then repopulate the Earth.
In Norse mythology, Yggdrasil is the giant ash tree that encircles the entire Earth, thus giving it the nickname of the “World Tree”. Its roots travel to the nine planes of existence. From lowest to highest, they are Asgard, Vanaheim, Ljossalfheim, Svartalheim, Midgard, Muspellheim, Joutunheim, Niefelheim, and Helheim.
The Norn are the three sisters of fate, who each represent a state of time. The three sisters were Urd, the sister of the past, Verdandi, the sister of the present, and Skuld, the sister of the future. The Norn watered Yggdrasil every day from a magic well to keep it alive.
