At the dawn of time, Odin and his two brothers killed the giant Ymir and created the world from his body. As usual, a god’s motivations are difficult to determine. Did Odin simply need Ymir dead for the sake of creation? Or did the Alfather reason that if Ymir continued to spawn giants that any order in the universe would become impossible? In any case, as the three gods tore the massive giant to pieces, a vast deluge of blood burst forth. This blood became all the world’s oceans, and the torrent swept away every giant – except for one family who escaped in a wooden ark. This giant was named Bergelmir, and all the later giants were descended from him.
Odin and his brothers made the land from Ymir’s corpse, with his teeth and broken bones forming the stones and the mountains, the great dome of his skull forming the sky, and even his thoughts forming the clouds – thin and wispy or dark and brooding. They called this world Midgard, and they encircled it with a mighty barrier made from Ymir’s eyelashes. They also made their own realm, Asgard. Asgard and Midgard (along with several other of the Nine Worlds) became “innangard,” a place of protection where the gods ruled. Beyond, were places the giants ruled – Jotunheim, Hel, and the other realms that formed “utangard” or, as both Utgard and utangard would be translated, “beyond the enclosure.”
Cast out into the darkness of Utgard, the Jötnar remembered a time when they ruled. Either out of a need for revenge or because – as the Eddic Poem says – they really were “born of venom and thus fierce and cruel,” the giants dream of a time when they will overcome Asgard and Midgard.
The time for them to unite and march against the gods will come in Ragnarok. In the meantime, many giants try their luck raiding the territory of the gods. The bravest of them sometimes appear in Asgard, with a challenge or a trick for the Aesir gods, or they come to terrify us mortals in Midgard. When the Vikings and other Nordic/Germanic peoples took shelter from howling storms, they knew it was Odin leading the gods in “the Wild Hunt” against the giants. When they saw thunder’s flash and the pound of lightning, they knew Thor was smiting giants with his mighty hammer, Mjolnir.
Sometimes, the gods and giants live in an uneasy peace. Not only did gods and giants often form marriages, liaisons, and alliances, but there were times when giants were even able to show some sympathy with the gods. For example, when the most beloved god, Baldr, died because of Loki’s treachery, even the giants wept. Peace never lasted long, though. Whether because giants would make incursions into Asgard, or because Odin or Thor would venture into Jotunheim on their adventures, the hostility between giants and gods was always kept alive.
This enmity and ages-long struggle will come to fruition at Ragnarok. There the gods and giants will destroy each other. Like the opposing forces of creation and chaos they seem to be, they will cancel each other out, and oblivion will resume before the universe is – perhaps – born anew.
Source: Sons of Vikings