Burning Ice, Bitting Flame, this is how life began.
The Norse God of mischief Loki and the Giantess Angroboda had three monstrous offspring. The eldest was the wolf Fenrir; the second was Jormungand, greatest of serpents; and the third was a daughter called Hel. Hel's looks were quite likely to single her out. Although most of her body was normal and attractive, from her hips down, every inch of Hel's skin looked decayed and greenish-black. Her expression was always the same: gloomy and
"Expect nothing from them but the worst," Skuld said. "Expect them to harm you and endanger you. They will be in at the kill."
And so the gods agreed that Loki's children must be captured. At Odin the Allfather, and god of the skies' request, a group of gods crossed by night into Jotunheim, the world of the giants. They burst into Angrboda's hall, gagging and binding her, they then kidnapped her children and carried them back to Asgard.
Odin was in no doubt as to what should be done with the serpent. He picked up Jormungand and hurled him into the ocean surrounding Midgard, the world of men. Jormungand hurtled through the air smashing through the iron face of the water. There he lived and there he grew.
Odin was just as sure what to do about the serpent's sister. He took one look at Hel and hurled her out of Asgard down into the mist and darkness of Niflheim, the world beneath the worlds. As she fell she heard Odin's decree that she should look after the dead, all those in the nine worlds who died of illness or old age.
Fenrir was dealt with as well, but that is it's own story.