The tale of Fenrir must start with his father, Loki. Loki was one of the most important gods of the old Norse tradition, seldom (if ever) worshiped by mortals, yet at the center of much of their mythology.

Loki was the son of the giants Fárbauti and Laufey, and blood-brother to Odin, the ruler of the Æsir gods. Little is known of Loki's first wife, Angrboda, other than that she was a giantess, and the result of their union produced monsters. In addition to Fenrir, Loki and Angrboda sired Jormungand a great serpent and Hel, a goddess that was half living and half dead with her body reflecting that condition.

When Odin heard of Loki's children he sent for them to be brought to Asgard, the home of the Æsir gods. Each of the children of Loki and Angrboda was predestined to play an important role in Ragnarok, the great battle that would herald the end of this cycle and the beginning of the next, and Odin was aware of this. Still he could not just slay the children outright to prevent the prophecy from coming to pass, as Loki was his blood-brother.

Therefore, Odin seized Jormungand and cast it into the sea, where it would grow and grow eventually become the serpent that surrounded Midgard, the world of mortals, clutching its own tail in its mouth. Odin the All-Father treated Hel more honorably, sending her to live in the underworld of Niffleheim, but at the same time giving her charge over the shades of those that died of disease or old age, and thus were unworthy of spending eternity in the glorious hall of Valhalla. Fenrir, the wolf, Odin decided to keep in Asgard, where the gods could keep watch over him.

Fenrir was small when he was brought to Asgard, a normal young wolf pup, but as he aged the gods saw to their horror that he did not stop growing when he reached the size of a normal wolf. Fenrir grew larger than a normal wolf, and kept growing, until he grew larger than the gods themselves.

While growing in Asgard, Fenrir found time to father two children of his own. Wolves like himself the children, Sköll and Háti, also grew to huge size and were destined, at the end of time to swallow the sun and the moon, bringing darkness to the world.

With each passing day Fenrir would grow larger, and this sewed fear among the Æsir. This fear grew, as all fear does, along with Fenrir’s size until only the bravest of gods, Tyr, would dare to feed Fenrir. At length, when he had grown so large that the Æsir felt unable to control him, Odin decided that the gods would need to find a way to chain Fenrir to keep him from spreading terror and destruction amongst gods and mortals alike.

The gods created a great fetter, called Leyding, of iron and brought it to Fenrir. They told him it was a game to test his strength, and after examining the fetter Fenrir allowed himself to be bound, judging the chains strength to be less than his own. As soon as the fetter was secure Fenrir flexed his mighty muscles and Leyding broke. The Æsir cheered and clapped, keeping up the ruse of the game, but inside they were even more terrified of Fenrir.

The gods went away and crafted an even more sturdy fetter, Dromi, which was twice as thick as Leyding had been. Fenrir examined Dromi, and he judged it to be twice as strong as the first chain, but his own size and strength had increased since the first contest as well, and he knew that he could still burst it.Fenrir allowed the gods to bind him with Dromi.

Fenrir flexed and twisted, and Dromi burst asunder. In despair, because the Æsir judged Dromi to be the strongest bond they could make, the gods turned to outside help.

The Æsir sent messengers to the dwarves of Niðavellir, asking them to make an unbreakable binding. The dwarves had made the living golden hair that adorned the goddess Siff's head, Mjolnir, the hammer of Thor, Odin's spear, Gungnir, and many other wondrous objects, and the Æsir thought if anybody could make an binding that Fenrir could not break it would be them.

The dwarves accepted the challenge and created Gleipnir. This binding was as light as a ribbon of silk, but far stronger than the strongest iron and made from such ingredients as the sound of a cat's footfall, the beard of a woman, the roots of a mountain, the breath of a fish, the sinew of a bear, and the spittle of a bird. This is why these things do not exist today.

When the binding had been finished and delivered the Æsir took Gleipnir and Fenrir to the island of Lyngvi and asked him to play the game again.

Fenrir looked at the ribbon-like binding the gods had brought, so different than the massive fetters Leyding and Domi, and suspected a trick. He refused to be bound with Gleipnir, but when pressed on the matter Fenrir relented on the condition that one of the Æsir place a hand in his mouth. None of the gods were willing to do this until brave Tyr agreed, knowing well that it would mean the loss of his hand when Fenrir discovered the trick.

Fenrir struggled as hard as he could and could not break Gleipnir, and when it became apparent that the Æsir would not release him from the binding he bit Tyr's hand off at the wrist. The more Fenrir struggles the tighter Gleipnir constricted him, he began to try to bite the other gods snapping his jaws in rage at all that came near. Finally when Fenrir opened his mouth wide the gods stuck a sword inside of it, up right with its tip at the top of Fenrir's mouth and its pommel on his tongue, to hold his mouth open.

The Æsir attached Gleipner to a great rock, which they then secured far underground. The bubbling drool that flowed out of his open mouth formed the River Van, and his struggles against the unbreakable binding were said to be the cause of earthquakes. There the Æsir left Fenrir, hoping that he'd stay bound until the end of time.

Fenrir lay bound for a long time, but not even the machinations of the gods can stave off the inevitable. At long last the signs began indicate that the time of Ragnarok was fast approaching. There was a long winter that lasted three years without a summer coming.

The giants were growing more and more restless.
The dead of Hel's realm were marshaling into an army.

Loki, the father of Fenrir and Hel, had been bound by the gods as well for the mischief that he had made, and in the fullness of time both Loki and Fenrir slipped loose of the bonds holding them. The time had come for the final battle that would end an age and usher in the next.

The Æsir, along with the worthy dead of Valhalla, called the Einherjar, gathered for battle on the plains of Vigrid. There they faced off against Loki, Fenrir, Jormungand, the giants of both Jotenheim and Muspelheim, and the army of the unworthy dead. Fenrir by now had grown so large that when he walked with his mouth open his lower jaw scrapped the earth while his upper touched the sky. The carnage was great on both sides, with few surviving the battle.

Thor slew Jormungand but was overcome by the poisonous fumes of the great serpent's breath and died soon after. Loki and Heimdall, the watchman of the Rainbow Bridge, likewise killed each other in battle.

Fenrir would get his revenge of the Æsir for binding him, for during the battle he fought Odin, the chief of the Æsir, and the god that had given the order to bind him. Their battle was over quickly, for Fenrir swallowed Odin, horse and all in one gigantic bite.

Fenrir's victory was short lived, however. After slaying Odin, and possibly Tyr, Fenrir himself was slain by Odin's son Vidar. The tales say that Vidar stood on Fenrir's lower jaw with a magical boot that could not be lifted but by the wearer, and grasping Fenrir's upper jaw in his hands he stretched it up until the great wolf's head burst.

The end seemed very near, Sköll and Háti swallowed the sun and moon, plunging the world into darkness lit only by the many fires that had been started by the flaming sword of Surtr, the king of the fire giants, who had slain and been slain by the god Freyr. There was a great rumbling as the world trembled and slipped beneath the sea.

There was silence for a time, but this was not the end. The sea parted and the land rose once again. The forests that had been burned were restored and teemed with wildlife. Baldur returned from the underworld and walked amongst the ruins of Asgard where he found Vidar, along with Magni and Modi, the sons of Thor and a few other gods and goddesses still living. In Midgard, two humans awoke in the new world. Lif and Lifthrasir were their names, and they would go on to repopulate the world with men. And the cycle began anew.