Long ago Loki god of fire had three children with a Giantess. These children were Hel the goddess of the underworld, Fenris wolf a wolf who's jaws stretched from heaven to hell, and the Midgard serpent. This serpent was so big it could wrap itself around the Earth.
At this point, fenris was small and resembled a puppy so the gods took him to Asgard in hopes of taming him. However this proved to be a fatal mistake...
Well lads it seems the wolf is too big we must chain him before he attacks asgard!
Thou shalt not bind me! I am Fenris wolf the bringer of Ragnarok!
The gods of Asgard tried to bind the wolf but he snapped the chain into two.