Fenrir was only a puppy, but he began to grow and it was impossible to control him, so the Aesir (the main gods of the Norse pantheon) decided to keep him in Asgard, to keep him guarded, but everyone was afraid to take care of him, so they decided to tie him. They brought the chain to Fenrir, who, knowing that it was made up of magical ingredients, refused to put it on. The Aesir promised that if he failed to break the chain, they would release him, but Fenrir, he refused, but allowed to put it on if any of the gods put a hand on his snout, as proof of good faith. Only Tyr, son of Odin, put his hand on the snout. Then Fenrir allowed himself to be chained, but seeing that he could not free himself, he closed his snout and took Tyr's hand.