The myth, as it's usually told
Fenrir, a son of Loki, grew so fast that the gods feared him. They tricked him into being bound with Gleipnir, a fetter made from impossible things, and only Tyr was brave enough to put his hand in the wolf's mouth as a pledge of good faith. When Fenrir realized the trick, he bit it off. Bound until Ragnarök, he howls, and the drool from his jaws forms a river called Ván: Hope.
What the song hears
They raised him to be the monster. The prophecy came true because they believed it.
