This is a symbol of freedom, rebelliousness, and ferocity.
Despite his role as Odin’s killer and bringer of Ragnarök, Fenrir isn't viewed as strictly evil in Norse culture. He, as well as his sibling Jörmungandr, is considered inevitable and a part of the natural order of the cycle of life.
Ragnarök isn't just the end of the world either, but an end of a cycle, after which history would repeat itself again and again.