_It is said that when Ragnarok comes, the serpent who spans the length and breadth of the world shall awaken from his oceanic slumber to poison all life, while his sibling the wolf devours night and day to plunge existence into a ceaseless din from which few will ever recover. Only the deaths of these beings, and those who follow them in the conflagration, are said to end Ragnarok to start the world anew..._

This is Starbo's brother, to fit nicely for her Fenris role. As for why he has arms and legs? So he can grip the world easier when the din does indeed happen.