Alduin is the Nordic variation of Akatosh, and only superficially resembles his counterpart in the Eight Divines. For example, Alduin's sobriquet, 'the world eater', comes from myths that depict him as the horrible, ravaging firestorm that destroyed the last world to begin this one. Nords therefore see the god of time as both creator and harbinger of the apocalypse. He is not the chief of the Nordic pantheon (in fact, that pantheon has no chief; see Shor) but its wellspring, albeit a grim and frightening one.
Another legend says that Alduin can "eat" away the age of his victims, and that he once ate the entire Nord population down to age six after being summoned by Orkey.