These brothers are said to be the sons of Boreas, the North Wind, and so they're sometimes called the Boreads. Being the sons of a wind, these heroes had the handy ability to fly. Sometimes they're depicted with wings, while other times the wind itself just picks them up and takes them where they want to go. Their flying skills prove useful when the Argonauts decide to free King Phineus from a nasty flock of Harpies. In some versions of the story, Zetes and Calais die while fighting the Harpies, when, exhausted from chasing the winged monsters, the brothers fall into the sea. In other versions, however, the Boreads make it through just fine and come zipping back to the Argo ready for more adventure.