The Backbiter selects a target and then runs through multiple spaces to reach them, causing 2 Armor damage to each character he runs through. When the Dredge started invading, he tried to take control and used Ekkill as a puppet, presenting him as a madman.
He is the brother-in-law of Ekkill and murdered his own wife, claiming that she died of an illness. Some relation to Ekkill has seemingly driven this man away from Frostvellr, though he has never told you much about the exact reasons why. Onef is a Human Hero character encountered in the first part of The Banner Saga.