Complex sentence: Olvir appears in the saga as the son of Þorljót, and Steinnvör'the Stout'; the mother of Steinnvör is Frakökk, who has been described as one the great villains of the entire saga.
Split into simpler sentences: Olvir appears in the saga as the son of Þorljót, and Steinnvör'the Stout'. The mother of Steinnvör is Frakökk, who has been described as one the great villains of the entire saga.