 He was the only son of Count Dedo I, Count of Wettin ( – 1009) and his wife Thietburga, a daughter of Count Dietrich of Haldensleben, the first margrave of the Northern March.Theodoric thereby was a grandson of the Wettin progenitor Theodoric I.At Christmas 1009, after his father was killed in a fierce struggle with Margrave Werner of the Northern March, Theodoric was vested with the County of Wettin in the Saxon Hassegau (ruling as Theodoric II) by King Henry II of Germany at Pöhlde.