King George II of Abkhazia sent two of his younger sons, Theodosius and Bagrat, to Constantinople to be educated there, so that after his death there would be no dispute during his succession.
Theodosius first took refuge in the Kartli with certain Adarnase, then with David III of Tao where he remained for a while, and finally moved at the court of Kvirke II of Kakheti.
Demetrius III managed to convince Theodosius to organize a reconciliation, who agreed to return to Abkhazia with guarantees of personal security confirmed by oaths before the Catholicos and the clergy.
During the short reign of King Theodosius III, the kingdom became engulfed into complete chaos and feudal anarchy combined with the raids by the Kakhetians in Kartli, where the royal power had completely collapsed and a governor, Ioanne Marushis-dze, allied with the Georgian Bagratid prince David III Kuropalates of Tao to install Theodosius's nephew (sister's son) Bagrat as a ruler of Kartli in 975.
In 978, through Marushidze's efforts, Gurandukht's weak reigning brother Theodosius III was deposed and Bagrat, now of age, proclaimed King of Abkhazia.