Demetrius Soter: Early Beginnings of the Seleucid-Antigonid οἰκειότης in Libanius, Or. 11 Angus Llewellyn Jacobson, University of Tasmania Seleukid Lecture Series 8.1 Abstract When Seleucus I and Demetrius I established their οἰκειότης (kinship) at Rhosus after the Battle of Ipsus (301), the nature of power in the Hellenistic world fundamentally transformed. For the next fourteen years, the consolidation and preservation of Seleucus and Demetrius’ dominions essentially rested on this οἰκειότης – an impressive result for a peace established on shared distrust for the other Successors. Or so the traditional narrative imparts. Libanius’ Antiochicus, however, offers unobserved insight into the origin, or consequences, of the οἰκειότης through its focus on Seleucus’ flight from Antigonus Monophthalmus (316). For Libanius relates that Demetrius was responsible for Seleucus’ salvation. This paper seeks to determine the veracity of Libanius’ account on Seleucus’ flight and understand the origins of the ‘Demetrius soter’ flight tradition. In order to achieve this, I compare Libanius’ account with the extant versions of Seleucus’ escape from Babylon, including that in the Babylonian cuneiform fragment BM 35920, and with the strikingly similar flight myth of Mithridates Ctistes in Plutarch’s Demetrius. Ultimately, while revealing the plausibility of early relations between these two Diadochi, the paper concludes that the Libanian Demetrius soter tradition likely precedes the Mithridatic version and thus could have developed out of the οἰκειότης and subsequent negotiations with Ptolemy. These conclusions prove significant as they add nuance to the understanding of early Seleucid-Antigonid relations and post-Ipsus politics, revealing the value of propagandising the alliance’s longstanding nature, and more significantly, suggesting that the reasoning behind Demetrius and Seleucus’ οἰκειότης was far more profound than just necessity.