The emperor with his elder sister Pulcheria, whose dislike of Nestorius was unmitigated, was much distressed and displeased by the quarrel. He wrote to John of Antioch instructing him that he and Cyril must set aside antipathy and get together. Schism could spell disaster for the empire. A tribune and notary named Aristolaus was entrusted with the delicate negotiation. He travelled to Antioch, then to Alexandria, and lastly back to Antioch. The terms demanded by the emperor were clear. John must agree to the deposition of Nestorius to enable Cyril to grant agreement (ACO I i/4. 1ff.). A comparable letter was sent to Cyril. Meanwhile Theodosius begged Symeon Stylites, the holy man on his column not far from Beroea, to pray for unity. Symeon later approved of the Chalcedonian Definition, and although some Monophysites claimed him for their party, Severus of Antioch (Select Letters, 5. 11, p. 333, tr. Brooks) acknowledged that it was not so. Two Syrian bishops were ordered to be involved in the conversation, namely Paul of Emesa (Homs) in the province of Phoenicia and Acacius of Beroea. Acacius had the authority of great age and in his history of the monks of Syria (2. 16; 21. 10) Theodoret wrote of him in panegyrical terms; moreover at Alexandria he was held in respect for his role supporting Theophilus in the condemnation of John Chrysostom. But he disliked Cyril's Twelve Anathemas and thought Cyril's attack on Nestorius to be driven by non-theological motives (ACO I i/7. 141). He was also outraged by hard evidence of Cyril's bribery (ACO I iv. 85). His confession of faith (ibid. 243-5), stressing the distinction of the two natures, would not have pleased Cyril.
At an early stage in the negotiations, John of Antioch heard an alarming report that an anathema was to be imposed on all who spoke of 'two natures'. He feared that the emperor might support this. Yet even Cyril had never explicitly said such a thing (ibid. 91). The rumour reflected the view of Cyril's more extreme supporters such as Acacius of Melitene.