Relations between Isaac and John II were cordial at first, but began to deteriorate, so that by 1130 they had become estranged. The reasons for this are left unexplained by the sources;
Niketas Choniates and
John Kinnamos simply report that Isaac had set his sight on the throne. Possibly the onset of the rift between the brothers was in 1122, when John raised his own firstborn son,
Alexios, to co-emperor, thus superseding Isaac. In 1130, Isaac became involved in a conspiracy against John at a time when the latter was away from
Constantinople, campaigning against the
Seljuk Turks of the
Sultanate of Rum. The conspiracy was uncovered, but Isaac and his two sons managed to flee Constantinople and find refuge at the court of the
Danishmendid emir
Ghazi () at
Melitene. Isaac remained in exile for six years, during which time he traversed most of
Asia Minor and the
Levant, seeking to create a broad alliance with other rulers, both Christian and Muslim, against his brother. The main sources for this period of his life are Choniates, the court poet
Theodore Prodromos, and the
Syriac patriarch and chronicler
Michael the Syrian. From Melitene, Isaac went to
Trebizond, whose governor,
Constantine Gabras, had broken away from Byzantium in 1126 and was ruling the area of
Chaldia as an independent prince. In the winter of 1130–1131, according to Michael the Syrian, Isaac met again with Gabras, and a league was created between Isaac, Ghazi and the Sultan of Rum,
Mesud I (). Isaac then went to
Armenian Cilicia to entice its lord,
Leo I, into the league. He was initially well received in Cilicia and spent some time there. His eldest son
John even married one of Leo's daughters, and received the cities of
Mopsuestia and
Adana as his new wife's dowry. After a short while, however, they fell out with Leo too, and were forced to seek shelter with Sultan Mesud, abandoning their possessions in Cilicia. According to Michael the Syrian, news of these machinations enraged John II, who in 1132 embarked on a campaign against both the Turks and the Armenians, capturing two fortresses on the shores of the
Black Sea. However, his campaign was cut short when Isaac's sympathizers in Constantinople tried to use the emperor's absence to stage a coup. Informed of the conspiracy, John returned to the capital and thwarted their plans, but the Turks were able to counterattack and raid successfully into Byzantine territory, threatening the fortresses of Zinin and Sozopolis. Following 1132, Isaac is no longer mentioned by Michael the Syrian. During this time, he visited the
Holy Land in pilgrimage, financing the construction of a new
aqueduct for the Monastery of
Saint John the Baptist near the
Jordan River. The historian Konstantinos Varzos considers it likely, although no source mentions this, that the journey also had the purpose of seeking the aid of the
King of Jerusalem,
Fulk (). ==Return to Byzantium and accession of Manuel I==