Born in 1126 as the oldest child of the sebastokrator Andronikos Komnenos and his wife Irene, John became orphaned when his father died in 1142.
[2] John then came under the protection of his uncle, Emperor Manuel I Komnenos (r. 1143–1180),[3] to whom he remained close throughout his life: in his opulent palatial residence in Constantinople, John commissioned mosaics depicting the martial deeds of the emperors of the Komnenian dynasty, with an inscription that lauded Manuel as his "spiritual father" and even a "second God".
[5] In 1148 John took part in a tournament in the Western style held at Heraclea, where he was wounded and lost an eye to the lance strike of an Italian knight.
[9] While John with a part of the Byzantine garrison remained at the capital, Nicosia, the general Michael Branas led a force to confront the invaders.
The rape of the island lasted for three weeks, before Raynald and Thoros re-embarked their men upon the news of the approach of a Byzantine fleet.
[13] In 1158 John accompanied Manuel on his campaign in Cilicia; his presence is attested at the reception of King Baldwin III of Jerusalem at Mopsuestia.