John was born probably circa 1074, the eldest son of Alexios"s elder brother, the sebastokrator Isaac Komnenos, and his Georgian wife, Irene "of Alania". In 1081, his uncle, Emperor Alexios I Komnenos, proposed a marriage match between John and a German princess to the Holy Roman Emperor Henry IV (r 1056–1105), but nothing came of this.
In early 1091, John was chosen by Alexios to replace John Doukas as the governor (doux) of Dyrrhachium, in modern-day Albania. The city was of great importance to the Byzantine Empire, as the "key of Albania" and the main point of entry from Italy into the Balkans, a fact illustrated by the role it played in the Norman invasion in the early years of Alexios"s reign. Soon after the assumption of his duties, however, he was accused by Theophylact of Bulgaria of plotting against the Byzantine emperor.
Eventually, Alexios dismissed the allegations and reconfirmed John in his post.
Later, in 1094, despite his military inexperience, John was charged with confronting raids by the Serbs under Vukan of Rascia into the Byzantine province. John allowed himself to become involved in prolonged negotiations with the Serbian ruler, giving him valuable time to prepare his forces.
When he was ready, Vukan attacked the Byzantines near Lipenion and inflicted a heavy defeat upon them. John travelled to Constantinople to explain his defeat to Alexios, but was not relieved of his post.
In 1096, he received and hosted Count Hugh I of Vermandois, whose fleet had shipwrecked off the coast of Dyrrhachium.
John was probably still doux of Dyrrhachium in 1105/06, when he is recorded by Anna Komnene to have been defeated in a campaign against the Dalmatians. Marriage =.
To defend himself against the accusation, John travelled to Philippopolis, where Alexios resided.
