Gervasius or Geruasius started his ecclesiastical career as a member of the royal chapel during the reign of Géza II of Hungary.
[3] Becoming a member of the royal council, he interceded with Géza II in March 1157 to grant the collection right of salt duties to the Archdiocese of Esztergom at Nána and Kakat (present-day Štúrovo, Slovakia).
[1][4] Still in the same year, Gervasius contributed and permitted the foundation of the Benedictine Abbey of Küszén (later Németújvár, present-day Burg Güssing in Austria) to comes Wolfer, a Carinthian-born knight and ancestor of the Kőszegi family.
After Héder and Gervasius' successful diplomatic mission, Stephen, left the German court for the Byzantine Empire and settled in Constantinople.
[5] Rahewin, who narrated the events in the continuation of Otto of Freising's Gesta Friderici imperatoris, incorrectly referred to Gervasius as "Bishop of Vasvár", which was, in fact, the collegiate chapter of his diocese.