Prior to joining the armed forces of the Second Bulgarian Empire, Ivan the Russian may have been a military commander in the service of the Hungarian governor of Severin.
[1] Hungarian sources from 1288 make notice of one Russian named Ivan (Iwan dicto Oroz) as an ally of the ban of Severin, Theodore Vejtehi from the kindred Csanád,[2] who was one of the nobles that opposed the rule of Charles I of Hungary in 1316–1317.
Thus, as the Hungarian king established his authority over Severin and suppressed Vejtehi's rebellion, Ivan the Russian may have fled to Vidin and entered the service of Michael Shishman.
[3] Before that identification was proposed, it was considered that Ivan had arrived in Bulgaria after fleeing the Mongol conquest of Rus', much like another Russian in Bulgarian service, Jacob Svetoslav.
With a one-thousand-strong cavalry force of Alans, Bulgarians[6] and possibly Hungarians[1] and two thousand infantrymen, Ivan was to defend the city from Byzantine raids.
[10][11] Despite the elaborate siege tactics, by the summer of 1323 the Bulgarians had not only retained the city, but also launched raids on nearby Byzantine-held fortresses in the Rhodope Mountains, such as Stenimachos (modern Asenovgrad) and Tsepina.
In a suitable moment, the Bulgarian guard would arrest the emperor and take hold of the palace before allowing Michael Shishman with a large army and Tatar mercenaries into Constantinople.
While Ivan stuck to the plan and signed an oath that he had come with peace to persuade the Byzantines, he promptly retreated to Bulgarian territory upon receiving that order from Michael Shishman.
In the eyes of Pavlov, despite his foreign origin Ivan the Russian was not considered an emigrant or a mercenary by the Bulgarian nobility and the emperor, but rather a trusted commander and one of their own.