Few is known about Istvan's life before moving in Bohemia. His parents were both killed by Turks and he remained orphan. He then met Erik, another orphan as him, who became one of his most trustworthy man, and probably even his lover. Later, King Sigismund of Luxembourg, made him a nobleman and welcomed in his court.
In 1403, few moments before the attack on Silver Skalitz by Sigismumd, Sir Istvan had a meeting with the local Lord, Sir Radzig Kobyla. His hurry to leave the village revealed that Istvan was aware of the imminent attack, although he didn’t warn Radzig.
After the attack, Istvan sent Runt, another one of his trusty man, and his gang to take all the goods remained in the village. After they were looting, Runt and the others incurred into Henry, the son of the local blacksmith who was trying to bury his parents who remained killed in the attack. Runt and his man were lucky: they nearly killed the boy and took a beautiful sword from his scabbard, which gifted then to Sir Istvan.
It is hinted at that Istvan was a homosexual and that his partner was Erik, his right hand man.