Josef was born and raised in the Jewish Quarter of Prague. The son of a rabbi, he expected to follow in his father's footsteps. When he was twelve, his father grew ill and died. His dreams of scholarship died with him as he was apprenticed to a butcher to support his family.
Violence against Jews was not uncommon, and Josef suffered most brutally one night when a gang of Christian boys crushed half his head in, broke and smashed his nose, and dislocated his jaw. He would have died if not for his Embrace by the Nosferatu Yehuda. The Cainite asked Josef, still on the brink of death, if he desired revenge, but Josef said he did not. Yehuda asked if Josef would defend others from such brutality to which Josef could only squeeze the Nosferatu's hand in response.
After Yehuda taught Josef what he needed to know of Cainite existence, the Nosferatu elder headed east, leaving his childe behind. Josef took up the cause of the ghetto, protecting its rabbi and people. Violence against Jews was ecked out in turn by the Nosferatu avenger. The other Cainites of Prague largely ignored the ghetto, so Josef was able to claim it as de facto domain.
His great shame was, however, that he was partially responsible for the violence against his people. He was cursed with an irresistible desire for the blood of children and so he feeds exclusively from Christian and pagan youth. He cannot help himself, though he regrets the death of children when it inevitably occurs.
Constant power struggles between Prince Rudolf Brandl and Josef over his domain eventually led to an ultimatum. Open the Jewish Quarter to Brandl's allies to feed or face destruction. Josef stood his ground and faced the Final Death that night by the minions of the Ventrue Prince of Prague. Instead, Josef fled into the catacombs under Prague Castle, which was Brandl's haven, and waited until the sunrise. Then, under cover of day he crept out from the tunnels and slayed the prince while he slept.
In the ensuing power vacuum, Josef was able to gain sufficient allies from the Brujah elder, Ecaterina the Wise, and Garinol the Cappadocian, to secure Prague for himself, This ensured Prague would remain a safe haven for Jews in Europe for the next 740 years of his reign. The other deciding factor in Josef's claim to Prague was his unholy alliance with Shaagra the Destroyer, though few knew of this affiliation with the Tzimisce methuselah. Shaagra thought that Zvi was its pawn, but in secret, the Nosferatu fed the Tzimisce distorted information to keep it asleep.
Little is known of Josef's long rule of Prague until modern nights, nor if his taste for Christian and Pagan children abated or ceased. What is known is that he fell to Nazi flamethrowers even as he led local resistance against their regime in the 1930s.