 Born in Nafplion in the Peloponnese, Mercurio was the son of Peter Bua ( 1450s), who belonged to the Albanian noble family of Bua that settled in Peloponnese, and who was the leader of the Albanian community of the region after the fall of the Despotate of the Morea.His uncle Constantine Arianiti, a nobleman of the Holy Roman Empire, was the Count of Montferrat.Due to his martial prowess, he was eventually made Count of Aquino and Roccasecca (of the Holy Roman Empire).