Born into the House of Contarini, one of the founding families of Venice, Bonacolto joined the Templar Order at some point. After the Templars, particularly the House of Pazzi, had been driven out from Florence thanks to the efforts of Assassin Ezio Auditore da Firenze, they sent Bonacolto to reestablish their influence in the city.
In 1493, Bonacolto entered Florence and used his family's riches to strong arm merchants and officials to recruit them to their cause. He would then kidnap those who refused and kept them captive in an old wine cellar near an abandoned Contarini manse, intending to sell them as slaves to foreign merchants. He would also order his guards to patrol the streets of Florence and keep watch for any Assassins that would interfere with his plans.
True enough, Ezio, now a Master Assassin, heard of the Templar resurgence while in Venice searching for Girolamo Savonarola. He called for aid from the Assassin brotherhoods in Europe, particular the Spanish Brotherhood who sent a team of Assassins to assist him. With additional help by Corvo Antonelli and Perina di Bastian, they were able to eliminate the Templars in the city and drive Bonacolto out.
Bonacolto soon withdrew to an ancestral keep in the countryside in an attempt to wait out for reinforcements. However, the Assassisn were able to storm the keep and eliminate his guards before assassinating Bonacolto.
- The model for Contarini recycles the model for Diego de Alvarado, an Assassin also featured in Assassin's Creed: Rebellion, only changing the color palette of the outfit and adding a scar on the right eye.