- "When I was a child, we were taught that the nobles were just and kind. I believed it, too. Though my father was only a cobbler and my mother a scullery maid, I aspired to be much more. I studied hard, I persevered, but the nobles would never have me."
- ―Antonio, regarding Venetian society, 1485.[src]
Raised in poverty from birth, Antonio was unable to attain a wealthy lifestyle, eventually resulting in his founding of the Venetian Thieves Guild. Targeting the rich and wealthy of the city's population, Antonio also improved his position in the Assassin Order, realizing that members of the Templar Order had dug their way into Venice's corrupt nobility.
Eventually meeting with Ezio Auditore da Firenze, an Assassin-in-training on a quest for vengeance, the pair worked together to thwart the Templars' plans to take over Venice. After a failed attempt to infiltrate the Palazzo della Seta by the thieves, Ezio eventually managed to do so with their help, resulting in the successful assassination of Emilio Barbarigo. The thieves then took over the Palazzo for themselves, turning it into their new base of operations.
Ezio later discovered that the Templars planned to kill Doge Giovanni Mocenigo, and requested Antonio's aid. After scouting the Doge's Palazzo, Ezio and Antonio rushed to Leonardo da Vinci's workshop, requesting the use of his flying machine. Antonio ordered his thieves to set fires around Venice, allowing Ezio to gain altitude whilst using the machine due to the heated air. Dodging arrows fired by shocked guards, Ezio glided onto the Palazzo rooftop and eventually succeeded in assassinating Carlo Grimaldi.
During the next few years, Antonio once again assisted Ezio with taking down high-ranking Venetian Templars, introducing him to Sister Teodora whilst plotting the assassination of the Templar Doge Marco Barbarigo, and later introducing Ezio to the Doge's successor, Agostino Barbarigo, before directing him to the mercenary Bartolomeo d'Alviano to gain support in taking down Silvio Barbarigo.
Born in 1443 to a poor family, Antonio lived with his father, a cobbler, and his mother, a maid for the Bellini family. Between apprenticeship sessions with his father, he taught himself to read and write. He was denied entry to the University of Padua, due to his social rank. He applied to several other Italian schools, but was denied entry to all of them. Realizing that hard labor wouldn't allow him to achieve his aspirations, the disillusioned and bitter Antonio resorted to stealing. Around 1469, he robbed the estate of the University of Padua's rector. 
Eventually, Antonio found his way into the Order of Assassins, and subsequently set up the local Thieves Guild. Antonio and his fellow thieves consented only to steal the property from the largely immoral Venetian nobility. He considered his guild more of a "business" than a crime syndicate. In 1475, an orphan called Rosa attempted to pickpocket Antonio. But rather than reporting her to the police, he took her on as a pupil.
Infiltrating the Palazzo
- "You may not share our motive, but I know you share our goal."
- ―Antonio to Ezio.[src]
During 1480, Ezio Auditore arrived in Venice and encountered a bid by thieves to murder Emilio Barbarigo in the Palazzo della Seta, and assisted them by bringing Rosa to safety after the failed attempt.
Made aware of the Assassin's presence in the city, Antonio informed Ezio that he knew of his deeds through the guilds in Florence and Tuscany, praising him whilst commenting that his methods of execution were slightly unrefined. Antonio was aware of Ezio's intentions to kill Emilio, and declared that they would need to draw up new plans and prepare for the assassination discreetly.
Antonio also informed Ezio that there were three traitorous members of the guild who were covertly delivering information to Emilio and recommended their elimination. Ezio agreed with the matter and proceeded to kill the three traitors, with Antonio asking Ezio to assist in their other duties, before the thieves were once again ready to attempt Emilio's assassination with the help from Ezio.
Their plan lasted for four years, and with the final step completed, which required Ezio to dispatch the archers patrolling the rooftops surrounding the Palazzo, he met up with Antonio, Rosa and Ugo. Ezio proceeded to take the lives of Emilio and the guards stationed within the Palazzo, and then he and Rosa opened the door for Antonio when the task was finished.
Antonio told his thieves to return the items that Emilio had stolen from the civilians of the district, and handed Ezio a monetary reward for his role in the assassination. Ezio informed Antonio that Emilio had been speaking with an individual that was unknown to him, after which Antonio gave Ezio the name "Carlo Grimaldi". Antonio asked Ezio on what he planned to commit to next, which he responded that he had a "meeting to attend". Ezio bid farewell to the thieves and subsequently departed the Palazzo.
Infiltrating the Basilica
- Ezio: "Carlo Grimaldi and the Barbarigo are in league with the one they call The Spaniard. They're going to murder the Doge and replace him with one of their own. They will have all of Venezia, her entire fleet, in their grasp."
- Antonio: "And they call ME a criminal!"
- ―Antonio learns of the Templars' plan to execute the Doge of Venice from Ezio Auditore.[src]
Ezio later discovered that Carlo Grimaldi planned to kill Giovanni Mocenigo with poison and replace him with the Templar Marco Barbarigo. Ezio quickly traveled to Antonio and told him of the Templars' intentions, to which the pair sought an entry point into the Doge's Basilica, but despite observing all the possible entrances, they were unable to find an effective approach.
Antonio exclaimed that the situation was hopeless, and that only birds were able to gain entry into the building, giving Ezio the idea to seek assistance from his close friend Leonardo da Vinci.
Antonio later visited Ezio, and the Assassin introduced him to Leonardo. Anxious, Antonio informed Ezio that Carlo was in possession of the poison and that they would have to make haste in order to catch him in time. With this, Ezio attempted to control Leonardo's flying machine, but he crashed almost immediately.
Frustrated at his invention failing, Leonardo did not know how to extend the machine's flight capabilities until he threw a piece of paper into the fireplace, giving him the revelation that heated air would allow the craft to gain altitude during flight.
Going along with the discovery, Ezio was to clear some of the guards stationed on the rooftops in areas in Venice, and Antonio was to send his men to burn a sequence of fires spread across the city. Once Ezio had disposed of the guards, he met with Antonio and Leonardo on a rooftop, seeing in the distance that the fires had been successfully lit. Antonio told the others that he hoped the plan would work, as they were running out of time, to which Ezio urgently flew off on the flying machine.
Aiding in the Doge's murder
- "Perhaps it was wrong of me to doubt so readily, now we shall see where all the pieces fall."
- ―Antonio to Ezio.[src]
Over time, Antonio and Leonardo developed a mutual friendship, and at one point Leonardo was able to inform Ezio of Antonio's whereabouts. Ezio sought out Antonio and the assistance of Teodora Contanto, and found the pair in the brothel La Rosa della Virtù. Upon his arrival, he removed his Carnevale mask to reveal his identity to Antonio, after which Antonio introduced Ezio to Teodora.
The trio then discussed the plans to kill the new Doge, Marco Barbarigo. However, before they had time to go into details, a man ran out, having killed a courtesan and stolen her florins. Teodora then sent Ezio to kill the man, whilst she and Antonio awaited Ezio's return.
Once Ezio had returned from the errand, Antonio discussed killing Marco with him and Teodora, whilst the girls mourned the loss of one of their own. They came to the conclusion that Ezio would need to win a golden mask from a series of Carnevale games, granting him entry to the Doge's party during the festival.
Along the way, the three engaged in conversation as they walked to their destination. Upon their arrival, Ezio took part in the games and won all three challenges, but failed to obtain the mask. Back at the brothel, Teodora and Antonio became aware of the bribe that was given to the games' judge by Silvio Barbarigo whilst Ezio was fighting Dante Moro. Following this, a courtesan came in, telling them that Dante was heading for the party.
Ezio planned on killing Dante to obtain the mask, however, Antonio warned him to desist, in fear that the secretive and paranoid Marco would immediately cancel the party, to which he recommended stealing the mask instead. Ezio then left, leaving Antonio waiting for news of the deed. Once the theft was completed, Ezio returned and Antonio admitted that he had judged Ezio too readily.
Acquisition of the Apple
- "We have our prize, but there is much to be done."
- ―Antonio to Ezio regarding the Piece of Eden.[src]
Ezio later visited Antonio in the hope of finding Silvio and Dante, and Antonio introduced Ezio to Marco's brother, Agostino Barbarigo, before he informed the Assassin-in-training that the pair had fled into the Arsenale di Venezia.
Ezio asked if Agostino could force Silvio's men to stand down, but the Council of Ten was yet to confirm his ascension. With this, Ezio desired to build a personal army, to which Antonio responded by telling him to seek out the experienced condottiero Bartolomeo d'Alviano.
Whilst Ezio was fighting Rodrigo Borgia for the Piece of Eden, his other associates, including Antonio, came to the young Assassin's aid. Together, the group took down Rodrigo and his guards, and though the Grand Master of the Templar Order fled, Ezio acquired the Piece of Eden.
At that point, Ezio was unaware of his affiliates' motives until Niccolò Machiavelli revealed to him that they were all Assassins. From there, Ezio was handed a map that led to a tower and was told to meet them that night for his initiation into the Order. During the ceremony, Ezio was given a ritual burn mark on his finger, ending with the Assassins all performing a Leap of Faith off of the tower.
Visit from Spain
- "Santangel contacted the thieves' guild from España. When we met, he explained his plight and that's when I contacted you."
- ―Antonio to Ezio, about Luis' sudden appearance.[src]
During 1491, Antonio was contacted by Luis de Santángel to complete a task for the him. Antonio referred the minister to Ezio, whom he mentioned was the "deadliest man in Italia". After this, he later explained to the Assassin that Luis was seeking protection for himself and his friend Christopher Columbus.
Refusing at first, Ezio accepted when he was told that they were to meet with Rodrigo in Venice. From there, Ezio left to assist Columbus, and when he returned, he revealed to Antonio that the entire meeting had been a trap.
After Antonio informed Ezio of Luis' location, the Assassin left to speak with him in the Garden District, in case anything unfortunate were to occur. He also placed the pair in contact with the Thieves Guild located in the Spanish city of Barcelona, before Ezio traveled there to deal with the Inquisition.
Journey to Rome
- Mario: "For years... No, decades... We have sought these answers."
- Antonio: "But so too could the Spaniard... And if he does... if he finds a way into the Vault... Its contents will make the Apple seem a trifling thing."
- ―Antonio giving his input at the meeting.[src]
Antonio met with the other Assassins at Monteriggioni in 1499, as they formulated a plan to prevent Rodrigo from accessing the Vault. Ezio used the power of the Apple to highlight the Vault's location on a map that was hidden underneath the Codex pages.
Once they have discovered it was in Rome, the other Assassins agreed to create distractions throughout the city in order to give Ezio an opportunity to infiltrate the Cappella Sistina and kill Rodrigo.
Personality and characteristics
- "Ezio, who are the true nobles of Venezia? Men like Carlo Grimaldi and Marco Barbarigo? No! I say we are; the thieves and mercenari and whores."
- ―Antonio expresses his feelings towards the social classes.[src]
Antonio was a man who greatly honored justice, and for this reason, he and his thieves only stole from the rich and corrupt citizens of Venice, leaving the poor to live in peace.
He was of the opinion that the thieves, mercenaries, and courtesans, who were often considered the lower class, were in fact the heroes of their society. Inversely, Antonio also had a strong dislike for the corrupt nobility, who only sought to make their subjects into playthings.
The leader of the Thieves Guild displayed a trustworthy attitude, and was always willing to lend a helping hand when needed. Antonio introduced Luis de Santángel to Ezio, in order for the latter to assist his friend. However, Antonio was easily agitated when plans did not come together, or when he and his allies were unable to solve a problem.
Accompanying this, Antonio also showed great care for his thieves, especially Rosa, and always did his best to keep them safe from harm; which caused the members of the Venetian Thieves Guild to admire and respect their leader.
- The "courier disguise" in Assassin's Creed: Project Legacy was identical to Antonio's attire.
- Antonio could be unlocked as a usable character skin for Ezio in Assassin's Creed II: Discovery, though the mission dialogue remained the same.