In Assassin's Creed II, Leonardo da Vinci helps Ezio Auditore by creating and modifying specialized equipment.
Leonardo is introduced as a close friend and technical ally of Ezio. He deciphers pages from Altaïr’s Codex and uses the information to improve Ezio’s weapons and tools, including the hidden blade. His workshop also provides a recurring place where Ezio’s gear and story advance together.
The most spectacular invention is the flying machine used during a mission in Venice. The game draws on Leonardo’s real studies of flight, but the playable machine and its role in Ezio’s adventure are fictionalized. Leonardo also appears in later parts of the campaign, reinforcing the connection between Renaissance science, art, and engineering.
Other historical figures in the game have different functions. Machiavelli becomes a major Brotherhood associate, Lorenzo de’ Medici belongs to Florence’s political world, and Botticelli is associated with art. Leonardo is the character specifically linked to Ezio’s inventions and technical upgrades.