In Assassin's Creed II, what is the name of the hidden blade inventor who becomes Ezio's ally?

Leonardo da Vinci is the hidden blade inventor who becomes Ezio's ally in Assassin's Creed II.

In the game, Leonardo is a gifted artist, engineer, and inventor who helps Ezio understand and maintain Assassin equipment. He studies the Codex pages left by Altaïr and uses their designs to build or improve tools, including Ezio's hidden blades. His workshop moves as Ezio travels between major Italian cities.

Leonardo's friendship with Ezio also gives the story a historical connection to Renaissance intellectual life. The real Leonardo da Vinci lived from 1452 to 1519 and worked in Florence, Milan, and other Italian centers. He was known for paintings such as The Last Supper and the Mona Lisa, as well as notebooks filled with studies of mechanics, anatomy, and flight.

The game fictionalizes Leonardo's involvement with the Assassins and hidden-blade technology. His historical identity, artistic career, and association with Renaissance Italy are real, but there is no evidence that he designed weapons for a secret Assassin order. Machiavelli and Lorenzo de' Medici are also historical figures who appear in the game, but neither is the inventor of Ezio's blades.