His story begins as a quest for revenge, but he soon learns through friends such as Leonardo da Vinci and Niccolo Machiavelli that he serves a grater purpose and is actually the lynch-pin in the Assassins' ongoing war with the Templars.
Roderigo Borgia relentlessly pursues two specific Pieces of Eden throughout the game, and eventually gets his hands on the Apple of Eden and the Papal Staff.
Ezio confronts him before he uses the combined Apple and Staff to open a vault within the Vatican to access a Prophecy that's meant to win the war for the Templars.
Ezio defeats Roderigo, enters the vault and is greeted by a hologram representing a race known as 'The People Who Went Before'.
The hologram calls herself Minerva, and refers to Ezio as The Prophet, explaining that his purpose is to reveal her message to Desmond.
The message is this: the earth will be destroyed by a solar flare in 2012, similar to the one that once brought mankind to the brink of extinction. The vault, along with other temples throughout the world were built by The People Who Went Before to help mankind avoid the tragedy again.
Ezio is confused by the message. Meanwhile, back in the present day, the Assassin safehouse is raided by Abstergo employees lead by Dr Vidic.
Desmond, now brimming with Ezio's skills, fights off the attackers but Vidic escapes. The Assassin team flee with their Animus in the back of a truck.
That's where Brotherhood begins...
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