Pio

Father Pio was a priest of the Basilica of Santa Croce, the principal Franciscan church in Florence.

He was a good friend of Niccolò Machiavelli, one of the leaders of the Assassins in Italy. As a result, when Borgia forces took over the cathedral by force one night around 1506, locking down the entire courtyard, Pio was the one to alert Machiavelli. The Assassins responded by sending an agent, Lo Sparviero to investigate. Later that night, Lo Spaviero would kill one of the Templar agents in the courtyard, Vittorio to sow chaos in the Borgia forces, allowing him time to intimidate a Crow messenger into giving him his letter.

Reference

 * ''Assassin's Creed: Identity