Federico Auditore da Firenze

"It is a good life we live, brother."

- Federico to Ezio

Federico Auditore da Firenze was the eldest son of Giovanni Auditore and Maria Auditore, the older brother of Ezio, Claudia and Petruccio and the nephew of Mario Auditore. He was a witty, sharp and funny individual who liked to tease his little brother Ezio, but wouldn't tolerate it if someone else harmed him. He started his training as an Assassin with his father before Ezio, who was unaware of this at the time.

Assassin's Creed: Lineage
Federico was eating dinner with the rest of the Auditore family as Giovanni left to intercept Rodrigo Borgia.

He later played a game of chess against Ezio, and beat him at it quite handily.

When Antonio Maffei showed up at the house of the Auditore and tried to capture Giovanni for the first time, Giovanni, having not yet recovered from his last fight, elected to escape. He told Federico to buy him time, telling him to "protect the family" at all costs. Federico succeeded in delaying the guards long enough for Giovanni to leave. Federico then kicked them all out of the mansion, reminding them "not to doubt the word of an Auditore again"

Assassin's Creed II
As his brother Ezio was fighting against a member of a rival noble family, Vieri de' Pazzi, Federico showed up to help his brother. He proved to be an excellent fighter, and it can also be noted that he probably taught Ezio how to free run. After Ezio and he won the fight, Federico instructed Ezio to loot money from the defeated enemies. After Ezio did so, he directed him to a doctor. It is said that Federico worked in one of the Medici banks, but was eventually removed from the payroll due to his slacker personality, and also after putting money on the roof of the bank as a prank. Being an Auditore, he was saved from harsher consequences. Federico also enjoyed teasing his younger brother after the fight, when they visit the Doctor who treated the cuts Ezio had received on his face. Afterwards, he and Ezio climbed to the top of the nearby church and took in the sights of Florence.

The next day he lounged about at home while Ezio ran around doing errands for their father, whereby Ezio teased him for this with little insults. Federico was later beaten and captured by the city guards, along with his father Giovanni and little brother Petruccio. He was held prisoner overnight, while Ezio frantically tried to secure the release of his family. The next morning, Federico was hanged with his father and brother, as the victims of a Templar conspiracy. Years later, Rodrigo Borgia would tell Ezio that there was no need to kill Federico and Petruccio; he just wanted to make a point.

It is not clear how much about his true heritage Federico knew, if any, but he seemed to take Giovanni's instruction to "protect the family" to heart; as evidenced in his appearance at the beginning of Assassin's Creed II, no doubt making sure Ezio did not get himself seriously hurt while fighting the Pazzi. It is clear that Free Running was taught to him by Giovanni, and he in turn probably taught it to Ezio (as mentioned above).

Trivia

 * Federico heavily resembles Francesco I de' Medici in his late teenage years, both in attire and facial properties.