In Game Bio:
Date of Birth: 1456.
Profession: Student, Noble.
Ezio's older brother, and the eldest Auditore, Federico entered the Medici bank as a clerk when he was 19. However, the bank logs indicate he mostly dicked around rather than actually working.
One entry goes into detail. On September 17, 1475, a bag of gold florins went missing: "After panic struck the bank, the elder Auditore approached Francesco Sassetti, and with a smile revealed the location of the bag, which had been hidden on the rooftop! If he weren't the son of Giovanni Auditore, I'd speak to Lorenzo de' Medici and have him put in stocks!"
Unsurprisingly, Federico was removed from the bank's payroll shortly after his 20th birthday.