Assassins Creed II
After Claudia's father and two of her brothers (Giovanni, Federico and Petruccio Auditore Da Firenze) are executed unjustly at the hands of the Templars, Claudia and her mother Maria are taken in by Mario, her uncle. For the majority of the game she works as a book keeper working for Mario while her last remaining brother, Ezio, hunts down the Templars that murdered their family.
Assassins Creed: Brotherhood
Following the attack on Monteriggioni, Claudia and Maria moved to Rome with the majority of the characters from the game. Here Claudia volunteered to run a brothel for the assassins. Later on in the game she becomes a member of the assassins.
Assassins Creed: Revelations
Though she does not appear in the game, Ezio writes frequent letters to her describing his adventures.