Instructions
Find Petruccio, Ezio's younger brother, at their family home in Florence. He will ask you to pick up a feather for him. This is the first time you collect feathers in the game. Once you give them to Petruccio, you will continue to find and collect more feathers throughout the rest of the game.
Collect three feathers. They are hidden in places that can be spotted by running across rooftops in Florence. Walk around rooftops with Eagle Vision on to see the feathers, which will appear as a white glitch graphic. When you see a feather, walk Ezio over it and he will automatically pick it up. The feather will instantly appear in your inventory. Return to Petruccio once you have picked up three feathers and speak with him to give him the feathers.
Find all 100 missing feathers. They are located in all of the major cities and locations that you visit throughout the game. Locate any feathers that you missed by pausing the game and going to the DNA strand in the menu. At the end of the strand, you will find a section that will show you on the map where the feathers are.
Go to the Villa once you have collected all 100 feathers. Walk up the main staircase to reach the second floor. Walk over to the right wing to find Maria's bedroom. Enter her bedroom and place all 100 feathers in the small wooden box near where she is standing. Talk to Maria to get the Auditore Cape.