Borgia messenger
Borgia Messengers, also known as Borgia Couriers, appear in the game Assassin's Creed II. Upon spotting Ezio, the messengers take flight, performing many free-run actions and acrobatic stunts, such as climbing walls and swinging from posts. If Ezio manages to catch up to one, he can tackle him or simply throw a Throwing Knife at him for a considerable amount of Florins, with about 1500 florins per messenger. However, if Ezio kills one, his notoriety will automatically increase by 50%. However, Ezio can still get the 1500 florins (or more) if he loots the messenger. If caught, the Courier begs for his life. After being attacked or left alone a few moments, the Courier will resume his free-running.
Presumably, the Messengers carry important information or funds for Rodrigo Borgia, as they are called Borgia Messengers.
Interestingly, Archers begin chasing the messenger as well if he climbs onto a rooftop in his flight. It has also been shown that you can trip Borgia messengers so that they fall to their death.
If you intercept one of them, you get the Achievement/Trophy "Mailman" (10G)
Unlike Pickpockets, who have a red icon, Borgia messengers are invisible on your map.