The tradition derives itself from an ancient Siwan ritual, with the feather representing the Feather of Ma'at, that souls would weigh their hearts against in the Duat. In particular, Medjay Bayek and his wife Aya used heron feathers in their rituals after killings their targets. After they killed their targets, they would dip the feather in their target's blood and leave them for the Lord of the Duat to judge. This tradition would continue after they established the Hidden Ones, which would eventually evolve into Assassin's Brotherhood.
High Middle Ages
After investigations on the target had been completed, Assassin bureau leaders would give the chosen Assassin a feather, allowing them to proceed with the actual mission. Upon killing his target, the Assassin would stain the feather with the blood of the slain, and present it to the Bureau leader.
Among Assassins, the phrase "having a feather on one's head" meant a mark of death. For example, an informant in Damascus once commented that "a feather laid on top of Abu'l Nuqoud's head," implying that the Merchant King was marked for assassination.
As he was sickly and often confined to bed, Petruccio Auditore once asked his brother Ezio to collect feathers for him. Though Ezio asked him what they were for, he only said that it was a secret, which he would reveal in time.
After the murder of Ezio's father, Giovanni Auditore da Firenze, and his two brothers, Federico and Petruccio, his mother Maria was struck to silence for years. She would only remain praying over Petruccio's feathers in her room in the Villa Auditore, in mourning for her lost child.
In an effort to resolve this, Ezio sought to collect feathers, both in memory of his brother and to coax his mother into speaking again. As he traveled across Italy, he gathered and placed any feathers he found into a box in his mother's room.
After Ezio had collected fifty feathers, Mario Auditore spoke with him about what he was doing, suggesting that he should give up in what he believed to be a wasted effort. In an attempt to have Ezio turn his attention to other matters, Mario also let him know that a new weapon, the Condottiero War Hammer, was waiting for him at the Monteriggioni blacksmith.
After collecting one hundred feathers, Ezio's efforts were rewarded. Maria spoke again for the first time in years, thanking Ezio for not giving up on her, and presenting him with the Auditore Cape.
In later years, even after the fall of Monteriggioni, Ezio would continue to collect feathers in Rome; particularly those found on landmarks throughout the city. He placed these feathers in a chest at the Tiber Island headquarters, which resembled the feather box that had once been kept in Maria's room.
American Revolutionary War
During one instance in 1769, Ratonhnhaké:ton and Kanen'tó:kon gathered feathers from nests nearby Kanatahséton at the request of the Clan Mother of their village. During the course of the American Revolutionary War, Ratonhnhaké:ton could also collect other feathers in memory of his village.
Before the fall of the Assassin Order, an Assassin safehouse disguised as a dry-cleaners used photographs of feathers, coupled with the codeword "Rafiq", as proof of identity. However, the Templars, with the help of Daniel Cross, used this information to identify the safehouse and launched an assault.
- Proximity to a feather was signaled by a 'shimmering' sound effect identical to the ones heard near treasure chests, glyphs and Codex pages, as well as the decipher fragments in The Lost Archive.
- Assassin's Creed II
- Due to his death, it was never revealed why Petruccio collected the feathers in the first place; although a line from the novelization suggested that they were meant to be a present for his mother.
- Collecting all 100 feathers unlocked the achievement "In Memory of Petruccio".
- If Ezio placed all 100 feathers at once in Maria's feather chest, the cutscene with Maria occurred before the one with Mario.
- If one were to begin collecting feathers in Florence before arriving at Monterigionni, the Animus would still provide the message stating that feathers could be returned to Maria's room there.
- Assassin's Creed: Brotherhood
- Collecting all 10 feathers unlocked the achievement "In Memoriam".
- After Sequence 4, a map detailing the locations of all the remaining feathers could be bought from any art merchant.
- Maria's feather chest was an artifact that could be found in modern Monteriggioni by Desmond Miles.
- Assassin's Creed III
- All feathers were found in the Frontier, and a map detailing their locations could also be bought from general stores.
- Collecting all feathers unlocked the outfit Ratonhnhaké:ton wore before becoming an Assassin.
- Assassin's Creed: Syndicate
- Jacob and Evie Frye used handkerchiefs to mark successful assassinations rather than using feathers.
- Assassin's Creed: Odyssey
- The Hedonists also had a ritual of collecting feathers. Herodotos believed it a futile endeavor that no one should emulate.