Abbo of Cernuus was a Benedictine monk from Neustria and secretly a member of the Hidden Ones who operated in the Carolingian Empire during the late 9th century, operating under the pseudonym of AC.
Abbo Cernuus was believed to have been born in the middle of 9th century. At some point, he was inducted into the Frankish Hidden Ones, inheriting the mantle from the few Hidden Ones who opted to remain behind after their mass departure from the Roman Empire's provinces of Britannia and Gaul in the 5th century. Like his predecessors, Abbo dedicated himself to keeping the former bureaus in Paris and the surrounding Frankish cityside safe.
Abbo eventually found his calling as a monk and found a placement at the the Abbey of Saint-Germain-des-Prés, where he studied for many years. When the Elgring Clan chieftain Sigfred led the Vikings in their attack on the city in 885, Abbo helped in its defense, personally eliminating six raiders who broke into the church aiming to steal holy relics from the sepulchre.
As Abbo had been wearing his hooded Hidden Ones robes at the time, this eventually gave rise to the legend among the surrounding populace that the cloaked figure sometimes seen on the abbey roof was Saint Germain's ghost protecting holy ground. Wanting to keep his dual identity a secret, Abbo let the rumors continue unabated.
At the same time, a group of Christian zealots known as the Bellatores Dei gradually rose in power and soon found the Hidden Ones' locked Roman-era bureaus in Champlieu, Gisacum, and Diodurum. Although they had no knowledge of the Hidden Ones' origins or purpose, they sought to open the rooms and claim what secrets lay within. In accordance with the Creed's directive to protect the Brotherhood at all costs, Abbo took it upon himself to defend the ancestral headquarters, swiftly assassinating the teams of soldiers who attempted to excavate and break into them.
During her time in Francia, the Viking jarlskona Eivor Varinsdottir of the Raven Clan managed to unlock the entrance to the Hidden Ones' abandoned bureau in Paris and explored it. Before Eivor could leave, she heard the soft footsteps of Abbo, who had left her a strange letter signed "AC" with an apology for the dead soldiers and a poem:
- "This place of honor forever holding, the deeds that were done
We abide always many in number, yet together are one
Whose firm faith and whose lonely labor, serve only the fight
I must yet stay unknown in the darkness, so you may work in the light."
Respecting AC's request to remain anonymous, Eivor decided to keep the short sword Joyeuse as a gift after unlocking it from inside the bureau. Leaving the bureau, Eivor later investigated the Abbey of Saint-Germain-des-Prés, where she found a dead body and an account of a cloaked figure guarding the place from unwelcome visitors. This loosely corroborated with AC's recent actions and their poem which said they worked alone and unknown, and matched directly with what Eivor had overheard from some civilians while in the area, though she failed to discern that the "ghost" and "AC" were one and the same.
Following the siege, Abbo wrote the poem De bellis Parisiacæ urbis or Bella Parisiacæ urbis ("Wars of the City of Paris"), a chronicle detailing the siege and its aftermath.
Behind the scenes
In database entry for Francia, he is named Abbo of Cernuus rather than Abbo Cernuus. This is incorrect, as cernuus is Latin for "the crooked" and should not be formatted as a toponymic or patrial byname.
On 7 September, 2021, the official Assassin's Creed Twitter revealed Abbo of Cernuus as the identity of "AC".