In 259, Aquilus was tasked with the assassination of several high-ranked individuals within the Roman Empire. Having failed to assassinate his third target, General Gracchus, Aquilus met up with his cousin Accipiter – an Aleman and a fellow Assassin – from whom he obtained an ancient artifact known as the "Ankh", formerly held by the Egyptian goddess Isis.
After his father was murdered and the Ankh was stolen by the Roman Senator Caïus Fulvus Vultur, Aquilus traveled from Lugdunum to the Empire's capital of Rome, seeking vengeance. Successful in his objective, he returned home with the artifact, discovering more of its abilities. Eventually, Aquilus was executed by Roman soldiers.
As Aquilus entered the Roman camp, he asked to see General Gracchus, where he was then directed to the center of the camp, and his message was delivered to the Roman general.
Gracchus invited Aquilus in and revealed the fact that he had been expecting Aquilus, knowing that he was the one who had previously murdered senator Caius and general Titus.
While he suspected that he was the Assassin's next target, Aquilus attempted to deny it, but was quickly overpowered by the Roman guards and stabbed by Gracchus, who did not want to take any risks with the Assassin, and left him to die.
When Aquilus regained his consciousness, he was laying on a bed and found his wounds tended to. He soon noticed someone sitting besides him, who introduced himself as his cousin Accipiter. Accipiter explained about the battles that had been waged between them and the Romans, telling Aquilus they had just won one.
Aquilus soon asked about the object he was to retrieve, and found out Accipiter had it in his possession. They then agreed that Aquilus would return it as soon as he would be able to ride a horse again.
Not long after, Aquilus had recovered from his wounds, and he ventured to fulfill the plan agreed. With this, Aquilus immediately set off for his hometown, Lugdunum. Once he had arrived, he was greeted by his father Lucius, who stated he had not expected Aquilus to return alive.
He also met an old friend of Lucius, a Roman senator named Caïus Fulvus Vultur. Together, they had dinner, and after the senator went to bed, Aquilus and Lucius spoke of the mission. Aquilus handed the mysterious object to his father, who then showed him the Ankh and explained why it was so important to them.
Aquilus immediately set off to interrogate Faustinus, and caught him off guard by waking him up in the middle of the night. Faustinus soon confessed to betraying them, telling Aquilus he had no choice.
When Aquilus asked Faustinus about his accomplices, he told he was the only one. This lie resulted in Faustinus being beaten up and betraying his accomplice: senator Caïus Vultur.
Aquilus hurried back to his father to deliver the bad news, only to find his calls unanswered. Upon further inspection, he found his father murdered. Aquilus then followed a moaning sound, coming from his father's servant Weke.
Weke had been injured badly and could not be saved, but he did say a few last words, which only managed to confuse Aquilus. A maid then came up to Aquilus, telling him Caïus had fled after killing both Lucius and Weke, and had taken the Ankh with him.
Enraged, Aquilus traveled to the Empire's capital of Rome, desiring vengeance for his father's death. Locating Vultur's residence, Aquilus infiltrated the building, killing a group of guards in the process.
Sparing one, Aquilus forced the man to direct him to Vultur. On being led to Vultur's room, the senator rushed out of the door with a spear, but instead impaled the guard who was forced to assist Aquilus.
Aquilus confronted his father's murderer, yelling at the senator to give him the artifact. Vultur directed Aquilus to the Ankh, and offered to tell him some of the artifact's history. Aquilus agreed, though assuring him that no matter what, he would die at his hands.
Returning home, Aquilus was greeted by his wife Valeria, and the two had a night of intimacy in celebration of his safe return. Aquilus then told his wife of the events in Rome and of the Ankh and its powers. Trying to activate the Ankh, Aquilus found a hologram of Lucius erupting from the artifact.
Lucius' final message was interrupted by a battalion of Roman guards who had broken into their residence, with the order to arrest them. Leading them to a nearby forest for execution, the Roman soldiers were temporarily halted by Accipiter, who had caught wind of the execution.
The Roman soldiers, in a state of panic, executed Aquilus, though did not get the opportunity to kill Valeria.
- "Aquilus" derives from "Aquila", a Latin translation for "eagle"; much like how Altaïr Ibn-La'Ahad, Ezio Auditore da Firenze, Haytham Kenway, Arbaaz Mir, Aveline de Grandpré, and Nikolai Orelov possessed names bearing connections with eagles.