In 1753, Lucio was participating in the Corsican struggle for independence against the Genoese, when he was targeted by the Templar Haytham Kenway. Lucio's mother Monica was being held hostage by Reginald Birch to decode a journal containing information on the First Civilization, but she was unable to complete her work without her son. With this in mind, the Assassin Order sent Miko to guard Lucio, to prevent him from falling into the hands of the Templars.
While Miko was distracted during a Genoese attack, Haytham posed as an Assassin sent to take him to safety, but Lucio wanted to help fight. Haytham then claimed he had been sent by Monica, to which Lucio became suspicious, so Haytham simply knocked him out and took him away.
Lucio was eventually taken to Birch's chateau near Troyes, France, and was imprisoned with his mother in the cellar while decoding the journal. Haytham objected to this, and forced Birch to swear that they would be released safely once their work was done.
In 1757, Haytham discovered Birch was behind his father's murder and attacked the chateau. Following Birch's death, Jim Holden freed Lucio and Monica, and Haytham offered them food, horses and his own sword for the journey home. Lucio took the sword and vengefully plunged it into Haytham's chest, unable to forgive Haytham for subjecting him to his fellow Templars' harsh treatment. Before falling unconscious, Haytham ordered Holden to spare Lucio and Monica, to which Holden complied; Lucio and his mother then escaped from the chateau.