Cicero served Maximus while the latter was still a General in the Roman Empire. He and Maximus were homesick, and Maximus told him they'd probably never go home. Whilst in conversation, Maximus asked Cicero to fetch his sword, which was behind a veil. Whilst Cicero was doing this, (newly-promoted) General Quintus, under orders from Commodus came in with many armed guards. He asked Maximus not to fight. Cicero, being behind the veil with Maximus' sword, begin to draw it, to fight, but Maximus subtly shook his head, indicating he did not want Cicero to be discovered.
Later on, during Maximus' fight with the legendary Tigris of Gaul, he witnessed the battle and saw the assassination attempt by Commodus on Maximus by sending three tigers to attack Maximus. When Maximus left victorious, Cicero told him with excitement that his armies remained loyal to him.
Cicero's role in the coup was to wait for maximus outside the city gates with two horses and take him to where the army was camped. Maximus found him, and whistled like a bird (to check with Cicero it was safe). However, Lucilla had told Commadus of the plan. Cicero screamed "Maximus!", and was then hung by the Roman Army (He had already been noosed). When Maximus ran over and tried to cut him down, Cicero uttered "I'm sorry", before an archer ended Cicero's life with two arrows to the chest.