Commodus is one of the main antagonists of Ryse: Son of Rome and is based loosely on the Roman Emperor of the same name.
Commodus is introduced as one of two sons of Nero who were engaged in a war with the Britons - Commodus himself was captured by the Picts and prepared for sacrifice upon the Wicker Man until he was rescued by Marius and his men.
However, far from being grateful Commodus yells at the soldiers who risked their lives to save (calling them idiots and worse) - then upon being freed by Marius screams at him and forces him to give him his cloak, storming off in a rage.
Later Commodus is back in power and seemingly ready to sign a peace treaty with the Britons using the captured King and his daughter, the Briton King is willing to surrender to Rome and asks Commodus only that his people be treated fairly "as equals" - Commodus seems moved at first and shows off a dagger with the seal of Nero on it to the crowds as he speaks of the Emperor's will and the glory of Rome.
Then in what seems an act of good will Commodus offers the Briton King an embrace, although reluctant at first the Briton King does as he is asked for the sake of peace and even affords a strained smile (again, to try and appease Commodus) : only to be rewarded by Commodus viciously stabbing him repeatedly in full view of his daughter and people, spitting on the King and mocking his "peace".
Commodus then drops the King and speaks to the crowds, calling them "dogs" and declaring himself their new God - as he rants the King's daughter mourns over her father's corpse and the Roman soldiers have to struggle to protect Commodus from the enraged crowds, who start pelting him with stones.
Enraged Commodus decides to flee and orders his men to stay behind and put a stop to the rebellion, making sure to taunt the crowds as he fled under cover of heavy guards - promising to kill every man, woman and child for daring to defy him.
It is told that Commodus and his men stole a boat intended to help Romans escape "pushing women and children aside" to do so - this coupled with Commodus' utter contempt for life angers the soldiers sufficiently that they seek to return to Rome and argue Senate to have him punished (unfortunately this would prove futile as Nero and his two sons quickly turned Rome into a tyranny).
Later in the game Commodus becomes the target for Marius, now under the guise of Damocles, who hunts the murderous tyrant down to a Rome under seige by the three mad emperors and their Praetorian Guards.
It is revealed that Commodus took full credit for the defeat of the Britons and the capture of the King's daughter, ignoring Marius' and his men completely despite their sacrifices - this in combination with Commodus' countless other atrocities finally proves a fatal hubris and Marius (now Damocles) enters a gladiator arena in order to fight his way to Commodus, who (in a nod to his historical counterpart) fights and ultimately dies in the arena opposing Marius.