Commodus reigned for over twelve years, unlike the shorter period portrayed in the film. The character of Maximus had a similar career (and personality traits as documented by Herodian) to Claudius Pompeianus (a Syrian) who married Marcus Aurelius' daughter Lucilla following the death of Lucius Verus. It is believed Aurelius may have wanted Pompeianus to succeed him as Caesar in preference to Commodus but was turned down.
Aurelius
Pompeianus