Gladiator can't be relied on for historical accuracy. It invented a story about the son of the emperor Marcus Aurelius murdering his father because the emperor didn't want his son to be emperor. The truth is that Marcus Aurelius did want his son to be emperor and died of natural causes, wasn't murdered by anybody. Actually, the two of them ruled together until the father died.
What's true - in real life, Marcus Aurelius was one of the best Roman emperors, a philosopher and a good military leader, although his first attempts at beating the Germans failed. Apparently, he didn't do a very good job of raising his son Commodus. Historians say the problem with Commodus was that he was lazy, let things fall apart - the total opposite of his father.
There's a very famous book by Marcus Aurelius, The Meditations. He was really into Greek philosophers, especially the Stoics, and he wrote the book in Greek.
https://www.youtube.com/watch?v=yXcmkSqAqTI