Good Storytelling
A highlight of this movie is the relationships Maximus has with 2 older mentors: Marcus Aurelius the Emperor, and Proximo the former gladiator and slave owner.
Each of these sage-like men give Maximus advice on how to aspire to be what they believe he’s capable of. At the beginning, Marcus pushes Maximus to follow Marcus’ wishes for Maximus to become emperor. He knows it’s Max’s destiny, pretty much, to become what Marcus once was: a great emperor for the Republic, one that would free the Romans.
Later on, in a parallel way, Proximo gives similar advice to Max, that Max can be the gladiator Proximo once was, and win his freedom from slavery.
And then we learn Proximo was granted his freedom by Marcus, and it just comes full circle! Good storytelling!