My Roman Empire for a few days straight is how the actors of Commodus and Lucilla ( Joaquin Phoenix and Connie Nielsen) actualy came up with the one-sided incest dynamic.
Since Connie Nielsen ( a certicified history nerd <3) thought the character of Lucilla in the first script draft was unacceptable, as Lucilla was just depicted as a stereotypical "royal accessory" for Commodus, Connie was furious about this portrayal of Lucilla and critiqued it to Ridley.
Of course Ridley Scott did rely on the involvement of his actors to continue production, since the script was all over the place and it started with only 32 pages, the actors would get 4 pages of dialogue every single morning before shooting.
Eventualy Ridley gave Connie the green light to change dialogue, to make Lucilla appear more important,but also correct historical inaccuracies from dialogue.
Connie did realize in order for her changes to work, the villain also needs to be involved, so she approached Joaquin Phoenix on set. Joaquin, who was already batteling severe anxiety and impostor syndrome, agreed to collaborate with Connie and to rewrite the dynamic between the Imperial siblings.
The duo did recognise in order for Lucilla to be a more important character, Lucilla needed to be involved in a political intrigue against her brother, but also Commodus needed to be heavely attached to his sister.
The incestuous nuances came from the Roman history searches Connie did with the creative team between January 1999 and March 1999.
While the real Commodus was not noted to be involved with his sister Lucilla in a more romantic way, he did partake in incestuous relationships with his other sisters. So Connie and Joaquin used this fact to their advantage, to reshape the dynamic of their characters into a psychological chess game.
The incestous attachment towards Lucilla gave Lucilla a motive to conspire against her brother and to becomme the heroine a lot of viewers remember her to be, a character surviving in plain sight.
Also the character of Lucius was supposed to be a little side character, just a stand in at the Colloseum matches, but Connie and Joaquin did decide to use the character of Lucius as a drive for Lucilla to survive. But also a way Commodus tries to manipulate his sister into co-ersion.
They tried their best to protect Spencer Treat Clark from the psychological damage such on-screen dynamics could create. Connie, as a mother herself, took a more motherly and protective role towards Spencer, while Joaquin would always crack jokes in between takes and try to make Spencer laugh. While everyone else were batteling eachother on set and in the arena, all the three of them would just sit, eat snacks and enjoy the moment!
All those dynamics were writen in trailer sessions, as the two co-stars would lock themselfs in their trailers and work between lighting ajustments, breaks or even late into the night as shooting stopped for the day. These sessions would last between 3 to 4 hours, sometimes even untill late into the night and came on top of 14 hours of shooting evey day.
And these sessions went on for a few weeks,every day in April 1999, on time before the bigger scenes needed to be shot.
Of course in order for this psychological chess game to work and for this weird psychological torture to show itsself on screen, Joaquin would corner and touch Connie unexpectedly. The touching was consensual tough, and trough those trailer sessions Joaquin was familiar with the boundaries Connie has set.This aspect was a mutual agreement to show how invasive Commodus is, but also how cornered and trapped Lucilla feels.
Both of the actors were terribly exausted and this did help to signal how tired Commodus and Lucilla were, but also how the lack of sleep made Commodus more hostile.
