Alex:
I suppose it makes sense that after everything that had happened, in the end Cesare was finally ready to fully commit to his feelings for Lucrezia and their relationship, I also think it's very likely that by the end Cesare was convinced that he was the only person who could truly protect Lu, because it's true that he didn't really trust anyone else towards the end of the series (especially Alfonso when it came to Lu's safety), except for Lu of course, she was the only person in the world whom Cesare fully and wholeheartedly trusted. So after thinking about the finale more, Cesare's possessiveness towards Lu in the end is starting to make more sense to me now
And I definitely think that if Showtime had commissioned a S4, the events that would've transpired in S4 would've been very different to what was depicted in Jordan's book...especially regarding the siblings' incestuous relationship and Lu's character development. Jordan completely destroyed the integrity of Lu's character by having her poison both her father and Cesare in the book, ultimately murdering her own father and attempted to murder Cesare whom she's suppose to love very much. I think the production crew and the casts of the Showtime version probably would've strongly opposed of such nonsense to play out in S4, especially Francois and Holliday, I can just imagine them both arguing with Jordan over this, afterall they did argue with Jordan quite a few times about the incest during filming lol
And I also think Jeremy Irons probably would've disapproved of such atrocious storyline too, he probably wouldn't have wanted his character Rodrigo to be killed by his own daughter. There's just so many problems and inconsistencies with Jordan's book that I think much of what was written in his book would've most likely been scrapped if they had made a S4.
And like I mentioned before, Lucrezia's reaction when Cesare became possessive of her in the end was quite positive...I mean, instead of pushing him away in disgust or ignoring him, Lu actually cocked her head like she
approved of Cesare's sudden declaration of his possessive love for her, and she looked like she was
enjoying the moment as Cesare affectionately buried his face in her chest as she lay on the bed. That kind of receptive response from Lu certainly suggests to me that the siblings would've had a much more positive and happier outcome in S4 compared to what happened to them in the book, this is further compounded by my belief that the casts probably would've opposed of the atrocious writing in Jordan's book. I agree I think the siblings would've most likely continued with their forbidden incestuous relationship secretly, even after Lu eventually marry Alfonso d'Este the Duke of Ferrara. As you mentioned, even in real-life, the real Lucrezia's marriage to Alfonso of Ferrara also seemed to be another loveless marriage because even despite her marriage to the Duke of Ferrara being by far her longest marriage lasting till her death and their marriage produced many children, but neither spouses were faithful to each other, they both had extramarital affairs while they were married to each other, especially Lu who had many lovers while she was married to Alfonso of Ferrara. So I think this issue probably would've been addressed in the potential S4...I don't know if Lu would've had other lovers during her future third marriage, but Cesare definitely would've been one of Lu's main lovers, if not her ONLY true lover during her 3rd marriage, I can definitely imagine that happening in the potential S4
I'm not 100% sure what the exact storylines and events that the writers would've explored in the potential S4, but the incestuous relationship between Ceasre & Lu definitely would've continued to be 1 of the most important storylines in S4, since their incestuous relationship became 1 of the most crucial and most popular plotlines in the entire series