A/N: This may get rewritten later, but I had to write something after last night's ep. Any advice/suggestions/ideas are very welcome.
This is told from Micheletto's POV.
The people of Rome were whispering. Whispering about Cardinal Cesare Borgia, and the death of Juan Borgia. A few said that Cesare would never kill Juan for fear of their father. Micheletto wanted to scoff at that. But many said that Cesare had killed his bother – their 'disagreements' with each other were hardly secret – out of envy. Cain and Able – oldest story in The Book. Micheletto knew better. Oh, Cesare certainly envied Juan being a soldier; and having their father's approval and love no matter what he did, while it was denied to Cesare. But Cesare held that against their father, not his bother.
No, it hadn't been envy that caused Cesare to kill his brother. Cesare had told Juan that 'Borgias never forgive', and Juan had committed what Cesare considered the worst of sins, not once but thrice.
Juan's self-destruction threatened their entire family; but Cesare wouldn't have killed his brother for that alone. Cesare would just have worked to protect the family, and let Juan self destruct by himself.
Tonight Juan had endangered Cesare's Godson, their nephew; and his words to Lucrezia made it clear that as long as Juan lived, he was a threat to Giovanni. Cesare took his duties, including those as Godfather, seriously, and adored his nephew. Micheltto had been there when Cesare held his crying sister, as she related the conversation she'd had with Juan. Cesare had met his eyes over Lucrezia's head, and that's when Micheletto had known that Juan was a dead man.
Besides, Juan had once again committed the worst sin of all, at least in Cardinal Borgia's eyes – Juan had hurt Lucrezia. The only two times Cesare had killed in cold blood, had committed actual murder, had been for Lucrezia; had been men who'd hurt Lucrezia. The abusive bastard Sforza, and now Juan. Even the mistress's husband had been killed a fight. A fight Cesare had sought out, but still a fight. The man had been given a chance, unlike Sforza or Juan. Juan had gotten away with hurting Lucrezia twice, killing Djem and then Paolo. But he'd hurt Lucrezia a third time, and threatened Cesare's nephew and Godson. Cesare had taken no retribution the first two times because Juan was his brother; but those actions hadn't been forgiven. 'Borgia's never forgive.' And this time Juan had not only hurt Lucrezia, but endangered Giovanni, and signed his own death warrant.
As he'd told Cesare, Micheletto was impressed. Yes, he'd killed his own father, but he'd had no one to do it for him. Cesare could easily have ordered Micheletto to do it, then stayed away. No need to have his brother's blood on his hands. But Cesare hadn't done that; hadn't taken the easy way out. Cesare had killed Juan himself. It was yet one more thing about the Cardinal that Micheletto respected and admired.