Okay, whatever. I really should get my hands on the original play, if it's ever been translated into English.
A couple of postings back, I said you should try to learn something about the Guelfs and Ghibellines. I surrender on that. I did the research myself and read through the libretto a couple of times, at which point I realized that there is an allusion to "Guelfi" all of once.
You do need to know who hates who and why, though.
- The patricians hate Simon because the plebeians put him in office, and for 25 years he has been a ruthless ruler.
- Fiesco hates Simon because of Simon's involvement with his daughter Maria, which resulted in the birth of Amelia, and because Simon becomes Doge rather than Lorenzino, an ally of the Fieschi.
- Adorno hates Simon because Simon killed his father. He switches sides when he finds out Simon is Amelia's father, after nearly killing Simon twice (once in the Council Chamber scene, thinking Simon arranged Amelia's kidnapping, and once in Simon's apartments that night).
- Amelia hates Simon because he exiled her brothers.
- Lorenzino hates Simon because the plebians elected Simon Doge.
- Paolo hates Simon because Simon has denied him the hand of Amelia in marriage, after first agreeing to the marriage. This is after they've been allies for 25 years.
Sorry! I love this opera, but there are good reasons it's considered murky and confusing.