Probably beaten to death...

I kinda wonder if the Sirens were incomplete.

The theory (a Siren theory!) starts with the name structure the three sirens have. It's an Italian musical term followed by something to do with light. Pretty simple.

Adagio is a slow and stately tempo, reflecting her cool and efficient leadership style and longer-term planning.

Aria and Sonata are musical opposites. An aria is a solo vocal performance without any instrumental accompaniment. A sonata is a group instrumental piece with no vocals. Is it any wonder each thought the other was the worst?

If the Sirens were inherently broken and imbalanced, that would be a good reason their music caused such discontent and why negative energy sustained them. The missing part would be Adagio's counter, and some basic Google-fu provides the terms allegro (fast, quickly, bright) and vivace (lively and fast). Of the two, Vivace seems better simply because none of the Siren's names start with the same letter, and Adagio and Allegro sound very similar (which could be its own comedy bit).

The second part of the name would need to be something to do with light and counter to the word 'dazzle'. Here I am not looking for an opposite, although blaze is a source of (growing) light while dusk is a time light fades. if Adagio dazzles people, Vivace should... shroud them. Both are means to blind someone. One does it with light, the other with darkness.

I think that this missing Siren idea means more, though. Adagio's Achilles heel is pride. Sonata may be a ditz and Aria may be always angry, but it is Adagio's well deserved pride that eventually leads to her defeat. Someone to counterbalance Adagio, reign her in, direct her energy or temper her ire just a little might have stabilized the group. It would also have given the group a clear second, and Adagio wouldn't have to make all the plans or keep the others in line as much, I think.

But I may be thinking this too deeply. It wouldn't be the first time.