I think they had an interesting story that didn't have enough light shed upon it. have a few unanswered questions that maybe a few people have theories about (or if I missed something, I know there is an ATE I missed about them)

1. What exactly was meltegemini? A poison element eidolon that was fractured in two somehow? This would explain thier connections with the eidolons (extraction)

2. And why were Zorn and Thorn the only ones that could extract eidolons, did kuja know this and introduce them to the queen? I doubt this since they made it seem like they were around for a while (everyone being so used to thier presence) and the queen definitely didn't take them in because they had that power, because she was only recently interested in power/greed etc.

3. Were they cursed with some sort of virus? they give hints about this through the hold thing ("the queen's backing," medicine perhaps) and ("now you too have the virus")

Either way, I still like Zorn and Thorn, their theme song rocks.

well there really seems to be two possibilities...

1. Meltigemini was a creature from Terra that was able to split into two and disquise itself as two Jesters

2. Zorn ad Thorn were originally just the Jesters of Alexandria, and when Queen Brahne started dealing with Kuja, he found a use for them, and using similair techniques as he used to make the Black Mages, turned them into creatures that could meld into one.

Problem is...neither of those theories explain how they know the extraction ceremony.

They just can. Vivi can learn new spells from weapons so maybe the jesters could learn things from Kuja because Kuja just couldn't be arsed to do it himself.