(This article contains some major spoilers for "Star Wars: The Rise of Skywalker")
The revelation that Emperor Palpatine would return in "Star Wars: The Rise of Skywalker" was definitely a big mystery of the type JJ Abrams loves -- we've all been cracking jokes about his whole mystery box concept since the "Lost" days. And this one was a doozie because, well, we've all thought for the past several decades that Palpatine definitely for sure died at the end of "Return of the Jedi."
And as we learned in the prequels, it was extremely Anakin Skywalker's destiny to kill him. So it was hard to guess how bringing the Emperor back would work, but it seemed like it would make the most sense for him to be a Force ghost who had been influencing events.
But from watching "The Rise of Skywalker," you're simply not going to get any answers about anything related to the Emperor. He's just there, with a gigantic fleet of Star Destroyers equipped with Death Star lasers, and you have to just accept it.
Fortunately, though, we finally get most of the key details from the novelization of "The Rise of Skywalker," which is dubbed the "Expanded Edition." While the novel certainly creates some new questions that may or may not be explored in the future, and also tries to recontextualize the entire film saga, it delves deep enough into what I'd describe as the "lore" of Palpatine that everything more of less makes sense now.
So the "Rise of Skywalker" novel recasts the Emperor's life story, and basically turns what he's trying to do in this movie -- pass his soul into the body of a person who has enough power in the Force to contain him -- as one of the main objectives of his entire life.
Obviously, one of the other objectives is to take over the galaxy. But ultimately his pursuit of power is endless. So he wants to rule, but beyond that he's trying to increase his power with the Force and live forever. A big detail that this book adds, then, is that back in "Return of the Jedi" the Emperor was trying to do to Luke what he was attempting to do to Rey in this film. So all that stuff where he was trying to bait Luke into attacking him was not just a ruse to turn him to the dark side -- he actually wanted Luke to kill him.
Now, I'm not convinced there's any way to read "Return of the Jedi" that way, but that's a discussion for another time. All that matters here is that these are the facts as we know them right now. But yes, that's a pretty major retcon.
What this means for how Palpatine survived when Darth Vader tossed him down that big pit in the middle of Death Star is that the Emperor came into that situation prepared to die and to pass his spirit into a new body. But obviously since his real plan didn't work out, he had to go to plan B.
And plan B was Exegol, home of the Sith Eternal -- you know, those creepy cultist guys from the movie. On Exegol they had been using Sith alchemy to construct a new body for the Emperor, but they were having a hard time making one that was strong enough to contain him -- presumably this is why he resorted to trying to steal other people's bodies.
So when Palpatine was thrown down that big shaft, just before his moment of death, he sent his spirit to Exegol, into the most complete body that his cultists had managed to put together. So what you're seeing in "The Rise of Skywalker" is either that clone body or another one built later. But since it wasn't up to snuff, his sheer power was rotting it from the inside.
This is, by the way, basically exactly the plot of the "Dark Empire" comics that were released 30 years ago. In those books, the Emperor put his spirit inside clone bodies that could not sustain him, and so he'd have to hop in a new one periodically. Eventually, he gave up and tried to posses Han and Leia's baby son instead.
Exegol isn't just the cultists, by the way. The "Rise of Skywalker" novel also gives a little bit more context about the place, specifying that they have a whole normal civilization there. As in, there were enough people living on Exegol to fully crew all those Star Destroyers, with each having a full complement of those red stormtroopers. The book says there are "tens of thousands" of those ships, and so we're talking over a billion people here, just for the military.So presumably there's a ton more on top of that, especially given the manpower that would have been required to build all those ships.
Obviously we see no signs of any civilization there in the movie aside from the big Sith temple and that arena filled with cultists. And that's because Exegol's cities are underground. We're not given any more details about them -- there's just a brief bit from the perspective of one of those Star Destroyer captains, who reflects for a moment on how she's living through the culmination of her entire civilization's history.
So that's all of it. Since you can't grow a human population that large that quickly, the implication here is that this Exegol civilization has been here a long time. Maybe we'll get more about it in the upcoming "High Republic" project, which will deliver many stories -- in novels and comics -- set a couple centuries prior to these movies.
But for now, Exegol remains a very mysterious place, just slightly less so than it was when all we knew about it was what we got from the movie version of "The Rise of Skywalker."