Star Wars: The Rise of Skywalker dropped the bombshell on us that Palpatine was the one behind the First Order all along, thanks to having secretly survived his apparent death in Return of the Jedi. Many fans found this hard to accept due to how it came out of nowhere, but if you pull all the pieces together, it’s possible to come up with a timeline of events that adds up and explains why the Emperor created this “contingency plan” in the first place. In short, it’s because of Darth Vader.
ScreenRant has shared a detailed, in-depth theory which attempts to map out how and why Palpatine aimed to extend both his own life and the existence of the Empire after his demise. Essentially, it’s all to do with a revelation hidden in Rae Carson’s Rise of Skywalker novelization. The book explains that Palpatine began to grow suspicious of his apprentice from the moment he learned about his son, Luke Skywalker.
Likewise, Chuck Wendig’s Aftermath: Empire’s End novel reveals that Palpatine became obsessed with exploring the Unknown Regions and with the origins of the Sith in his final days. It would make sense, then, that fearing Vader would turn against him, Darth Sidious began planning for both his own resurrection and to secretly rebuild his forces – the Final Order – on Exegol.
As for the method of his resurrection – possessing a clone body – SR suggests that Palpatine originally hoped to transfer his essence into Anakin Skywalker, before his predicted treachery necessitated a change of plan to the much less successful cloning idea. This would explain why his revivification was so flawed, with the villain forced to bide his time and manipulate events through others during the Sequel Trilogy.
The Final Order was prepared at speed, then, when the Emperor was nearing his end, while the eventual scheme was enacted by a much weakened Palpatine. No wonder it ended up being pretty easy for the Resistance to defeat him in Star Wars: The Rise of Skywalker.