Warning: There are MAJOR spoilers for Star Wars: The Rise Of Skywalker ahead. Seriously.
If Adam Driver's Kylo Ren wants to let the past die in Star Wars, then it makes sense that he's pretty pissed when the new movie starts: How the heck is Emperor Palpatine back in The Rise Of Skywalker? Darth Vader definitely killed him in Return of the Jedi... right? Yet here Ian McDiarmid's nefarious character is, up on the throne and cackling away yet again. Let's see if we can make sense of this twist.
The return of the Emperor, also known as Darth Sidious and previously known as Senator and then Supreme Chancellor Sheev Palpatine (yes, his given name really is Sheev) was teased in the first trailer for 2019's Rise of Skywalker. So fans have known for a few months that this was coming. While that may seem like a big reveal to give away in a trailer, it's not really that surprising in the grand scheme of Star Wars. Obi-Wan Kenobi's (Alec Guinness) death in A New Hope didn't prevent him from appearing as a Jedi Force Ghost in both The Empire Strikes Back and Return of the Jedi. Yoda (Frank Oz) also popped back up to have a full conversation with Luke (Mark Hamill) as a Force Ghost in The Last Jedi after he died. It's all very horcrux-y, to mingle Harry Potter lore with Star Wars, but since Palpatine's return is not fully explained, we're left to assume that somehow, Palpatine figured out a Dark Side equivalent to the Force Ghosts.
Here's what I can surmise from bits of information in The Rise of Skywalker: At the very beginning of the film, Kylo Ren arrives on a planet called Exegol where Palpatine has been rebuilding (but not really rebranding) himself ever since the Battle of Yavin at the end of Return of the Jedi. He also, apparently, created the gold-obsessed Supreme Leader Snoke (Andy Serkis) as a puppet-proxy — sure! There's a lab in Palpatine's lair with some Snoke clone parts in test tubes and a lot of weird machinery. Did he also clone himself? Did someone clone him? Unclear! Though it should be noted that in the expanded Star Wars universe (much of which has since been removed from the canon), Palpatine and cloning go together like Jedis and hooded robes, so, maybe.
The Emperor is barely functioning at the beginning of Rise of Skywalker, but later sucks Force energy from Rey (Daisy Ridley) and Ben at the end — just like the witches in Hocus Pocus or, also, Voldemort. He then becomes something resembling human again. The best explanation for how he could do this is... some Dark Side Sith trick that were technically warned about way back in 2005.
It all hinges on a scene in Star Wars: Episode III — Revenge of the Sith in which Palpatine takes Anakin (Hayden Christensen) to the opera and tells him a weird story about "the tragedy of Darth Plagueis the Wise." Plagueis was Palpatine's Sith master, who was somehow able to use the Dark Side of the Force to stop those he cared about from dying and — here's the kicker — create life himself. At the time, that was a sly way of explaining Anakin's supposedly immaculate conception (his mother explained "there was no father"), but now it also has to vaguely explain how ol' Sheev has returned to the land of the living. Palpatine may actually have had some kind of mastery over death. Unfortunately, the movie just doesn't explain how, so again, we must hunt for clues in the past films.
In Revenge of the Sith, Palpatine says that "the Dark Side of the Force is a pathway to many abilities, some considered to be unnatural" — emphasis on that final word. He repeats this line in The Rise of Skywalker. Now, did Palpatine share these unnatural abilities with Anakin Skywalker when his wife Padme (Natalie Portman) died of a broken heart? (Don't get us started on that whole thing.) He sure didn't, even though that's the whole reason Palpatine brought up Plagueis in the first place. Between Palpatine's self-resurrection and the discovery of Force healing, Anakin's ghost has got to be pretty ticked off that he was Vader-ing around when he could have raised Luke and Leia with Padme instead.
But, speaking of family ties, the bigger question raised in The Rise of Skywalker is when and how and who did Palpatine father a son with? And why did that child get to grow up normal and good-looking — never once tempted by the Dark Side or manipulated towards it? The story goes that Rey's father (Sheev's son) and mother resisted him and hid Rey away on Jakku. That's pretty compelling, but we don't learn anything further about them. So in effect, the fact that the Emperor fell into a void in the Death Star and miraculously brought himself back from the dead is now more probable than the fact that he had a normal son just walking around in the world. Seriously, how.
Apparently, though, as Maz Kanata would say, that's a story for another time.