IMO, the backstory evolution is looking obvious AF - Last update 7/17
I agree with the popular Rey Palpatine theory 100% and have loved it since it appeared post-TFA.
My full prediction:
Rey is a hightened Palpatine clone, except he didnt want a female version. She was snuck into Luke's Jedi school to destroy it, but she was not falling into line with being all Palpatiney (her Dark Side was not natural as Palpatine wanted to believe perhaps), and Kylo was sent with his team to wipe it all out.
Kylo could not destroy Rey because he rightfully sees Palpatine, with Plagueis, as the "fathers" of Anakin, aka his great grandparents... This includes clones of Palpatine. He is loyal to the point where it becomes inconvenient to Palpatine.
Thus, Kylo did not kill her, and instead hid her on Jakku with suppressed memories.
Snoke was maybe a failed, or too-successful, overly powerful and uncontrollable Palpatine clone that was supposed to be destroyed perhaps, but was lost and went rogue outside the known system. Perhaps originally intended as a backup. Or also, perhaps he was 100% working properly as a backup, and his gnarled appearance made him look completely different from his genetic source of Palpatine.
Palpatine in ROTJ was itself a remotely operated clone, controlled in a way that is similar to Kylos connection w Rey in the last movie. And WHO connected Rey to Kylo? Snoke. The power Palpatine uses to control his clones may depend on them being clones, being the same genetic material he is, so thus Snoke AND Rey can both do that, can both control from afar, as they are both Palpatine's genetic material. Together, Snoke can force Rey's inherent power to connect to Kylo, and capture his mind, but only to speak, not to control him. REY is the one being controlled and forced to connect.... Because REY, Palpatine genetics, is being controlled by Snoke, just like Palpatine controlling a clone puppet style.
Maybe Snoke is rogue because he can do this as well as Palpatine can, so Palpatine can't control him. That's why Snoke has power over Rey and why he knows who Rey is from the START.
This is solid stuff, and even the Snoke as Clone element is not my idea, I just included it all in a cohesive theory.
AAAAND what does Luke do in Last Jedi? Remote Presence. Just like Palpatine with a clone, but Luke needs no clone and is not using it to control! He was using the LIGHT SIDE version of the same power that Sidious/Palpatine is using on the Dark Side in this theory!!! How cohesive is that?
Here, at the end, we will finally meet the original, still living Sheev Palpatine aka Darth Sidious. Probably Ian McDiarmid again with no makeup just like in the prequels.
Clone strategy is his version of Plagueis' immortality ideal.
7/17/19 (actually first posted this yesterday the 16th):
Lastly, the title: Rise of Skywalker.
What brought about the rise of the Skywalkers?
Palpatine aka Sidious. (Plus Plagueis... would love to see him show up suddenly!)
Calling this entire setup right now.