SPOILERS FOR STAR WARS: THE RISE OF SKYWALKER AHEAD
When Supreme Leader Snoke was first introduced in Star Wars: The Force Awakens, he seemed like a new omnipresence villain for the Star Wars universe but that idea was literally cut into pieces when Kylo Ren kills Snoke in Star Wars: The Last Jedi.
In Stars Wars: The Rise of Skywalker, it was revealed that Emperor Palpatine/Sith Eternal cultists created Snoke and was using his vast Dark Side powers to puppet him from Exegol, the Sith homeworld in the Unknown Regions.
Well, the visual dictionary companion book for the film via EntertainmentWeekly has added that moment was part Palpatine’s test for Kylo Ren, as he wanted Kylo to eventually kill and usurp Snoke’s position as Supreme Leader of The First Order.
The “Ren” in the “Knights of Ren” refers to another character named Ren (wasn’t seen in the movies) that is currently being explored in the comic book The Rise of Kylo Ren and the comic also explains that Snoke was influencing Ben Solo and he turned to him after destroying the Jedi Temple.
EW alludes that “the master” referred to by Ren in the comics might be Snoke aka Palpatine.
While the comics haven’t reached this particular point in Ben’s story, the Visual Dictionary mentions that Snoke promised Ben “powerful followers” if he proved himself worthy. There was a “grueling trial” of some kind, and Ben, taking the name Kylo Ren, succeeded and became leader of the Knights. Snoke, it would seem, was “the master” Ren mentioned in the comics.
Killing Snoke in The Last Jedi was the final test for Kylo Ren.
It’s made clear as early as the opening crawl that Darth Sidious (Ian McDiarmid) is alive, and has been for some time. Operating out of the Sith homeworld of Exegol, he, in addition to keeping himself alive through dark and mysterious ways, engineered Snoke himself to manipulate Ben, who at this point has been operating under the nom de guerre of Kylo Ren and leading the Knights of Ren for quite some time. According to the Visual Dictionary, Snoke’s entire purpose was meant to be a final test for Kylo Ren, testing the fallen Jedi on his ability to further the Sith legacy. The book also mentions that the Sith Eternal cultists, those who continued the efforts of Darth Sidious to form a new Empire, designed Snoke to act as “a final crucible” for Kylo to prove his power and cunning.
Snoke theories consumed fandom for years and when they weren’t fulfilled they sort of freaked out that he was killed off in The Last Jedi along with a bulk of those theories.
Filling gaps from the new movies seems to be the job of the comics and books, The Rise of Kylo Ren and the visual dictionary also shedding some light on The Knights of Ren.
That’s the problem with adding a high volume of characters in films of this scale, you can’t give everyone a backstory.