Warning: The following contains SPOILERS for Star Wars: The Last Jedi
After The Last Jedi, fans will probably know all the information the movies are going to reveal about each of these questions, with the bulk of the backstory (the Rey and Snoke reveals are fairly quick) going to Ben Solo, not only explaining his journey to becoming Kylo Ren but providing the backstory necessary to understanding the motivations behind one of The Last Jedi's biggest twists.
The most simple version, the version Luke initially tells Rey, is that he was impressed with his nephew's potential, seeing the "mighty Skywalker blood" in him. Taking Ben and a dozen other students, Luke started a brand new temple with the intent of training a new generation of Jedi. Unfortunately, Ben started to turn to the dark side. In a moment of fear, Luke considered killing him to prevent the rise of another Vader, going as far as to ignite his lightsaber while standing over his sleeping nephew. This simple act disgusted Luke and he immediately regretted his actions, changing his mind, but it was too late.
Ben saw his uncle's initial intent and attacked, knocking Luke unconscious, slaughtering his students, and fleeing with a handful of others in tow. That final detail making up the real origin story of the Knights of Ren.
Feeling absolutely crushed, not just by Ben's betrayal, but by the way his own involvement in encouraging his nephew's decent, Luke goes into exile, seeking out the very first Jedi temple. After arriving, Luke determines that the repeated failure of the Jedi throughout history, from allowing the rise of Darth Sidious and virtually pushing Anakin Skywalker into his arms to Luke pushing Ben Solo into the service of Supreme Leader Snoke. Feeling defeated, Luke determines that the Jedi Order will die with him, shutting himself off to the Force.
Meanwhile, having taken the name Kylo Ren, Ben's power only grows under the tutelage of Supreme Leader Snoke. Desiring to craft his new apprentice into the second coming of Darth Vader, Snoke seeks to sever all Kylo's ties to his former life and eliminate a division that still exists inside him. Snoke is a harsh master, but Kylo craves his affection. After his parents were mostly absent saving the galaxy or for some other reason and his uncle/master Luke was afraid of his potential, Snoke actually had a desire for Kylo to be as strong as possible, so the former Solo heeded his master's instruction, going so far as to kill his own father.
Unfortunately, killing Han Solo "split his spirit to the bone." Instead of giving him closure and purpose, it made him even more divided. When given the opportunity to also kill his mother, he takes his finger off the trigger. Sensing this division, Snoke creates a mental link between Rey and Kylo, convincing Rey there is a chance to bring Ben back to the light side, coaxing her out of hiding.
What Snoke didn't count on is that this bond would give Kylo a new connection to Rey, so when Snoke determines she must die, he sees another authority figure he can't rely on. As Snoke foresaw, this finally makes Kylo whole again and gives him purpose, but not in the way Snoke thought. Kylo once again resolves to abandon his master, killing him and giving Rey the classic Star Wars "rule the galaxy with me" speech, only to turn the might of the First Order against her and the remaining resistance when she rebuffs him.
Kylo's path forward isn't clear, but driven by seemingly pure rage and now holding the title of Supreme Commander of the First Order (or whatever's left of it) for himself, he's determined to wipe what remains of the resistance away before they manage to rally more allies to their cause.
We're bound to get some variety of books, comics, or maybe even animated stories of a young Ben Skywalker training in the ways of the Force under Jedi Master Luke Skywalker, but after the new backstory provided by the events in The Last Jedi, we now have a complete picture of what exactly caused Ben Solo to become Kylo Ren. Additional stories might flesh out the details, but when it comes to major reveals, The Last Jedi puts it all on the table.
Moving forward, the plot of Episode IX can, as Kylo would prefer, "let the past die" as it delves forward into the epic conclusion of the sequel trilogy, free from not only the pesky backstory and history of events since Return of the Jedi, but Star Wars history altogether. Chris Terrio and J.J. Abrams certainly have their work cut out for them. While they're free of many of the constraints Abrams faced kicking off this new era with The Force Awakens, they're also burdened by a number of new character arcs to resolve, including that of Leia Organa, which could be quite complicated after the tragic loss of Carrie Fisher.
- Solo: A Star Wars Story (2018) release date: May 25, 2018
- Star Wars 8/Star Wars: The Last Jedi (2017) release date: Dec 15, 2017
- Star Wars 9 / Star Wars: Episode IX (2019) release date: Dec 20, 2019