The Knights of Ren were set to play a big role in the new Star Wars trilogy when their history was laid out in The Force Awakens by director J.J. Abrams, but the payoff never arrived. The Last Jedi director Rian Johnson decided to scrap the storyline entirely because he believed the movie was already too bloated, to the great disappointment of fans. It did a great disservice to the Knights and a new fan theory rights the wrong presenting a scenario that would see them return in Episode IX and take on their master, Kylo Ren.
The theory, presented by a Reddit user, sees J.J. Abrams re-incorporate the Knights of Ren in Episode IX using the events of The Last Jedi. It starts right off the bat to make up for their absence in the last movie. Speaking theoretically, Kylo Ren sent them off on an assignment, but now they are back and are very angry at Kylo for killing their leader, Supreme Leader Snoke.
Aside from that, another major reason for their separation from Kylo Ren is his continued exploration of the dark side. As Kylo went darker, the Knights chose to stay closer to the light side, thereby making them sort of Grey Jedi, combining uses of both the light and dark side.
At this point, Rey is off on a mission to find more hands for the Resistance when she stumbles upon the Knights of Ren. They extend an off to her to join them, which she finds appealing as they are now Grey Jedi, and together they join forces to take down Kylo Ren and the First Order.
This task will be made much easier as Kylo Ren and General Hux have come at odds with one another, each seeking full control of the First Order. This separation of power leaves them susceptible to an attack, which Rey, the Knights of Ren and the Resistance enact, toppling the First Order for good.
It’s quite an interesting theory, but that’s all it is right now, just a theory. Take it with a grain of salt as neither Disney or Lucasfilm have confirmed any of the plot points happening in Star Wars Episode IX. As has been customary with past Star Wars movies, details are being held close to the chest and we won’t learn anything at least until the first trailer drops, which might not come until next summer.
But tossing the idea of J.J. Abrams bringing back one of his biggest teases in The Force Awakens with Knights of Ren makes too much sense to ignore. It’d be a great way to explore Kylo Ren’s past and further examine how he abandoned his family, another element Abrams took great care in touching upon with the death of Han Solo.