Since J.J. Abrams and Lucasfilm are doing such a good job keeping The Rise of Skywalker details a secret, Star Wars fans have been spreading speculation and rumors like wildfire.
A new reference guide titled Ultimate Star Wars New Edition has shed some light on the Knights of Ren.
J.J. Abrams has said that the Knights of Ren do have a backstory, but it has not been revealed.
The Knights of Ren are not Sith and they are not tied to The Empire and Darth Vader.