There are many popular fan theories in the Star Wars universe, some far more outlandish than others. One Star Wars theory that still holds some weight among the fandom is whether the infamous Jar ...

The Stranger, a Sith Lord in The Acolyte ... It's easily adapted for Jar'Kai, which is why Form V is used by Ahsoka - whose two lightsabers feel like a light-side mirror of the Stranger's.