I quite like this one particular Star Wars theory that I have nicknamed the Snape Theory, which posits that Kylo is a double agent in very deep cover, trying to bring down the First Order, and Han’s death was pre-arranged and accepted by him at least (if not Leia) and that’ll be the Shock Twist of the next movie.
I dunno, I like it better than “Leia and Han’s son is very very evil for some not really specified reason.” Though I think it has SOME flaws…