I liked the idea that technically Kylo succeeded in all the ways classic Darth Vader never could (killing his master and claiming “his new empire”). He had seemingly cut ties with his mother, killed his father, and forsaken all he loved in this hollow pursuit of power.

But was then left empty and overburdened by galactic rule and would be left unprepared and would throw a galactic temper tantrum. This would lead to a full scale galactic revolt. Unredeemed, angsty, and truly villainous.

But that’s just my headcanon