Kylo Ren was neither Jedi nor Sith, but a dark side warrior with a mysterious past.
Kylo Ren was a product of both sides teachings. Son of Han Solo, and Once an apprentice of Luke Skywalker, he killed his fellow students and drove Luke Skywalker into exile, and becoming a First Order warlord and servant of Supreme Leader Snoke.
Kylo Ren was determined to destroy the last remnants of the Jedi, fulfilling the legacy of Darth Vader.
And while most would agree that Kylo Ren could never fill Darth Vader's boots, but he seems to be a suitable successor.
Kylo Ren's first appearance in the film is just epic. He is cold, Stoic, witty and extremely powerful. He
speaks with a robotic, yet silky voice, wields a wicked new lightsaber, and has prodigious control of the force.Usually villains’ appearance and stature match their powers (muscular build, rugged features represent strength, older villains represent control and mastery of their powers, slender build signifies speed and fighting prowess, larger/fatter build represents power and gluttony, grotesque face matches their inner ugliness, etc.), so it was off-putting to see the main villain’s intimidation factor plummet so hard.
Ren appeared young, which could have symbolized that he was still learning the force, impetuous, made rookie mistakes, and was at a crossroads on what side he would choose.