When first meeting Kylo Ren, we hear the music of the First Order build up in anticipation as his ship makes its way down to the village. As he exits the ship and makes his way down its ramp through the blow off smoke of the door, he makes his way towards Lor San Tekka. This is the first hint we get at Ren having some form of emotional tie to the light side of the force. Lor San Tekka states that the First Order rose from the Dark Side, and that Ren does not come from the dark side. He says that he cannot deny the truth that is his family, giving us the idea that it is possibly in relation to someone who was or is a Jedi. So straight off the bat in this film we see a hole, or weakness if you will, in Kylo Ren's evil conquest. He does not let Lor San Tekka finish his thought about Ren's family, but strikes him down with his three prong, sword-like light saber.
Ren has something to hide deep in his emotions that he does not want anyone to find out, making him have a weak point. We later find out that his parents are none other than Han Solo and Princess Leia. Leia is one with the force, although she does not physically use the force as others who are one with the force do, she comes from a family that is strong with the force and chooses to become a general and not a Jedi. This gives Ren the ability to use to force because it is in his genes, but obviously, he takes his force and trains hard to become a Sith and use his powers for evil instead of good.
Kylo Ren Shows His Emotions and Anger Easily
It is easy to say that Ren shows his emotions easily, as we have viewed him throw multiple temper tantrums when things do not go his way. Fortunately enough for the Jedi, and the film, things seem to not go his way more than they go in his favor. He has plenty of power and strength, but he does not know how to control it. The Sith Lord which we have seen the most of is Darth Vader, and he knew exactly how he should control his anger and emotion. Vader had some help along the way due to having his mentor giving him orders. Emperor Palpatine served as a Sith Lord for the dark side and stole Anakin Skywalker from the Jedi's and took him under his wing as his apprentice. Kylo Ren was said to be originally trained by his uncle, Luke Skywalker, but Kylo was driven to the dark side and to become a part of the Knights of Ren by Supreme Leader Snoke.
The main difference here for each apprentice is that Vader was close with his mentor, being able to work with him personally, while Ren has worked with the mere illusion of Snoke. Each time that Supreme Leader Snoke appears in a scene, he is a hologram that disappears once he has completed speaking with whomever it is he has to give direction to. This creates an emotional disconnect between apprentice and mentor. Another huge scene that shows that Kylo Ren cannot become the most powerful Sith Lord is when Snoke asks for Ren to be brought to him so that he can complete his training. How is Kylo Ren to become the most powerful Sith Lord as he wishes to if he has not even finished his training on the dark side of the force? Maybe this final step in his training is learning how to control his force abilities and not take them out on his own ship when his plans are foiled.
Kylo Ren Shows His Face too Often
Another emotional factor that deals with those that Kylo Ren faces, is that he does not emit enough fear. Darth Vader was feared by all who crossed his path, and while Ren is still a powerful being, when coming face to face with opponents and those in his way, they do not tremble in fear as much as they did with Vader. Part of this has to do with the mysterious demeanor of Vader. It was well known that Vader was once Jedi Knight Anakin Skywalker, and that he is part man and part metal due to the injuries he sustained. I do not know about you, but I would not mess with a man who is half robot that is known to be the strongest user of the dark side of the force. Due to Vader's physical appearance, and the fact that he need the helmet to breath, he never shows his face until he is unmasked at the end of the saga. Ren willingly removes his mask at multiple points of the film, giving a face to the evil villain. No offense to Adam Driver, aka Kylo Ren, but while he is not the greatest looking man, he is also not the scariest of faces that we have seen throughout the Star Wars saga.
His Physical Force Abilities are Strong, but are His Mental?
A pivotal moment in Star Wars: The Force Awakens is when Rey is captured and locked up by Kylo Ren. When Ren enters the room and attempts to interrogate Rey, well he does just that, attempts. Rey resists from the mental force tricks that Ren is trying to use on her. Ren has too much of an emotional block due to the fact that he knows he may never be as strong and powerful as Darth Vader once was. After killing his father Han Solo and not being able to please Supreme Leader Snoke, there is a lot on Ren's mind for what he has to do and what he has already done wrong. So much on his mind that he, one who has been with training in the dark side of the force for years, cannot even read the thoughts of Rey, who has not learned about possibly being able to use the force on her own until recently.
Kylo Ren is TOO Emotional
Darth Vader would get direction from his mentor and follow them down to every last detail. Kylo Ren had many slip ups in the evil plots that Supreme Leader Snoke was instructing him to proceed with. Physically he had what it took to stop those in his way, but mentally he was unstable. Now, being unstable is not particularly a bad characteristic for someone on the dark side, but how unstable is too unstable? With multiple emotional blocks that Kylo Ren has to deal with, it seems that he is indeed far too emotional to become the most powerful Sith Lord.