The more and more I think about, go back re-watch, re-read my TFA materials, listen to spoilers, listen to AD talk about Kylo's "humanity" in ep8, the more I'm convinced Ben Solo's story is a tragedy and we must truly feel pity for him. I've posted many times comparing Kylo to classic Greek and Shakespearean tragedies and called him a tragic hero. I still stand by that. If we can buy Anakin's redemption than you should acknowledge the potential for Ben's redemption.
Before everyone starts running their "but he killed his dad, LST, Luke's padawans, etc.", consider every amount of evil Ben (choosing my words carefully) has done was a test. Not only for Snoke, but to prove to his grandfather he's worthy of the black mask. He keeps having to prove himself. Over and over. He kills Luke's padawans. He kills LST. But then has a feeling of "the pull to the light?" Dude has been on a murderous rampage the past 5-6 years but he still can't shed the light? Yep, because in true wannabe fashion, he can't fully commit. That is why he may never be a sith. He cannot will himself to hate. He has to manufacture it (see the symbolism of punching his wound prior to the saber battle). Kylo can't completely go over to the dark side but it has "already dominated his destiny." He's in a cycle he can't break out of. Leia knows it. I believe Rey knows it now too. Look at Kylo's face each time Rey's bested him, whether interrogation or by saber. He looks stunned, almost pathetic. Perhaps Rey makes him realize he "will never win." He never will be Darth Vader. He can barely even be Kylo Ren.
I am far-reaching the TFA novelization and I think I finally got what I'm supposed to get out of Leia and Han's talk about Ben and Snoke. I get the feeling Ben was never a kid with mental issues. He was simply bored and lonely. He had two busy parents and was left to his own. Thus, Snoke knowing a Skywalker descendant had the equal potential for good or evil (Luke/Leia or Vader), began to work on Ben. We don't know if it was mentally (Obi-Wan style - see Luke and Rey) or physically (befriending him somehow -see Palpatine Playbook). But Snoke influenced Ben long before he became Kylo. When Leia tells Han of Snoke's influence, Han asks, "from the beginning?" I found this intriguing. The beginning of what? Ben's life? Ben's personality changes? Ben's turn to the dark side? Leia says she didn't tell Han for fear he'd push him further. So my guess is it was a combination of all those things. Leia believes any evil Ben committed was because of Snoke. She feels he's acting the part of Kylo Ren. Like most of us, when Leia says she wants Ben back, I thought it was odd. Yes, I know he's her son, no stronger love than that of a parent, yada... But she senses his conflict. There's still time to bring him back. Yet, Leia "has a feeling" it must come from Han. She was right!! We all saw it. Kylo kills Han Solo and it doesn't make him feel any better. He passed Snoke's test but he didn't pass his own. He will not be Darth Vader. No matter how much he surrounds himself in his grandfather's paraphernalia (helmet, alleged cape...), he will never shed Ben Solo. Just as Vader could not shed Anakin Skywalker. "You can't deny your family." It's an ironic lesson that makes for a great story. The Skywalker lineage DOES have equal potential for good/light or evil/dark. It's the choices the individual makes that determines their true destiny.
That being said, Ben will keep spiraling, go darker and darker in deeds until he realizes the truth and accepts his fate. Very much like Macbeth
