I would strongly advise you not to think about how much sense it makes that kylo ren sees injuring himself as perfectly acceptable. like, he doesn’t argue when han tells him that snoke will throw him away, will destroy him, as soon as he’s outlived his usefulness. the script tells us he knows this, deep down. and he doesn’t rage against it – it appears to be something he accepted a while ago.
why is that? why is he willing to live with the knowledge that he is utterly expendable to the person on whom he has hinged his entire life?
well, let’s take a look back. we now know that ben solo felt abandoned as a child – that his parents split before he was sent away. and let’s not kid ourselves about whether he realized that at least part of the tension inherent in his parents’ marriage was due to him. ben was force sensitive from birth. this is a kid who would have been intimately aware people’s feelings of unease around him.
and what happens after his parents split, after his father leaves? he’s sent away. I think even a child who wasn’t force sensitive would be able to put two and two together. there’s something wrong with him. (he isn’t the child his parents deserve.) he’s got this great and terrible power and there’s this struggle inside himself that’s tearing at him day and night and he’s hardly old enough to understand any of it – other than that he scares even the people who love him enough that they send him away.
he’s wrecked his parents’ marriage – their lives – and inside his head is this voice, one only he hears, telling him that he’s right. he did. of course they sent him away – they don’t want him anymore. maybe they never even wanted him at all. confirming all his deepest fears and twisting reality and playing into the mental and emotional issues ben is already struggling with.
they don’t want him, this voice tells him, but there’s someone who does. him. snoke. snoke who takes an adolescent ben solo and tells him that he’s the only one who can understand him. that he’s special, his best and brightest pupil. his great weapon. this is literal child-grooming, as well as blatant manipulation of ben’s own non-existent sense of self-worth.
in his own mind, kylo ren has only ever been wanted as one thing: a weapon. a tool. that is the value snoke has ascribed to him, and it’s the only value kylo ren knows. and if your only worth is as a tool, well, tools are meant to be sharpened, aren’t they? honed in whatever ways their masters require. if kylo ren must drive his fist into his own wounds to intensify his power – his usefulness – well, it’s hardly a question at all as to whether he’ll do it.
his pain is the cost of his usefulness, and that usefulness is well worth the price. because make no mistake, for kylo ren, there is no worth as a person. he is a thing to be used.
…but even that is better than being not wanted at all.
What frightens me most about this is the idea that one point Ben may not have been able to distinguish between his own inner voice and Snoke. Snoke would probably have used this to mold Ben into what he wanted him to be. This would have caused a traumatic psychological break. There was literally nothing anyone could have done. Not Han, not Leia, not even Luke. This was something that was happening inside Ben, that only he could hear, and it was slowly twisting his mind against him. I think there’s a part of Kylo Ren that does know he’s been manipulated, but what difference does it make anymore? Its too late. Too late to make up for what he’s done, too late to go home, too late to ask for forgiveness. He has to believe that all his suffering has somehow had meaning, somehow been worth it, and that even a little of what Snoke has told him is true. Yet after he watches his father fall, and is not suddenly powerful with his own self-righteous anger, but weakened…he knows its all been a lie. He’s always been nothing but a tool, and so he might as well use himself as one. What difference does any of it make? Its too late.