My boyfriend seems to have Stockholm syndrome

I'm 23 y.o. man, and for the sake of anonymity, I'll call myself K., and my boyfriend is S. So, I met him a couple of months ago because he became something of an intern at my work, and I'm responsible for him. He's not officially an employee yet, but my boss said, "Since you brought him here, you're responsible for him." So now this guy is my assistant (and boyfriend) and follows me everywhere like a puppy.

But over these months with him, I've noticed some oddities in his behavior:

• Firstly, he's always very quiet and never speaks first, as if waiting for permission. If you want him to say something, you have to ask a question that will lead him to that answer. • Secondly, at first, his passivity irritated me, but soon I warmed to him. He's younger than me, so eventually I began to find him charming and the way he runs after me, as if he can't live without me by his side.

• Thirdly, he never says if he's sick or in pain, which worries me. Sometimes he looks very pale, and I have to coax words out of him about what's wrong; like, sometimes he gets nosebleeds and I think he's anemic because of how pale he looks.

• And fourthly, he is a total masochist....

That's where the weirdest part begins: he acts dependent. We quickly got to sex. I think we had it before I developed feelings for him, but I think he already loved me at that point. I'll say right away that I prefer the bottom role, but it turns out he's also a bottom one, so I had to change my role for him, although I don't really like being a top.

During sex, he often asks me to choke him. He also likes dirty sex without a condom (sweat, drool, sperm, blood all at once, more better). I like clean sex with a condom and don't like violence. I don't want to choke him, but I can't refuse when he asks me with puppy eyes. One day he asked me to pee in his mouth, which shocked and embarrassed me at the same time, because where did such an idea come from in his innocent head? I refused, of course.

He also gets turned on by the sight of blood and has a lot of scars on his body (between his legs, arms, neck, and back). He also has a huge tattoo on his back. When I asked him about the tattoo, he told me about his ex, who groomed him since childhood, since they grew up together. It was he who gave him the tattoo and left the scars. I'll call this guy H., but to put it briefly, he didn't treat S. very well, and then committed suicide, and now S. feels guilty. S. says he doesn't remember much and is twisting the facts to protect H. He doesn't see that H. was the problem and thinks the problem is him. But as an adult, I can appreciate that he was most likely simply used. S. said that H. liked to choke him and cut his skin during sex; that's the little he remembers. I think he was so traumatized at that moment and shocked by the pain that his psyche decided to protect him and find pleasure in it.

Now he can't live without humiliation and violence against himself. Personally, I'm not against BDSM, but I'm not a sadist. I feel like his desire for violence isn't genuine, but forced, meaning that if I indulge his desires and stifle him, I'll be no better than H. At the same time, I genuinely like him; he's sweet and has managed to remain innocence despite his trauma, like the purest of first snow. I'd like to help him somehow, but I don't know how. I think it offends him when I don't want to do something "pleasant" for him (like pee in his mouth), but we have different ideas about what "pleasant" is. I just want to gently explain to him that what he's asking for is wrong and that he's been forcibly corrupted.