To those who create engaging RP solutions, from all of us who will eventually find you and have our Sindome experience enriched, please don't stop.
Here is my take, and some constructive criticism for both sides.
Before engaging in any torture whatsoever, definitely pause and ask, "Hey, this is about to get real torturey. You down with that or should we close the curtain for a fade to black."
This has the obvious effect of displaying kindness to the player, of course, but other effects as well. It separates murderhobo from Vera for the other player. (sorry Vera, just using you as an example). When the torturer and the player are more clearly separated, it reinforces the narrative that you two players are cooperating for a story, even if one character is 'winning' and the other is 'losing', per se.
The most important thing (after kindness) is how this will help a player with a victimized char progress from one state into another. No-selling is, from what I can see, Denial. Not rich RP with nuance yet defiance, but straight denial. If the player finds themselves in Denial and doesn't process that or even realize it, their char can't move past it.
Now for those involved in torture RP. As a way to get the most out your time, and IMHO have the best time getting tortured, I suggest dipping heavily into Kubler-Ross's five stages of grief. Maybe as a player you're experiencing them too? Let's take a look.
Duke Puke says, oocly: "Torture upcoming, wanna RP through this or prefer FTB?"
.oO(Oh shit. Okay, check all the exits, flee, flee, nope, got a signal? no? this is totally unfair, dammit. This can't be happening.)
DENIAL!! (Not just declaring something as untrue, but the refusal of something requested, whether it's realistic and fun RP, or an IC secret)
Newbert says, oocly: "Cool, whatever, let's rock and roll, boyo."
Duke Puke sets his medical tray down, telling Newbert, "You vill tell us your mona's progia number, von't you?"
RPing denial can be varied and nuanced, dull and obvious, or even crazy fun.
Newbert snorts, "Can't hurt me, baka, I've seen lit'ly e'rythin' ever. Eat a bullet, rimrag."
Newbert shouts, "I EAT PAIN FOR BREAKFAST!"
Newbert thrashes around in chair, straining futilely against his bonds, shouts for help, and keeps shaking his head, muttering, "This can't be happening."
ANGER (If you're angry at the player, maybe that's natural, but not conducive to great RP. Take a breath, relax, play your char as is, not as is ideal. Anger IC can be a blast though. Channel that.)
Duke Puke smashes all three of Newbert's phone's on the ground, laughing maniacally, before telling him, "I have made three wonderful Sicads about you, with so many puns in them!"
Newbert says, rolling his eyes, "Just kill me baka, can't get nothin' off me."
Newbert glares angrily at his broken phone chunks, "One of those was an Eleven! And why is your accent so inconsistent!?" Newbert tries to kick at Duke Puke, "When I vat up, we're gonna find you, and destroy you, somehow."
BARGAINING (Okay, so maybe you don't want details about your bone sounds, the color of viscera, or some weird, twisted semi-creepy stuff. Bargain. As in asking OOCly, "Can we fade the Gore but keep the dialog? Or maybe we could get some xhelp to weigh in on if I could stand X or Y with these boss stats and prior experience?" Always a good go to ICly, too. Mona's # is precious, maybe some cash will settle this?)
Duke Puke removes a brown-spotted, bulbous pear from his medical tray, three blind nice, and a marker, "Prepare for utter agony, Newbert B. Trippen."
Duke Puke proceeds to vividly describe how his High School dance should have played out if God were fair, with detailed monologue, using nice and Mr. Pearface as props.
Newbert says, "Pfffft. Did you hear me? I said PFFFT. That's twice now."
Newbert begs and pleads, offering various reasons why Jennifer might have just not noticed Duke Puke, or maybe Capt. Jock is a nice guy if you get to know him. "What about my locker code, fool? I got fifty stacks in dere. I'll give ya that, you let me go. Chill, yes?"
DEPRESSION (So maybe your newbert is gonna die. It's not to a rat! Or a dog! And all your custom gear and loot is going to a PC! Not an NPC. It may have taken a long time to get your things, but it truly could have been worse.)
Duke Puke cries with his face in Newbert's lap, looking up at him with malevolent eyes, "We were in Loooooove!"
Newbert sighs, "Just kill me dude."
Newbert groans in utter frustration, tilting his sweat-beaded head back to exclaim in a raspy, desperate voice, "Duuuuude, please just fucking kill me. Please! This tangent is clearly not worth the effort and has some serious flaws you'll only notice long after committing to it!"
ACCEPTANCE (Maybe, if you don't get the result you want from your RP partner, you just have to accept they either do not RP this well, your reward shouldn't be hung up on them, or you haven't gone full Sindome cyberpunk torture to the max. Alternatively, victims, sometimes shit sucks. When you finally do get yours, and you're the badass walking down X street, how do you want your victims to react to your RP when the situation is flipped? Give a penny, take a penny. Torture it forward. That kind of stuff.)
Duke Puke wields his corpsteel katana, telling Newbert, "Now that I've wasted enough time, my accomplices are in place, and I can begin phase two."
Newbert hangs his head in acceptance, jerking it up to ask, "Wait, what?" Before the katana falls.
Pukeface Jones hands Newbert a pear, a phone, and a pair of pants, explaining, "Quick, call yer Mona. Duke Puke has flipped on everyone. we need your help taking him down. Everyone's help."
I hope this had been genuinely productive and helpful and not an unnecessary waste of everyone's time. At the very least, amusing. Delete if just in poor taste. No-selling hurts the person no-selling most, by eliminating their role-play options, the game's quality, and their next sleeve's lifespan.