the trope hinders that relationship insteads of helps it, it dosent matter what raphs feelings are or how much she loves or hates him because he always has control over her. if she dosent want to do something, she can be forced to do so. its a contrivance used to futher power fantasies in fantasy mangas.
the entire relationship could be done without a magic slave crest that can automaticlly be used to control someones every actions under threat of excruciating pain. the cave scene where naofumi allows raph to run if she wanted, but she chooses to fight for him, that scene is hindered by the fact that she has a magic slave button. the choice for her has always been an illusion.
In that cave incident, Naofumi
tells her to run after seeing her hesitation. The character moment has significance precisely because Raphtalia refuses to run and comes to an understanding that she should fight to prevent others she cares about from being killed.
And why are you talking like you skipped the Spirit Tortoise arc on top of skipping me talking about Raphtalia's slave crest being broken? Did you also gloss over Raphtalia choosing to have her slave crest reaffixed after the duel with the Spear Hero, only for it to never be used until she became a Vassal Weapon wielder and thereafter
couldn't have a slave crest?
the story also uses it as narrative crutch, unless they cannot explicitly have a slave crest then any one without one cannot truly be trusted.
That's not a detail generally used, and it's actively undermined in
this chapter through the introduction of the detail that slave crests can be of an inferior quality that doesn't prevent someone like, say, Sardina, from beating up her master.
suddenly slapping one on removes the element of gaining any amount of trust
When Rishia had one affixed to her, the
sole reason was to allow her to gain EXP bonuses through allying with Naofumi. "Trust" wasn't ever brought up. It was also never brought up in affixing them to the Seatto children later on.
Meanwhile, the soldiers he registered as party members after the second wave were never given a slave crest. The blacksmith was never given a slave crest. None of the people in the town he helped by disposing of the dragon's corpse were given a slave crest. None of the people in the town he helped by destroying the invasive plant were given a slave crest. Nobody spotting the mount race was given a slave crest (and Naofumi nearly got screwed because of it).
It never even came up.
Fitoria was never given a slave crest (not that she could have been)-- and speaking of which, it was because of Fitoria that he even resolved to attempt to work with the other Cardinal Heroes at all. I already mentioned Raphtalia.
This was also a non-factor in learning to trust the other world's heroes (since they also can't be enslaved).
The entire point of those instances was to test how he'd navigate brokering contracts and relationships with others after realizing how easily one can be brutally betrayed, while also emphasizing his intrinsic good nature by showing that he's willing to stick his neck out to help and ally with people even if he's going to be a hardass about it up to that point.
In Raphtalia's case, it was
systematically engineered to showcase that her loyalty to Naofumi is intrinsic and uncoerced. No, seriously, think of the all new writing (read: romantic developments) that's now fully possible because Raphtalia is physically incapable of being enslaved.
naofumi will never have to work on his trust if everyone around him has a magic mark that suddenly makes it impossible to disobey him, he will never have his vulnerability challanged if their is never a chance for betrayel. he explicitly never trusted the other heros,
The other Cardinal Heroes also never gave him a reason to trust them. They didn't start off on his side because they believed he was a rapist on account of the kangaroo court he was subjected to.
he only trusted the queen after seeing her nearly kill her daughter in what was essentially his name.
I don't know what point you're trying to make. He never
had a reason to trust the thitherto clandestine queen after the way he was treated by Malty and Aultcray. He was so much in a position of ignorance up to that point that he didn't even recognize that Melromarc's regents were queens rather than kings. Why
would he trust her without her doing something to get him to trust her (that he could concretely attribute to her, anyways)?
And whose fault was it that Malty is such a pathological liar that she
had to have a slave crest in order to tell any kind of truth, and still nearly killed herself telling lies? Or, should she just have not been written as a pathological liar that has to be coerced into telling the truth?
You're writing as if Naofumi's character arc along these lines is to become as gullible as he was when he was summoned, or as if that'd be a good thing.