i

i totally agree like a couple weeks ago you thought she was dead and now you find out shes alive and in a whole bunch of shit. Like i would also want to take her away and protect her if shes getting into some unnecessary stuff. Its normal he doesn't like the grand duke because he doesn't know him or his intentions. And its not like hes refusing to help them hes just trying to take the safest rout for her.

Exactly. I think the author did a good job with Jean's characterization in order to justify his distrust: in the past, he and Adele got screwed by "friends" they trusted, but those so called those "friends" ended up selling Adele and covering it up. So Jean has experience with "friends" suddenly turning traitors and changing sides. Moreover, if he think those "friends" betrayed him and Adele also out of hunger and desperation, then it's reasonable for him to expect that the black haired guy's own desperate situation (with his sickness, the physical impediment that allegedly doesn't help him to fight properly, and the emperor's constant surveillance over him), could all easily lead to a similar end (of the black haired guy also coming to betray them, out of desperation).

So, the author cleverly gave us a backstory so we can see Jean's side, and if we dig a bit we can see how this character would react to the perpection of any parallels between that instance of betrayal in the past, and the current present-day situation.. That's why Jean wants to put to test just how high the black-black haired duke's level of desperation can become, by testing the duke's physical state, along with the depth of his real feelings for the mc... Oh, Jean is definitely jealous here, etc etc, but he's not just some dude acting out a fit of jealousy, but an underworld who's carefully gauging the risks of a transaction. He's obviously gonna let go of this once the duke proves he's worth the risks, but until then, Jean will proceed with him like the picky underworld boss who by default handles new risky business and new "risky" people with a healthy dose of skepticism. Moreover, his dislike is not hard to understand when the ML is a noble from a different class (a class that has never done much good for commoners like Jean and Adele), and one who's allegedly so close to the emperor that it'd be much less trouble for him to sell both Adele and Jean out to him, rather than to oppose him...