"No, you can't understand." Jesper is rarely sharp with people, but he is now, and he doesn't mean to be a prick about it, but he's tense at the moment. "Where I'm from, being born a Grisha means four things can happen to you. You die, either by using your powers, like my mother, or you're murdered by the Fjerdans, an entire country hunting us down. There are plenty of people willing to sell you to them for a nice price too." It's a product of being in this place that he can talk about his abilities and about his mother, who was a subject of silence for a long time.

"Or you get taken to the Ravkan army, where you have no choice but to fight for people, some who wouldn't mind joining in the mass slaughter due to sheer prejudice, but have been convinced we're worth keeping alive to be fodder." The thing is that Nina loves Ravka, he knows that because she's argued with him about this before, and she wasn't terribly happy about him hiding his abilities from her. But he would assume anyone raised to be a proud and loyal soldier would feel that way.

"Or you get used for your abilities, sometimes by being captured, sometimes by willingly selling it but with always the threat hanging over of the rest. Or you hide, like I did, which is difficult because not using them makes you sick, not always in obvious ways." Like his addictions and some of his other mental issues, since his health was high but the damage was done elsewhere. He explains all of this very flatly and directly, laying out a lifetime of fear and avoidance that frames being a loose Grisha.

"That has been my life. Maybe they aren't the same here, I don't know, I could be being unfair, but I'm not going to use the people I care about, like you, to become my armor. If the answer is to sell them, I'll do it. Then ... everyone will be alright." Maybe not him, but that's fine, it's not like he hasn't compromised before in his life. He's all for the best case scenario.