"You're assuming she wouldn't leave too. What if everyone in Thorne could leave if they wanted to? It happened before." Jesper isn't saying he has the answer for this but he also isn't against coming up with an idea if things start to look dire there. He's worried. It doesn't show really, outside of people who know him, and Mat's starting to become one of those people. It's in the lack of his usual humor, mostly. Jesper isn't always making jokes, but he usually is very light.

"Don't be so down on yourself, love. You're much more than you think you are, and anyone with a few braincells can see that." Including the people he probably doesn't want to know. Jesper isn't that concerned about Thorne trying to force them into it, but he is moderately concerned about them being used as hostages. It would work.