Jesper always knew that the hatred Kaz had for Pekka was very, very deep. He wanted to ruin the man's entire life in a very personal way, and Jesper never questioned why, mostly because he doesn't question Kaz. And he assumed the man deserved it. But he can see it all now. Kaz was a pigeon once, with his brother, and Pekka ran a game on them. Damn.

Jesper reaches out as Kaz talks to put a hand on his shoulder. With Inej touching his knee, they're both trying to show comfort where they can, and not touching skin in the process. This is a horrible story and honestly disgusting, Jesper has a good imagination so he could imagine how awful this was if he wanted to, and he really doesn't want to. To experience that as a child is so fucked up.

"He was your brother. He would've wanted you to survive, whatever it took." Meaning having to use his body was legitimately horrifying, but surely his brother would have wanted that, given the chance. To keep Kaz alive. Survivor's guilt is one hell of a thing, he knows that.