Translation: Her first impulse is to run, but feeling Caska's warmth on her back is preventing her from doing so. Caska in her current state being weak, powerless and pitiful. The trolls that watch her won't forgive her for being weak and will hunt her down even if she runs and leaves Caska to die. It's the same with animals. They respect courage and often you can get mountain dogs to back off if you don't show fear but if you do they'll come after you.