She propped her hand on his head, rewarding him for his obedience. Holding something like that over his head was perhaps cruel, however, it was better than the alternative, risking him more physical strain.

Astrid sighs sympathetically, thinning her eyes on Zuko a moment. "Hey. You're condoning this? I understand you have an obligation to help him, but he won't be any use to you dead."

Now back to the boy. Her eyes bore into him harshly. "What are you thinking! Really. How do you expect to get better like this? Keep pushing yourself to your limit and you'll really die!"