Well, there's a reason for that, isn't there? The fire is there, he knows it is, simmering low and waiting for a reason to be unleashed.

Just to demonstrate he turns his head away from her, lest he risk catching her by mistake, and giving a short, purposeful burst of flame. It swells and billows upwards in the air before vanishing, and that heat? Seems to rise under his scales as he does so, before slowly simmering down once again.

At her request, he gives her a slightly doubtful look before sinking down as low to the ground as he can manage.