In his anger, in his desire to lash out and break that rock-solid facade, Hephaestus had forgotten why he had even come. He felt his immortal frame panic at her words. This mountain, this ground, this palace--it was all too easy to imagine pain here, betrayal. The place stank of it to Hephaestus.
Eventually though he realized what she had done. Twirled him around like the slow fool he was. He had no reason to panic. He had not come here to wage war, or to die. He had come for his prize. A moment earlier he had been ready to throw it away for a chance to spit in Hera's face. He could see though that he'd never succeed that way. But he could take his own measure of triumph.
His panic receding as he gripped tightly to the idea of his triumph, his prize, his place on the mountain, Hephaestus raised his eyes to Hera once more. "Go ahead. I can trap you but I can't stop you from speaking, gods know." He crossed his arms. Let her rattle her mouth and then he would tell her why he had truly come, and with what glory her son would be ending this day.