The woman's answer actually made him chuckle; you had to appreciate wit under pressure. S.H.I.E.L.D. agents always seemed to have a certain knack for that- the deadpan one liner just before a tragic death. It was this woman's lucky day, however, because if she behaved herself (he felt the brass like any other metal and though he couldn't manipulate it he knew well enough to strengthen his electro magnetic barrier), she might live to crack another joke. He paused several feet from them with an exaggerated thoughtful expression before he spoke again. "Oh, no, I'm quite sure you'll be interested in this. Especially when my terms are so good. Your cooperation-" his gesture included both the woman and Hammer, "In return for your life-" This was a finger extended towards the agent, which he then swiveled to point at Hammer's daughter. "And hers."
He studied the little girl for a moment before he twisted his outstretched finger, exerting pressure on the metal he could feel in several of the child's teeth. "Perhaps you shouldn't feed her so many sweets," Magneto suggested, all magnanimous fatherly advice. He tsked and shook his head as the little girl dropped the sucker in her hand and let out a squeal in pain and surprise. Magneto eased off the force he was putting on the fillings, but he was sure it had been enough to get things rolling, to put a little fear into her father. A man like Justin Hammer could do with some real loss, it was a nice character builder.