"Ummm...," Rodolphus chews his lower lip. "You know subtlety isn't my strong suit Severus. I'm apt to hex first and ask questions later." He raises an eyebrow. "If they're capable of answering that is," he adds. But," he goes on before Severus can say anything, "I did say I wouldn't do that." He drums his fingers on the arm of the chair. "How long have you been here Severus? And you never did say what a miasma-filter is."