"No, the muggles. Petroleum is the remains of ancient dead things." Severus nods approvingly. "Only thing he could do," he affirms, "really. How did she take it?"
"Again, not random. One does like to be able to pinpoint the cause of a sudden period of unconsciousness, don't you know."
"Well, of course we can," he says judiciously. "But if we did, they'd understand it, you see. They would think that revisiting us with greater force later, with or without them being present in battered person, would have an effect. They would take it as business and learn nothing except that we are not so weak as to be diddled with the insignificant force they'll be currently planning, and to a bully who's had his pride hurt, that's no lesson at all."