"Aren't working," Sirius replies, that worry that had flickered earlier suddenly flaring bright all over again. "Is this something that's happened before?"

Except, of course he knows the answer to that. There'd clearly been something wrong to cause Kieren's last rabid spell, a case of his drugs not working or something otherwise going awry. Kieren hastily brings the rag to his face again and Sirius feels another spike of panic. "Should I get Newt?"