Snape’s eyes flicked between the door and Harry, and he gave another careful nod. Keeping his wand trained on the other, Harry gave the man back his voice, but remained poised to take it away again. Snape cleared his voice and opened his mouth, "Apologies, Minerva," he called, his voice surprisingly level for someone tied to a chair, "I’ve been trying to improve the fever fighter recipe for Poppy like she asked, and I lost track of time. I’m going to be at least another hour, don’t wait for me,"