But one of the others—a sturdy girl with glasses, Walden hadn’t caught her name—said, “No?” When Walden nodded at her to go on, she said, “Well … MRS GREN, right? Movement, respiration, sensitivity, growth, reproduction, excretion, nutrition—” GCSE Biology in action; some of the others were nodding thoughtfully. “Demons do some of those, sometimes,” said the girl, “but they don’t do all of them—do they? Do demons respire? Do they breathe?”

“Only when possessing something that breathes,” Walden said. “And they don’t reproduce—at all, as far as anyone can tell. Rather, they seem to spontaneously generate in areas of high magical activity. So our answer is in fact both yes and no: demons are and are not alive, because they are life forms—we are fairly sure of that—but they are not biological life forms. In the demonic plane they generally lack physical substance altogether. Demons are magical life forms. They come from magic, and they are made from magic, and they eat magic.”

“Nutrition,” someone said.