But that wasn’t what Grace had in mind. Experimentally, she touched the tip of the pithos to her own wrist—only to see the Creation rune leap into existence there, stark and black against her skin.

“Blimey,” Christopher said. “So it can move runes from one person to another? I wonder if that’s the purpose of it, or just one of its powers?”

“You don’t seem that surprised,” Grace observed.

“On the contrary. I’ve never heard of transferring a rune between Shadowhunters—”

“No, I meant—” Grace wished she hadn’t said anything. “I only meant that you didn’t seem surprised to see me put a rune on myself.”

“Why would I be?” Christopher asked, obviously confused. “You’re a Shadowhunter. It’s what we do.”

Grace’s heart sank. Now Christopher probably thought she was completely peculiar—and for some reason, that bothered her.

But Christopher was focused on the pithos in her hands. “How might it work, I wonder?”

Grateful that the subject had been dropped, Grace handed it back to him. “All we know so far is that it can move runes from one person to another, right?”

“Indeed, but why? And just as importantly, how? Runes can’t be contained in any metal, or any substance at all, that I am aware of. So is it sending the rune to another dimension for storage, and then bringing it back? Like a miniature rune-focused Portal?”

“A… rune-storage dimension?” Grace said doubtfully. “That seems unlikely.”

Christopher gave her a sheepish grin. “I’m still in the early hypothesizing phase of my investigation.” He gestured excitedly as he talked, his hands—covered in stains and burns and scars—slicing the air. “Different substances have different properties—density, for instance, or flammability, or dozens of other things. Magical things are no exception. As an example, I have been trying to determine what adamas is made of. All things in the world are made up of elements—like iron and oxygen and chlorine and so on—and there are only a discrete number of them. Yet adamas is not one of them. Surely it has magical properties separate from its physical makeup, but—” Suddenly he stopped, looking stricken. “I’m sorry, Grace, this must be tremendously boring for you.”

Grace gathered that boredom was the reaction Christopher was accustomed to from most people. But Grace wasn’t bored, not in the least. She wished he would keep talking. But Christopher was looking at her expectantly. If there was one thing she couldn’t bear, it was other people having expectations. She would always disappoint them. “I—no, but you see, I was hoping to find some activated moth-wing powder.”

The light in Christopher’s eyes dimmed. Clearing his throat, he set the pithos on the worktable. “We only have the unactivated sort,” he said in a businesslike tone, “but we could activate it here, I suppose.”