“It can’t hurt.”

I walked to Barabas’s house. Here’s hoping Christopher was lucid.

Barabas let me in and went back to the Guild Manual. I found Christopher on the floor of the downstairs living room, sitting on a rug, surrounded by open books. His face lit up when he saw me, his eyes clear.

“Mistress.”

“Hi, Christopher.” I sat on the carpet outside his book fort.

“I’m glad you didn’t die.” He smiled.

“I’m glad I didn’t, too. I’ve come for advice.”

“My mind is shattered,” he said. “But I will try.”

“What do you know about ghouls?”

“Ghouls are the fallen djinn,” he said.

“Fallen like demons are the fallen angels?”

He leaned back, shifting his weight. “The djinn are creatures of magic. They require it to survive. The more magic, the more . . .” He struggled for a word.

“Powerful? Larger?”

“Evolved. When they lose their magic, they become ghouls. They are fallen.”

Christopher held his hand out, parallel to the floor. “Ghoul.” He raised his hand up as far as he could. “Marid.”

I nodded. A marid would have much more magic than a ghoul.

Christopher struggled with it for a few seconds and brought his hands together into a ball. “One S. Two S. Two P. Three S.”

And I lost him. “I don’t follow.”

Christopher frowned. “One S.” His hands moved wider. “Two S. Two P.”

“He is talking about the electron configuration of an atom.” Barabas came over with a piece of paper and a pen, sat next to me, and drew a circle on the paper. “This is the nucleus of an atom, protons and neutrons bunched together into a mass. It has a positive charge.”

He drew a circle around it and put a dot on it like a planet around a star. “The electrons have a negative charge. They have set orbitals.” He drew another circle, wider, and then another. “These orbitals are identified by scientific notations. This lowest one is 1s. This one is 2s. This bigger one is 2p. The farther away the orbital, the more electrons it can fit. The first can fit two, the second can fit eight, and so on.”

“Okay.” This was way above my pay grade, but if I could learn cuneiform, I could learn about electron orbits. “What does it have to do with djinn?”

“I’m not sure.” Barabas looked at Christopher.

“The electron jumps.” Christopher said. “It’s excited.”

“Ah. The electron can exist in two states: the ground, or lowest energy state, and the excited state. To make it really simple, the electron naturally wants to stay at the lowest orbit. However, if the electron absorbs some energy, it might ‘jump’ to the next orbit. I’m bungling this badly, but it’s been a long time since college chemistry. For example, if you have a neon atom, it has a configuration of 1s2 2s2 2p6, if I remember correctly. If we give it some energy, by shining a light on it for example, one of these electrons might ‘jump’ to a higher orbit such as 3s or 3p or sometimes even 5s. Then the electron emits the energy in a form of light and ‘falls’ back to the ground state.”

“Djinn,” Christopher said helpfully.

“So let me get this straight. A ghoul is the ground state of the djinn. The lowest magical form. Then, if the ghoul somehow gets some magical energy, it will evolve to a higher-order djinn, just like an excited electron jumping to the farther orbit?”

“Yes.” Christopher smiled. “It will be what its true nature meant it to be.”

“But then it will revert back into a ghoul when the magic runs out?” I asked. “It will fall again?”

“No.” Christopher shook his head. “Higher-orbit djinn make more magic.”

“Does this make sense to you?” Barabas asked.

“Sort of. We don’t really know why ghouls are ghouls. But we do know from folklore that they were relatively rare in ancient times, when magic was strong. The other types of djinn were mentioned more frequently. Yet now we have an abundance of ghouls but no djinn. We also know that some djinn tended to interbreed with humans. If we suppose that a very small percentage of the human population carries the djinn genes somewhere deep inside. They have the djinn blood but very little magic. It follows that with the influx of a magic wave, they would transform into ghouls. Their magic is too weak for them to be anything else. That’s probably why we haven’t figured out what causes ghoulism. There is probably some sort of catalyst that initiates the change, but it’s not a disease. It’s a genetic predisposition.”

Christopher smiled at me.

“It would explain why they devour corpses,” Barabas said. “Human remains, especially after a supernatural event, have a lot of residual magic.”

“They’re probably instinctively driven to it to try to get enough magic to transform.”

Barabas nodded. “But, if I understand correctly, if a ghoul somehow got enough magic to evolve into its true form, he wouldn’t ‘fall back’ the way an electron does?”

“No, because once it’s transformed, it will gain the ability to absorb more magic from its environment and will be able to survive. It’s getting them past that threshold that is the problem.” So far this was lining up with everything my father had told me about djinn. “Christopher, could my blood give a ghoul enough energy to evolve?”

Christopher pondered it, got up, and began looking through the boxes. A minute crawled by, then another. He pulled an old book out, flipped through it, and placed it in front of me. Hmm. Alchemical symbols. Looked like standard Renaissance nonsense . . . I flipped the page. A circle, within the circle the symbol for ether, a triangle pointing down imposed on the triangle pointing up. A creature writhed in the center, caught in flames. Above it blood poured from a cup held by a disembodied hand. Let’s see, viridis flammae, green flames. Blah-blah-blah . . . Spirit of box, salt of vitriol . . .

Barabas was looking over my shoulder. “Can you understand any of this?”

“Yes, it’s basic alchemy. They used methanol and boric acid to make trimethyl borate and set it on fire. It burns bright green.” A plan tried to cobble itself together in my head. I could actually do this if all else failed.

“So you don’t know about electrons but you understand medieval chemistry?”

“Electrons don’t help me survive.” I smiled at Christopher. “Thank you, Christopher. You were great.”

He hugged me. It was such a simple wordless gesture and so not like him. Christopher didn’t like to be touched. He’d spent too much time in Hugh’s cage starving slowly in his own filth. Any physical contact had to be initiated very carefully, but here he was hugging me, so I held still and smiled at him. For a few moments we sat on the floor next to each other with Christopher gently hugging my shoulders.

Someone knocked on the door. Barabas opened it. Julie stood in the doorway. Her face said she was clearly put upon and no adult could ever understand the full extent of her suffering.

“Mahon came to talk to George, but she won’t let him in her bedroom, so they are talking through the door,” she recited in a monotone voice. “Could you please come home because Luther and some knight of the Order are here to see you and Curran can’t talk to them because he has to stand in the hallway and make sure Mahon and George don’t break the door down and kill each other.”