(Start here.) (Or just go backwards.)

We followed him through the tunnels, and Emily tried to talk to him. “Ernesto, what are you talking about? Is this just some stupid thing you and your jerks are doing?”

“I am no longer Ernesto,” Ernesto said, his voice cool and flat and somehow off. It scared me, but Emily just kept talking.

“Nice try, but you are Ernesto, because duh, I know you from school. You’re the jerk who throws spitballs at Ms. Martinson, and is friends with Joey, and Abdul, and Garret, and you’re in my Spanish class.” She paused, and we just walked along with him through the tunnels, and he didn’t say anything, and the longer he didn’t say anything the weirder it felt. “You came to our school in fourth grade!” Emily insisted. “You were adopted from Darfur, and so I was going to be really nice to you but then you ended up being a jerk.” Her voice got less convinced with each word, and finally she just stopped talking. And then we turned a dark corner and stopped.

It was a room off the hall, and it was filled with people—dozens of them. The red-haired lady was there, and she had that same expression, that about-to-scream scowl. But there were other people too, and they were milling around and not talk to each other at all. They were quiet, and walking slowly. Emily reached over and took my hand, and I let her. I tried to say something, but my mouth was too dry.

They moved stiffly, like puppets someone hadn’t fully learned to operate yet. Ernesto walked in with them, and they turned to face us, all stiff and strange. The lady with the red hair spoke first. “We are the shadows.”

I tried to say something back—I was all ready to, but somehow I couldn’t. My voice dried up in my throat.

“Yeah, except he’s not a shadow,” Emily looked at Ernesto, her voice trembling. “I know him from school, and he’s a regular person not the expression of a bad connection or whatever you—.”

“I am not Ernesto,” Ernesto said, and Emily stopped, her face pale. He turned to me and so did the rest of them. “I am using Ernesto’s body. I am a shadow, and you, and we, both need something: your mother’s work.” He took out a piece of paper and my heart went sharp: I recognized my mother’s handwriting, her equations scribbled across the center.

“That’s my letter!” I said. “That’s the one you stole! Phoebe sent it and it’s mine,” I said to the red-haired lady.

“Wait,” Emily said, ignoring me. “What do you mean you’re using Ernesto’s body?”

“Should you be the only ones to be embodied?” he said. “Should you be the only ones to experience the physical world?”

Emily looked sort of shrugged. “Well, yeah, if it’s our body. What are you—demons who possess people or something?”

“Demons?” Ernesto shook his head slowly. “We are part of you—connections, that’s all. We come from you.”

“But—,” Emily said.

“Give me my letter,” I said. “It’s mine.”

“Only if you give us something in return,” Ernesto said, and he smiled, except it didn’t look like a smile.

“What do you mean?” I said.

Emily was shaking her head. “Don’t,” she said under her breath. “Whatever they want, don’t give it to them.”

But I shook her off. “What do you want?”

He held up the letter, letting it dangle from his hand. My mother’s handwriting hung there. The shadows murmured among themselves, and it felt like the temperature changed—a buzzing rose up in them. And then Ernesto—or the shadow using Ernesto’s body—said, “What is it that you want?”

I took a deep breath, and tried not to notice that Emily and Adam were both shaking their heads at me. Because they didn’t understand: I’d messed everything up, and now was my chance to fix it. “OK. Here’s what I want. I want my mom back. And I want this whole thing, with us disappearing—I want it to stop.” I thought that was pretty good, for a start.

“You know, we know it’s genocide,” Emily said. “Alyssa killed all the lizards, and now you’re killing all the humans. And that’s just wrong!”

The shadows looked at one another and they started to make this horrible dry creaking sound, like crunching bones. It took me a moment to realize they were laughing.

“What?” I said. “What!”

“We?” Ernesto said when he could catch his breath. “Of course! Of course you would think that, it is so human. It is not we who are responsible for genocide.”

“What are you talking about?” I asked.

“We do not perpetrate genocide,” the old lady said. “You do! We cannot even control these bodies to do the slightest physical violence yet. But you! You’ve been doing violence for years!”

“What?” Emily said.

“Wait, no, that doesn’t make any sense,” I said. “Why would we do genocide to ourselves? That’s the stupidest thing I ever heard.”

“To yourself? Who else would you do it to but other humans?” she said. “You are humans, are you not? You’re the only ones that do it to your own species. Where do you even think we came from, after all? We’re intentions—your intentions.”

I hesitated. “Well, yeah, but I mean, genocide isn’t anything we did. It’s more like we were victims of that.”

“All of us,” Emily said, and we looked at each other fast. “That’s why we’re disappearing.”

“Yeah,” I said. “It’s not like all humans are in favor of genocide or something. My grandmother was almost the victim of genocide.” They were looking at me closely, and I got encouraged. “It targeted her, you see? It was against a specific group of people.” The old lady just shook, and watched me. “So it’s you guys doing it, is what I mean,” I finished lamely.

“I think maybe you have the wrong people, you know?” Emily said.

Ernesto shook his head.

“But come on!” Emily cried. “I mean, Ernesto, you got adopted from Darfur. You’re a victim of genocide—I mean, you’re a person who escaped it, that’s what I mean. That’s—oh.” She went pale.

“Yes,” Ernesto said. “This is how we were able to take advantage of this particular body so speedily.”

Adam spoke then, his voice almost soft. “How are you doing it?”

Ernesto nodded. “Consider: you do this to one another all the time. One group of humans tries to destroy another group of humans—over and over. And each time a few lucky ones slip through the nets. Like your grandfather’s grandfather’s grandfather. Or your great-aunt. Or your grandmother.” He nodded at us. “Or this Ernesto,” and he gestured down at himself, like his body was a suit of clothes he was trying on. “But what if they didn’t slip through? What if humans actually accomplished what you set out to do? All we must do is stand by and reap the benefits.”

“We’re not trying do accomplish this,” I said. “It’s only monsters who do genocide, OK? Like Nazis or something. Not regular humans.”

“Really?” the old lady said. She’d stopped shaking, but she still moved a little stiffly. “What are they if they’re not human?”

My throat got tight and my armpits prickled, like I was getting a math problem wrong in front of the whole class. “Well, I mean the ones who planned it were monsters, sort of like human monsters, and then other people got confused,” I said, trying to remember why she was wrong, because I was sure she was wrong. And then I thought of something. “Besides, what about all the people who saved people, huh? There were a whole lot of people who helped other people escape. Someone helped my grandmother.”

“Exactly so, the loopholes,” the shadow Ernesto said. “Except, it turns out that there are actually very, very few people who do that, did you know? I mean, honestly, do you think you would do so? Are you so very good and brave?”

“Some people are,” Adam said. “Some people must be.”

But the shadow looked at me through Ernesto’s eyes. I tried to remember if I gave any money to annoying Sally Fanshaw at my old school, who was always collecting money to save people in Darfur. I felt a little sick. Ernesto nodded and said, “So you see, if somehow those few loopholes were closed off….”

“Then the person the loophole saved wouldn’t have survived,” the old lady said. “And if you’re clever enough to manage time neatly, you can take advantage of the body, which is now available.”

“But they did exist,” I said.

“But what if they didn’t?” Ernesto said. “What if people had a few more bad connections? Don’t you think that would make a rather large difference?”

“Yes,” I whispered. “It would.”

“So you may think you are not like the monsters,” the lady said, and she laughed that creaky broken laugh, “but it’s not only useful to us that there are these humans—oh, excuse me, monsters—but also that there are so few willing to challenge them.”

“But there were some,” I said.

“We really don’t have time for this,” Ernesto said, waving my objections away. “You are humans, like other humans. And so you must live with what that means. But,” he turned to me, “you can help us, which makes you different. We would like to see what your mother has for you. If you bring us the package, we will simply exempt—your grandmother’s loophole, was it?”

“Yes,” I said numbly. “My grandmother.”

“It shouldn’t be too difficult. We are rather more adept with time and change, particularly those of us who have not yet taken on these bodies, which really slow you down. At any rate, it’s simple: you get us what we need, we leave your grandmother’s meager loophole open. And you can see your mother.”

“My mother? You have my mother?”

“Can you get what we need?” he said back, without answering me.

“Why can’t you ask her?” Emily said, and my skin felt hot and cold at once. Because it seemed like there was only one way to explain why they couldn’t get it from her, and that was that she was dead.

“Is she alive?” I asked, my voice thin.

There was an almost imperceptible pause, and then Ernesto said, “Yes. But you must give us what we need. Whatever goes with this letter, whatever she sent you. That’s the exchange.”

“For real?” I said. I heard Emily take in a sharp breath next to me, but I couldn’t stand to look over at her. “Can you really do that?”

The thing that used to be Ernesto almost smiled. “With your grandmother’s loophole? Of course. It’s bodies that are more recent that are going first—those from Darfur, Rwanda,” he said, gesturing down at himself. “Hers is from longer ago, yes?”

“Yes.” I thought about how my grandmother got out, the person who worked in the kitchen who took her home and let her stay with her dog. “It’s 60 years or something.”

“Alyssa,” Emily whispered, her voice thin and tight.

But I ignored her. “Yeah, I want you to do that, I want you to exempt my grandmother. I want to see my mother.”

“In exchange for decoding this information from your mother.” He held up the letter.

“Yes,” I said, though I felt Adam and Emily stiffen behind me. But they were going to find out what sort of person I was sooner or later.

And then Ernesto, or what Ernesto was now, almost smiled. “Then do so in one hour. Any later and it will no longer matter.”