“Meaning what, Mother?” asked Nathan.

“Meaning he continued the work after I left; he continued altering the genetics of the different strains and families of implant, looking for that perfect mixture of form and functionality. He didn’t toss up his hands and say, ‘Well, Shanti’s gone, better throw in the towel and stick with what we have.’ He innovated. He improved. And what we have here, on this little piece of hardware, is a collection of those innovations.” Dr. Cale raised her head, and I almost recoiled. I wasn’t human, but neither was the light burning in her eyes: bright and cold and unforgiving. “Now that we know what he’s done, we’ll know how to undo it. So thank you, Sal. Thank you both. You’re welcome to stay here for as long as you like. I recommend you consider making your residency permanent.” On this grim note, she placed the thumb drive carefully in her lap, turned herself around, and rolled out of the room. She didn’t look back once.

Nathan put his hand on my shoulder, stepping up beside me. The warmth of his body was reassuring. “Are you all right?” he asked.

I tried to answer him—I honestly did—but all that came out was a high, anxious squeal of laughter, like the sort of sound a rat might make if it was caught in a trap. Something wet was on my face. I raised my hand to touch my cheek, and found tears there, flowing freely from both eyes. My narrow window of calm had apparently passed.

I tried again to answer him, and this time there was no sound at all. The drums were back in my ears, and they grew louder as, with a great rushing roar like water pouring over a cliff, the dark crashed down and took me away.

One advantage to passing out repeatedly in the same place: you’re more likely to wake up somewhere familiar. I opened my eyes and found myself looking at the ceiling of Dr. Cale’s lab, lying on the same narrow cot that had served as my bed the last time I had fainted. Only one light was on, and it was behind me, casting the room into the sort of deep shadow that never happens naturally. I sat up, dimly aware that I wasn’t alone.

“Hello? Who’s there?” I frowned into the darkness in front of me. “So you know, I’m having a really bad day, so I’d appreciate it if you could move straight to threatening me, or making weird noises, or turning out to be on the other side of some massive ideological divide that’s going to shape the future of the human race.”

“I don’t think we have any massive ideological divides,” said Adam. He slipped out of the shadows to my left, frowning bemusedly. “Are we supposed to?”

“Oh,” I said. “Hi, Adam.” The drums started up in my ears again as my heart began to hammer. Adam was one of Dr. Cale’s human-tapeworm hybrids; the first, to hear her explain the situation. He was the oldest of us in the world. Everything I was experiencing was something he had experienced before me… and also not, because he had never spent a moment thinking he was anything but what he was. When he’d opened his eyes for the first time, it had been onto a world filled with people who knew his origins, accepted them, and didn’t try to make him into something else.

That must have been nice. I couldn’t even imagine how nice it must have been. Dr. Cale had created him intentionally, combining samples of her first-generation D. symbogenesis worm with a brain-dead boy whose parents had basically sold him to her in exchange for escaping his mounting medical bills. I didn’t know what his body’s name had been before Adam took possession. So far as I was aware, he didn’t know either. It had never really mattered. That boy was gone, and Dr. Cale had never known him. She’d raised Adam without any shadows that wore his face to follow him around and make him feel bad for existing.

“Where’s Tansy?” He took another step toward me, the light revealing more of his features. He was skinny and pale, with the sort of face that was practically designed to blend into crowds, just conventionally attractive enough not to stand out, too essentially plain to snag in the memory. He had blue eyes and sandy brown hair, and even though we didn’t look a thing alike, something deep in my core was telling me that he was my brother: more my brother than Joyce had ever been my sister. Adam was family. And family had to stick together.

That feeling had always been there, I realized, but it was getting stronger from the combination of proximity and understanding. I wasn’t in denial anymore. I could accept all the parts of what I was—and that included my brother.

Adam was also frowning, confusion and dismay becoming more pronounced with every second that passed without my giving him an answer.

“She went with you,” he said, his tone implying that I might have forgotten—like I might have been distracted, or hit my head when I fell down and hit the floor. “That’s what Mom said. She said that Tansy was going to get you out of SymboGen so that you and Nathan could both come home, and we could finally be a family the way that we were supposed to.”

The pounding of the drums didn’t lessen, but it was joined by another, less pleasant sensation: my stomach, slowly converting itself into solid ice. If Adam was my brother, Tansy was my sister. Oh, God. Did my sister die to save me?

No. Not possible. Tansy was too mean to die that way. “Tansy was… she was there, yes. She’s the reason I got out of SymboGen. I don’t think I could have escaped without her.” That wasn’t quite true. I knew that I wouldn’t have escaped without her. Tansy had been the motive force driving my escape from the building, and it was only her willingness to stay behind that had bought the time Nathan and I needed to get to the car. Without Tansy, I would have been a prisoner, or worse.