My fingers itched, and the only cure, I knew, would be grabbing hold of her and never letting go. I rubbed them together, trying to make the feeling stop. “I’m going to go find Adam,” I said. “He needs to know that this is happening, and that there’s another chimera in the building.”

“All right,” said Nathan. He bent to kiss the top of my head. I hugged him quickly, taking what pleasure I could from the contact. “We’ll be here.”

“I know,” I said, and turned to run deeper into the lab.

Adam and I were the yin and yang of Dr. Cale’s chimera research project, in more ways than one. He was created in the “traditional” way, when she introduced an immature D. symbogenesis directly into the brain of a subject in a persistent vegetative coma. The body’s original owner was already long gone, leaving an otherwise healthy habitat for the new tapeworm intelligence that would inhabit it. I was an accident, born of trauma, stress, and lucky chance. My memories began at the moment I fully integrated with Sally Mitchell’s brain, but according to Dr. Cale, the last act of my old life had been a panicked flight through her body, culminating with my burrowing into her skull and beginning the integration process. He was induced, I was natural; he was nurtured as a chimera, I “grew up” believing myself to be a human being. I had spent the last few months stumbling from one dangerous situation to another, while Dr. Cale kept Adam in the lab, as confined and protected as possible. She said that she hadn’t allowed me to spend so long outside of her care after my accident just so she could monitor our development under different types of clinical pressure, and I actually believed that she believed that.

At the end of the day, Dr. Cale loved Adam very much, and wanted him to be safe. I couldn’t blame her for that. She’d been his mother for the entirety of his life, while I was more like the child she’d helped someone else bear through egg donation: genetically connected, socially and emotionally very, very distant.

“Adam?” I slowed as I reached the edge of the lab hydroponics section, which was used mostly to grow herbs and local mushrooms. There was a large artificial bog filled with sundews, which I appreciated—Nathan and I had our collection, but he had “liberated” several more from florists and taxidermy shops when he was helping to collect hydroponic and preservation supplies. Sundews were bog plants, which made our old friend Marya’s admonition not to overwater them even funnier. She’d been trying to keep us from killing them with chlorine, of course, and the language barrier had simply been complicating her instructions.

Marya was probably dead now. She’d owned and operated a flower shop within the general footprint of San Francisco City Hospital. Even if she hadn’t had an implant of her own—and I didn’t know whether she did or not; I had never asked her, and it was too late now—there had been mobs of sleepwalkers in that area during the collapse. There was very little chance that she had survived.

I sometimes wondered how the rest of the people on Dr. Cale’s team could stand it. I had only had a few years to form connections with other people, and I could still be blindsided by the strength of how much I missed them.

But this wasn’t the time to dwell on what we’d lost. “Adam,” I called again. “It’s Sal. The duty roster says you’re supposed to be here, so where are you? Come on, Adam. I know you’re there.”

“How do you know?” asked a voice from behind me. I turned, but I didn’t see Adam, just the shapes of three large potted avocado trees. “Maybe I’m somewhere else. Maybe I’m nowhere near here at all.”

“Well, since we don’t have intercoms this good, and the cell system went down weeks ago, the part where you’re talking to me means that you’re here,” I said. “Apart from that, I know you’re there because I know you’re there.”

The leaves on the avocado trees rustled and Adam’s face appeared, pale through the gloom. I was paying attention now, brought to high alert by Anna’s presence: I didn’t feel the same drive to protect that I felt for her, but he wasn’t in danger, was he? I already knew that Adam was safe and well, and on the few occasions when I had been afraid he would be hurt, I’d had the same response to him that I had to her. Chimera, standing together. So no, I didn’t need to protect him… but I was aware of him. I always had been. I just hadn’t been able to consciously name that feeling before I had someone else to check it against.

“The scientific method works,” I murmured.

Adam blinked but didn’t ask me what I meant. He was always good at ignoring things that didn’t make any sense. “I felt them bring her into the building,” he said. “It was like as soon as she was here, everything was whole again, instead of being broken the way that it has been for days and days. Do you think she took Tansy’s place?”

“What? No.” That answered the question of whether or not he knew about our visitor. But he knew Anna was a “she,” and tapeworms are hermaphrodites: he was a boy and I was a girl because of the human bodies we’d grown to inhabit, and not because we were innately gendered creatures. “No, Adam. Tansy is… Tansy is our sister. I don’t know where she is, or whether she’s okay, but I do know that no one is ever going to take her place in our lives. We’re going to find her. We’re going to bring her home. I know it.” There was something wrong with that answer, something that gnawed at the back of my mind with sharp, unforgiving little teeth. Anna held the key to finding Tansy. I knew she did. I just didn’t know how I knew, or what that knowledge was going to mean.