I hadn’t known I was a chimera then—she was gone by the time I’d admitted that to myself—but I’d come to trust her surprisingly swiftly, hadn’t I? She’d terrified me, and I’d trusted her anyway, because part of me knew that she was my kind. Deep down and under all the little complexities of my human mind, I’d known she was my sister. She should have been allowed to stay long enough for us to know each other.

I’d seen a lot of sleepwalkers and a surprising number of chimera since then, and I hadn’t connected to any of them as quickly as I’d connected to Anna. The only logical answer was that I wasn’t connecting to Anna at all: I was reconnecting to Tansy. Nothing else made sense.

“It’s her,” said Adam, finally abandoning his efforts to get Anna to respond to him clutching her hand. He turned to look at the rest of us, tears pouring down his cheeks. “Mom, please. You have to fix this. You have to make this better. You have to put her back where she belongs. Please.”

“I doubt Steven left Tansy’s original host intact,” said Dr. Cale. She was trying to be gentle, but there was a broken-hearted bleakness in her voice that telegraphed her distress as clearly as her tears. “Even if he did, the amount of damage he must have done digging her core out of the host’s brain… I can’t, Adam. I’m so sorry.” She looked at Anna and her breath caught, hitching her chest. She pressed a hand against her sternum, like she was trying to keep herself from losing her composure completely. Eyes on Anna now, she repeated softly, “I’m so sorry.”

“Wait—are we seriously assuming that Dr. Banks extracted Tansy’s implant from its original host and placed it in a new body?” asked Nathan. All three of us turned to look at him. Adam looked baffled, and I was willing to bet that my own expression was very similar. I spent so much time trying to think of myself as a human being that sometimes I forgot I wasn’t one. The corollary to this was that sometimes I did such a good job that I also forgot that we weren’t the same. Nathan didn’t know the things I knew. He didn’t understand the things I understood.

I could love him until the day I died, and we would never be the same species. No matter how hard I tried to pretend.

“It’s possible to remove a mature implant from its original host body and move it into a new host,” said Dr. Cale. “You know that. The implant has to be stable for the process to work, of course, but that’s not the primary issue.”

“That’s not…” Nathan’s voice tapered off, replaced by a brief, disbelieving burst of laughter. “That’s not the primary issue? You’re talking about cutting open a chimera and scooping them out of their own heads, and that’s not the primary issue? I knew it could happen, but come on, Mom! This is… I don’t even know what this is.”

“The tapeworm’s neural structures are not as advanced as a human’s,” said Dr. Cale. She sounded calm, but she was still crying. That was somehow worse. If she’d sounded angry, or even upset, her tears would have suited her better. “We discussed this when Sal was having her medical issues. The majority of her memories and thought processes are managed by the human brain she has attached herself to. It’s backup storage for what her tapeworm mind can’t manage.”

“Uh, could we not talk about me in the context of a tapeworm mind and a human mind?” I asked. “It makes me really uncomfortable when you talk about me like that.” The drums that were pounding in my ears skipped a beat before settling on a new, slightly irregular rhythm. My stomach clenched. I clung to those signs of physical distress as hard as I could, marking them as evidence that my body belonged to me, to Sal Mitchell and not to anyone else in the world. I wasn’t a human or a tapeworm. I was a chimera. A perfect marriage of the two.

“I’m sorry, dear,” said Dr. Cale. She even sounded like she meant it. Her attention remained primarily fixed on Nathan as she continued: “When a chimera has to be split, for whatever reason—when the implant is removed from the host—they lose everything that makes them the people that we know them to be. All the memories remain behind. They can’t carry them into their next incarnation.”

I stiffened, suddenly thinking of Ronnie. Tiny, violent Ronnie, who knew that he was male, even though his implant was genderless and his host was female. “What about the epigenetic data?” I asked, and was amazed by the words that were coming out of my own mouth.

Apparently, so was Dr. Cale. She twisted in her chair to shoot me a look that was midway between amazed and impressed, and said, “The sample set isn’t large enough for us to make predictive judgments about the epigenetic data. We don’t even know for sure that it’s a factor.”

“Ronnie—the chimera who let me out of Sherman’s mall—I told you about him, remember?” When the others nodded, I continued: “What I didn’t tell you was that he’s currently in a female host body, but had been in several previous hosts, all male. And he knows he’s supposed to be male. He hates his current host.”

“Maybe someone else told him about the previous hosts,” said Nathan hesitantly.

I shook my head. “No. Sherman hated that Ronnie insisted on being referred to as male, and said it would attract inappropriate levels of attention. I don’t think Ronnie would have known about those hosts if he hadn’t known something was wrong with the one he’d been put in, and gone looking for more information. Sherman and Ronnie both said Ronnie’s insistence that he was supposed to be a boy came from the epigenetic data. He didn’t have a gender identity when he was just a tapeworm. Then he inhabited a male body, acquired a male gender identity, and took it with him when he was transplanted.”