Dennis looked at my father.

After a moment’s silence, my father said, “We’re conducting some research into a class of compounds known as perfluorocarbons.”

I must have appeared puzzled. “We’re attempting to emulsify them,” he went on, “to enable them to carry oxygen.”

Normally I would have asked a hundred more questions, but this level of technical detail was beyond me. All I said was, “How nice.”

Dennis changed the subject abruptly. “Tell me, Ari. What’s that thing around your neck?”

I pulled the little flannel bag away from my neck for him to inspect. “It’s lavender. It’s meant to bring me good luck.”

My father said, without emotion, “I had no idea that you were superstitious.”

For weeks I’d been hoping that my father would resume our conversation about Poe and bereavement, but he always directed our lessons elsewhere. I’d arrive at the library armed with two or three provocative remarks guaranteed to reengage him in personal revelations. Within seconds we’d be deep in a very different conversation — about Alexis de Tocqueville or John Dalton or Charles Dickens. An hour or so after lessons ended, I’d remember my resolve and marvel at his ability to deflect it. At times I was convinced that he hypnotized me. Other times, I realized later, he distracted me by extended metaphors; he launched into them easily, spinning them as he spoke.

“In Hard Times, Louisa looks into fire and contemplates her future,” he said one afternoon. “She imagines herself spun by ‘Old Time, that greatest and longest-established Spinner of all,’ but acknowledges that ‘his factory is a secret place, his work is noiseless, and his Hands are mutes.’ But if his factory is secret, his work and hands are mute, how does she know Old Time? How indeed do any of us know time, except through our imagining it?”

He seemed to have made an extended metaphor of an extended metaphor. Was there a special name for that? I wondered. Perhaps metametaphor?

Sometimes he made my head ache.

Nonetheless I was a persistent student. Finding out something, anything, about my parents and their past seemed far more important than Dalton or Dickens. So I concocted a plan.

On a Wednesday afternoon, when Dennis was scheduled to lead me through a zoological lesson focusing on eukaryotic cells and DNA, I said that I had a related topic to discuss: hematophagy.

Dennis said, “Oh yeah?” He gave me a quizzical look. “Yeah,” I said — a word I’d never use around my father. Dennis’s teaching style was considerably more relaxed.

“I read about it at the library,” I said. “You know, animals who drink blood. Like worms and bats and leeches.”

Dennis opened his mouth to interrupt, but I pressed on. “The encyclopedia said hematophagy has two classifications: obligatory and optional. Some animals feed only on blood, while others supplement blood with additional fluids. What I need to know is —”

Here I hesitated, not sure how to proceed. I need to know what sort my father is, I thought. I need to know if hematophagy is hereditary.

Dennis put up his right hand — the gesture he’d used to signal me to stop when he taught me to ride a bicycle. “That’s a topic you’ll want to broach with your father,” he said. “He’s worked with leeches and such. In that area, he’s the expert.”

In frustration I raked my hands through my hair — and I noticed how closely Dennis watched me. He noticed me noticing him, and his face reddened.

“Ari, what have you been up to while I was away?” he said.

“I had my first kiss.” My words weren’t planned.

Dennis tried to smile. It was a little painful to watch. He clearly felt uncomfortable, but he wanted to hide his feelings.

“I know that you’re growing up, and that you have questions,” he said, sounding exactly like my father.

“Don’t talk down to me,” I said. “You’re my friend — at least I always thought so.”

He blushed again. “I’m your fine freckled friend.” But his voice sounded doubtful.

“Please,” I said. “Tell me something. Tell me something solid.”

His face resumed its normal easygoing expression. “Let me tell you about Seradrone, about our research.”

He talked about the growing need for artificial blood, as fewer people are willing to volunteer as donors. Although Seradrone had produced blood supplements, so far neither they or anyone else had been able to develop a clinically effective blood substitute.

“We thought we were onto a breakthrough,” he said. “Unfortunately, what our studies in Japan showed was the potential for retention in the reticuloendothelial system.”

I put up my hand, to stop him. “You’ve lost me.”

He apologized. It was enough for me to know that the promise of perfluorocarbons had proven rather limited, he said. “Now we’re back to looking at hemoglobin-based oxygen carriers — and so far none of them can replace whole blood, either; they merely supplement it.”

I didn’t want to ask any more questions. He’d told me more than I could understand.

Again, he was watching me closely. “Let’s schedule a checkup for you tomorrow,” he said. “You look pale.”

The next day Dennis took a blood sample from me and ran some tests on it. He later reemerged from the basement with a large brown bottle in one hand and a foil packet and a hypodermic needle in the other. He said that the test hadn’t been conclusive for lupus. But I was anemic, he said, and I should take a tablespoon of tonic twice a day.

After he handed me the bottle, I unscrewed its top and sniffed. “Yuck,” I said.

“Take it with a large glass of water,” he said. Then he opened the packet, removed a swab, cleaned my skin, and gave me an injection. I asked him what it contained, and he said it was a hormone, erythropoietin. He said it would bolster my red blood count. I did feel a surge of energy afterward.

Later I remembered what Dennis had said: the test hadn’t been conclusive for lupus. But hadn’t my father told Mrs. McG that there was no blood test for lupus?

The following morning I got into trouble at the library.

On a rare October morning without rain. I’d ridden my bike downtown to use the computer. Why should I pester my father about hematophagy? He’d only change the subject.

It took me all of a minute to find a link to “human hematophagy,” and two more to learn that many humans drink blood. African Masai, for instance, subsist largely on cow blood mixed with milk. The Moche society and the Scythians indulged in ritual-istic blood-drinking. And stories of human vampirism were abundant, although whether they were fact or fiction was a matter of fierce Internet debate.

My next link took me to a series of sites related to “Real Vampires.” These sites described some of the differences between the vampires of folklore and fiction, and those of contemporary reality. The sites disagreed about whether real vampires were dependent on drinking blood, about whether vampires could “evolve,” about whether they could bear children, and if they could, whether the children would be vampires. In short, they didn’t offer me any real answers.

One article by someone called Inanna Arthen concluded: “Furthermore, this article is not intended to mislead — real vampires, even evolved ones, do sometimes drink blood in order to obtain their energy. Those who understand the many ways that life ‘gives way’ to nurture more life will see this as no more unnatural than eating live vegetables or animals for food.”

I was musing about this when the librarian put her hand on my shoulder. “Why aren’t you in school?” she asked. She was an older woman with wrinkled skin. I wondered how long she’d been standing there.

“I’m home-schooled,” I said.

She didn’t seem convinced. “Do your parents know that you’re here?”

I thought of telling her the truth: my mornings were my time in which to study as I pleased, before I met with my father after lunch. For some reason, I didn’t think she’d believe me. So I said, “Of course.”

“What’s your home telephone number?” she asked. And like a fool, I told her.

Next thing she was talking to my father. While we waited for him to arrive, she had me sit on a chair before her desk. “I’ve seen you in here many times,” she said. “Are you always Googling vampires?”

Like a complete idiot, I smiled. “I find them interesting,” I said brightly.

I must confess that when my father finally swept into the library, his long black coat buttoned to the chin and black hat pulled almost to his eyes, the librarian’s reaction was something to see. Her mouth dropped open, and she let us leave without saying another word.

But on the drive home, my father said plenty, ending with: “— and so you have managed to disrupt an important experiment, whose results may now be compromised, and for what? To annoy a librarian with questions about vampires?” But his voice held no emotion; only his choice of words, and the slightly lower tone of vampires, let me know that he was angry.

“I never asked her questions,” I said. “I was trying to do some research on the computer.”

He didn’t say more until we were back home, and he’d put the car away. Then he came into the front hallway and began to unwind the scarf from his neck. “I suppose it’s time we talked” — he paused to remove his coat — “about giving you your own computer.”

By the time Kathleen called a few nights later, I was the proud owner of a sleek white laptop with a wireless Internet connection. I told her the story of its acquisition; it was rare that I had anything interesting to talk about lately, and perhaps that’s why her calls had grown infrequent.

Kathleen responded to the tale of the evil librarian with appropriate “You did not!”s and “Really?”s. “You should have lied,” she said when I’d finished. “You could have given her the wrong phone number. You could have given her our number, since nobody’s at home during the days.”

I admitted that I hadn’t been clever with the librarian.

“But it all worked out,” Kathleen said. “Your dad’s not mad — he bought you your own computer. You’re so lucky.”

I didn’t think luck was a factor, but I kept quiet. The computer, it occurred to me, was a convenient means for my father to avoid answering my questions. He seemed to want me to find the answers on my own.

It was around this time that I attended my first dance.

Michael telephoned (for the first time ever) to invite me, and he sounded nervous. “It’s just a dance,” he said, sounding needlessly argumentative. “It’s the stupid school Halloween dance.”

Halloween was not celebrated at our house. Every October 31, Root pulled all the window shades and locked the door. No one responded to the occasional pounding of the door knocker. Instead, my father and I sat in the living room playing cards or board games. (When I was younger, we’d also played with a Meccano set, which we used to build a machine that moved pencils from one end of the dining room table to the other.)

We were particularly fond of Clue, which we played in rapid games never lasting more than three turns each; at the McGarritts, I learned that others took much longer to solve the crimes.

I told Michael I’d have to ask my father’s permission. When I did, my father surprised me. “It’s your decision,” he said. “It’s your life.” Then he turned back to his reading, as if I weren’t there.