Teresa finds the first site right after she gets back from maternity leave, Daniel snug in a baby sling at her chest. He’s quiet as far as babies go, sleeping through the night already, and she’s grateful: she can’t have him interrupting her career more than he already has. She swore to herself she wouldn’t compromise on motherhood or archaeology, and so far, she thinks she’s managed to keep the promise.

She’s in northern Brazil, deep in Monte Alegre State Park. The most heavily researched archaeological sites in the country are coastal, but Teresa and her collaborators work in the interior. They got a tip-off about this cave system from a local tour guide who’d stumbled across it during a hike. It’s a hot day, easily forty degrees Celsius, and Teresa would be sweating even without Daniel’s extra weight.

“Teresa,” calls one of her Brazilian colleagues. “Vem ver isso aqui!”

She picks her way across the ground, forcing herself not to hurry. She shouldn’t have brought Daniel, she thinks absently, and then she’s staring at where her colleague is pointing and not thinking about Daniel at all.

This cave, by their estimates, hasn’t been inhabited by humans in centuries. Yet there it is, plain as day, scribbled in what looks like permanent marker on the wall.

You were right, it says, in English. I miss you.

---

In 1973, elsewhere in Brazil, archaeologists discovered cave paintings in rock shelters at a site called Pedra Furada. Nearby charcoal remains were carbon-dated to thirty-five thousand years ago, roughly twenty thousand years before other evidence of human presence in the Americas. A momentous discovery, to some. To others, easily explained away by confounding factors: the charcoal could’ve been unlinked to the cave paintings; it could’ve been produced by forest fires; it could’ve been newer remains mixed with older traces.

So. Just like Pedra Furada, there are a thousand other explanations for Teresa’s first find. The graffiti only means their site is compromised in some way. Nobody looks at six little English words and says, Yes, those are the same age as the rest of our site. Certainly not Teresa.

At least, not until she radiocarbon dates the pigments in the message. Then she stares at the output blankly, grip tightening against the edge of her desk. Then she thinks, fleetingly, of Iara.

---

The current biggest advocate for time travel technology is a Brazilian scientist named Iara Cambaúva. She is famous. She is brilliant. She is Teresa’s ex-wife.

---

Teresa buries her anomalous discovery in a footnote to a scientific paper, acknowledging with as much academic honesty as she can manage the “possible issues with our radiocarbon dating techniques.”

Possible issues, despite the fact that she calibrated the spectrometer a dozen times after she pinned down the age of those words. She’d done it in a fevered rush to confirm what she already suspected. She hoped it was something wrong with her science; something wrong with her tools. Afterward, she sequestered herself in a locked supply closet to pump for Daniel, mind and body both aching.

She doesn’t believe what the data says. Truly, she doesn’t, and she keeps on not believing it until she finds the second message seven years later.

---

In the interim, she survives Daniel’s childhood.

That’s being overdramatic, probably. There was discounted staff daycare at her home university in Canada. She brought him to her office sometimes, settling him on a playmat with sets of colored blocks while she reviewed journal articles. When she was in Brazil and couldn’t take him with her to sites, she paid babás recommended by her local colleagues to look after him. And on a few occasions, with intensive conference or fieldwork schedules, she left him with her parents in Canada while she was working.

Still, it wasn’t easy. Her sleep schedule tanked, her sick days evaporated, and she discovered the uniquely difficult delights of an intelligent child. When Daniel got diagnosed with strabismus at age seven, he brought his emerging powers of persuasion to bear in an all-out war against the patch he was supposed to wear on his dominant eye. He was constantly plotting ways to get her to take it off.

He tried an ambush maneuver after he faceplanted off the monkey bars and sheared off half his front teeth. She remembers her heart rate spiking, the gravel of the playground parking lot crunching under the car tires. He was crying and bleeding; the loose shards of his teeth she’d collected bit into her palm. She broke the speed limit getting him to the dentist’s office.

“It was my patch,” he said stubbornly, when he was all cleaned up. They were walking out of the waiting room; Daniel had brand new crowns on his two front teeth, made of artificial enamel and so neatly integrated into the roots that you couldn’t see the seams. The miracles of modern medicine.

“What was that?” She worried at the edge of the bandage on her palm—she’d gripped his chipped-off teeth so hard she’d bled. They put the pieces in a plastic bag to take home, if Daniel wanted them. He insisted he did.

“I fell ’cause of my eye patch, Mamãe,” he said. “So you should tell the doctor I have to take it off now.”

She stopped fidgeting. “It’s important to correct your vision while you’re young. Optometrist’s orders.”

“You always say that.” He gave her his best innocent face. “But do you want me to break off the rest of my teeth too?”

“Is that . . . a threat?”

“Yeah,” he said, angelic.

He didn’t win the eye patch war, but he earned himself an ice cream. She was privately relieved he wasn’t hurt too badly to scheme.

Her relationship with Daniel formed from moments like that, mundane and unforgettable. His sobs when he lost his favorite bath toy. The wide-mouthed smile he gave her, his lower teeth slightly crooked, when she let him stay up past his bedtime to watch old reruns of Caillou. The way he’d sniffle into her room after a nightmare, and she’d turn on the bedside lamp and read while he drifted back to sleep, curled warm and small against her side.

So she survived his childhood, and she savored it, too. Bitter and sweet.

---

On June 28, 2009, Stephen Hawking hosted a Time Traveler’s Party, sending out invitations the day after the event. The idea was simple: if the invitations survived until the invention of time travel, a traveler could have come back and joined Hawking for the celebration. None did.

Iara used to tell Teresa it was a joke. “It’s a compelling idea, of course,” she said. “But no successful time traveler in their right mind is going to show up to a thing like that. You’re just asking for a paradox.”

This was early in their relationship, when Teresa was still getting her PhD and barely starting to wrap her head around the fledgling field of temporal “science.” Most of the sites Teresa worked with involved human activity at least a few thousand years old; Iara would luxuriate in all the hypothetical havoc a careless time traveler to that period could wreak.

“Tell me again,” Iara said, “how irresponsible I’d be to travel all those centuries back.”

It was a sticky-hot day, and the two of them were lazing indoors. Iara was sketching absently, outlining the jaboticaba tree they could see through the window. She liked to draw plants, defining them by their negative space. Sometimes she’d ask Teresa to read to her while she drew.

Teresa trailed her fingers along Iara’s arm, a light touch. “Very irresponsible,” she said, taking a sip of her água de coco. “You’d have to make sure you were fully vaccinated. Not carrying any diseases you might accidentally introduce to pre-Cabraline society.”

“Mmm,” Iara tipped over to rest her head on Teresa’s shoulder. Her pencil scratched against paper, conjuring a cluster of fruit. “And what else?”

“Useful inventions travel like wildfire,” Teresa mused. “So . . . no teaching people how to write. You’d probably be safe speaking Portuguese or English if you went far enough back and kept it isolated. You couldn’t have children, of course, and if you stayed long enough to be near any, you’d have to keep modern languages from them, too. Just in case.”

“And all this to time travel ethically.”

“Not ethically,” Teresa said. “If you wanted ethical, you’ve got an argument for bringing tens of thousands of vaccine tablets for European diseases to distribute just before Cabral arrived. No, all this noninterventionist talk is just if you want to avoid changing the timeline and accidentally dooming us to death by paradox.”

“Nonexistence by paradox,” Iara suggested. “Or we could all get stuck in a never-ending iterative time loop equivalent to death and/or infinite torture. Theoretically.” She finished her drawing and signed it neatly, curling her name into itself.

“Sure,” Teresa allowed. “But death by paradox is snappier.”

She doesn’t begrudge that Iara used some of those ideas in later interviews. That the words “death by paradox” fell from her lips as smoothly as her comments on vaccination, quarantine, and language control as “proposed regulations for time travel.” It was back in the sound-bite days, when Iara was just trying to get enough traction to keep her research active. When she could use every bit of help she could get.

---

Teresa heard once that reading to children is important for their development, so she’s read Daniel to sleep since he was a baby. Not just children’s stories, but also articles on new radiocarbon dating techniques, on paleohistory, on her academic rivals’ newest archaeological claims. Call it multitasking. And sometimes, when she’s feeling particularly nostalgic, news clippings about advancements on Iara Cambaúva’s side of the academic world.

Around Daniel’s seventh birthday, the Matsuo team at the University of Tokyo achieves the first successful teleportation of a Drosophila fly from one side of the lab to the other. Journalists stop calling Iara’s theories pseudoscience.

Iara appears on some of the holopictures that accompany the articles. She’s let her hair grow out long again, the way Teresa used to like it. Teresa searches Iara’s name more often than she should. A compulsion, a scab peeled off anew with each click.

Iara’s getting closer, just like she always said she would. Bringing science fiction nearer to reality.

All this is on Teresa’s mind when she finds the next cave site. There, waiting for her, a new message. Written around two thousand years ago, just like the first: I love you. I miss you. I’m forgetting your face.

---

Teresa reaches out to her old PhD advisor, Dr. Michael Malkovich, in Canada. She tries to present the facts as comprehensively as possible. Tries not to come off like a kook.

His reply is brief. For the sake of your career, I’ll keep this between us. Have you considered seeing a therapist? -Mike

She’s not crazy. Her colleagues have seen the messages, too—and found them odd, though most assume they’re the work of a committed vandal. She brought up the pigment ages to two of them, who independently assumed there was infiltration of older carbon into the samples. But she knows. She knows.

They are nonspecific messages. They never call her by name. But they are, she does not doubt, for her. Even if she hadn’t known from the content of the messages, she’d know from Joseph’s question.

Dr. Joseph Osondu, a specialist in noninvasive imaging tech for human remains, is the only colleague who’s entertained the possibility that she’s right. And even he says he wouldn’t consider it for a second if he hadn’t met Iara.

“Even if your time traveler is real,” he adds after she confides—for once—in someone in her field who keeps up with Iara’s research, “Why only you? Why aren’t we all finding these messages?”

“Because she knows me,” Teresa says. “She knows where I do my work. What sites I’ve found. When she went back, she remembered. She’s following the same regulations she proposed: not writing names, nothing identifiable. But she’s writing in English and only targeting my sites. That’s evidence. That’s why it’s only me.”

Joseph nods, pensive. “She. Iara Cambaúva herself, you mean.”

Teresa nods. “And I can’t publish about it. I mean, if it is her, she’s reading my papers. That’s how she’ll know where to leave the messages. I can’t tip her off. The risk of paradox . . . ”

She pauses, trembling. She’s clenching her teeth so hard, a muscle in her jaw cramps. It’s too much: her career and her memories of Iara both rotting as she fails to disentangle them from each other. It’s just not like her. I never thought she’d do this to me.

“Let’s talk about something else, Teresa,” Joseph says, not unkindly. “Tell me, how is your son?”

She conjures a smile. “Good, good,” she manages. “He’s back in Canada now. He just picked up archery.”

---

Daniel doesn’t think she’s crazy, but then, Daniel is her son. He’s been with her at most of her sites over the years, usually reading at the campsite while she’s out in the field. When he’s fourteen, she catches him with Iara’s pop science book: Time and Time Again: Time Travel Theory for the Uninitiated.

“Where did you get that?” She reaches out to pluck it from his hands, and he twists it out of her grip, grinning.

“Borrowed it from the library. Don’t get jealous, Mãe.”

“Jealous?”

He shrugs, still smiling. “You’re just a little obsessed with her, is all. I wanted to see what the fuss was about. It’s a good book. She’s smart.”

He knows that she and Iara were married; he’s met Iara a few times. Teresa and Iara are civil. Teresa never tells Iara I know you’re stalking me from two thousand years in the past, because that would be impolite. But mostly because it might mean death by paradox.

Instead, when they cross paths, she has come to think—a little angry, a little sad—how could you make me live with this knowledge alone? It’s an honor. A burden. A secret. A glimpse of her ex-wife’s future, curled in Teresa’s cupped hands.

In any case, she’s been less subtle than she intends about Iara if Daniel has noticed. Though it’s not supposed to be easy to get over a woman you loved for nearly a decade. Is it?

---

She finds another message at that site, the end of the sentence smudged as if by a palm. I want to come home.

---

When Teresa zooms in on high-definition pictures of the messages, stored in the private folder of her phone, she thinks of the Kauaʻi ʻōʻō. It was the holdout survivor species of Hawaiian honeyeater in the late twentieth century: nectar-eater, cavity-nester, full-throat-singer. The bird was small, colored in shades of brown and black but for its bright yellow leg feathers. The song of the males and females twined together, a rising staircase of melody fluttering upward in tandem: call and response, echo and presence.

The last time the Kauaʻi ʻōʻō was spotted was in 1985. The last time it was heard came two years later. The naturalist who recorded the sound captured a single male ʻōʻō’s song. The audio file cradles one half of a melody, a broken climb, calling and calling.

The time traveler could be messing with Teresa, traveling back and forth in time to leave the messages, but they don’t read like that. They read like something happened. Like Iara got stuck. It reminds Teresa of the recording of that calling bird, so lonely, isolated from any hope of speaking to its kind again.

No response. No harmony. Nothing but that half-song, and absence.

---

Teresa met Iara on her second time in Brazil. It was Carnaval—not a holiday so much as a monthlong fete, as her Brazilian colleagues explained it. She’d allowed João to drag her down to meet a few of his friends from university.

Iara was just about Teresa’s height, throwing back caipirinhas with true Carnaval spirit. She had a bright laugh and deep brown eyes that flashed with intelligence. She pulled Teresa into her orbit like a sun.

A flash in the pan of attraction, heartbeats in throats, hands on hips, the dance floor and the caipirinhas and ringlets bouncing and a keen smile in the half-light. That was how it started. Teresa still can’t believe that’s how it started; it’s so unlike her, to act on impulse like they did that night. Perhaps it was their future selves, calling out, winding the threads of their lives into a tapestry.

Later, at Iara’s place, Teresa asked if it was true that Iara was some kind of time travel whiz.

Iara pulled back, touch dancing along Teresa’s collarbone. “Who said that?”

“João. Is it true?”

“Maybe,” Iara said—easily, though her fingers tensed against Teresa’s skin. “Are you going to insult me about it?”

Teresa shook her head. “I want to know what’s so genius about you,” she said. “Give me a basic idea. For a newbie.” Her cheeks were warm from drink and weather. Everything tasted sweet.

“If you ask,” Iara said, “you have to listen.”

“All right. I’m listening.”

“Okay,” said Iara. “If you time-traveled back to exactly one hour ago, to this very spot. Bum. Where would you be?”

Teresa snorted. “I’m not that tipsy,” she said. “Here. In this room.” She snapped her fingers. “No. Here alone, because we weren’t here an hour ago.”

“No, we weren’t,” Iara said. “And neither was the room.”

Teresa’s thoughts wobbled, tipped over, and tumbled in disarray. She began to collect them again. “Yes? It was?” she ventured.

“This house was on Earth, yes. But Earth’s always moving. We orbit the sun at almost thirty kilometers per second. You time travel to exactly this spot one hour ago, and you’re dying in the vacuum of space, linda. So if you want time travel, you’d better be ready to calculate a teleportation trajectory, too.”

It was that conversation that did it, Teresa often thought, though she and Iara didn’t get together for four more months. Teresa had stumbled back to work, abashed and hungover, the next morning. It took a chance meeting at one of João’s churrascos weeks later for them to exchange numbers. But Teresa hadn’t forgotten the time travel scientist with the gentle hands, the raspy laugh, and the stories of dying a painful space death.

---

She’d always thought she’d make a home with Iara. No, not just make a home; keep it. Not just make a family, but love it.

Daniel was supposed to be theirs. Not just hers, to raise as best she could alone.

There are times (more than she likes to admit) where Iara’s absence looms like a physical thing. Like when Teresa misses Daniel’s archery competitions every so often for work—or, on one never-repeated occasion, when she wrote and addressed and entirely forgot to send out the invitations for his ninth birthday party. He sequestered himself in his room after that for the span of his disappointment, and she felt an old familiar pang—like when she’d forgotten to call Iara on their anniversary because she’d been attending a conference.

Teresa hates that feeling. She will fight tooth and nail to keep from feeling—from being that way again.

Oh, how she envies most of the parents she knows, people with partners to share the responsibilities of raising a child. Parenthood is a juggling act for everyone, but she’s wrangling twice the load.

She just hopes that when she drops the balls, she picks them up again fast enough that nobody notices.

---

When Daniel is seventeen, he breaks his arm skateboarding the night before their flight back to Canada. Despite years of living and working part-time in Brazil, Teresa’s never been to an emergency room here. She’s not sure what to expect.

She could call a colleague for advice. Most of them live nearby.

Iara picks up on the second ring.

Thirty minutes later, Iara’s at the hospital. They all exchange small talk. Daniel was supposed to have an archery competition in two weeks; that’s off the table. While he’s in the bathroom, Iara tells Teresa he’s looking nice and healthy, acting very polite, getting to be handsome. “He must be going on so many dates already,” she says.

“Stop teasing.”

“No, really,” Iara says. “I haven’t seen him in years. He’s gotten tall.”

“Tall, yes.” Teresa says. “That’s not all that’s changed. You know, he thinks you’re a celebrity now. He read your book.”

Iara hums, pleased. “The boy has good taste.”

“He’s top of his physics classes—I think he might go into the teleportation field. I see him paging through those 3D schematics sites sometimes.”

Iara nods. “And you?”

“Me?”

“Did you read my book?”

Teresa’s saved from having to answer when Daniel returns. He eagerly picks up the thread of conversation now that it’s turned to Iara’s research, probing her with questions about how close she and her lab are getting to a functioning time machine. She swears him to secrecy and says they think they’ll get a prototype to a test phase within the decade.

“Wow.” Daniel grins. “That’s so much cooler than my mom’s work.”

“Daniel!”

Iara laughs. “Como ‘tá teu português, Daniel?”

“Muito bom. Eu falo melhor do que eu escrevo.”

“Nossa!” Iara gives Teresa an approving look. “Reach out to me if you’re ever looking for an internship,” she tells Daniel. “If you’re half as smart as your mother, I’m sure we can find a place for you.”

Daniel doesn’t talk about the offer on the plane. That’s how Teresa knows he’s taking it seriously. When he’s thinking hard, he goes quiet. She does the same.

Her son doesn’t look much like her. But he’s like her in all the ways that count. She gets flashes of that, of what Iara must have had to put up with: the way he’ll get so single-mindedly focused on his own life that it feels like he’s hardly listening when she talks. How he’ll fixate on an idea and turn it over from all angles, captivated by the implications. The way that once he reaches a decision, he can’t be swayed by anything short of an act of God.

Yes. He’s like her in all the ways that count.

---

She finds one more message at one more site. This time, there are only a few letters left, the rest degraded by smoke, the content unreadable. Teresa goes out into the mata after they finish up for the day, watching her step for snakes, and lets the sounds of the forest wash over her. The constant vocalizations of insects, a susurrus punctuated by louder clicks and hums and buzzes; the rustle of leaves, the calls of birds.

It’s supposed to clarify, to soothe, to wipe away the fact that it takes this message—this message she can’t read—to start to grieve what she hasn’t yet lost.

---

She remembers verbatim the last thing she said to Iara before the divorce. She’s turned those sharp words over in her head until their edges smoothed like sea glass.

They were sitting on a bench, looking out at the Atlantic Ocean. A visit to the coast—Jericoacoara, Teresa thinks, on a weekend she’d carved out from a busy schedule. She’d taken a call from a collaborator about a review, just five minutes of interruption. Iara’s hair was limned by the sunset when Teresa hung up, the planes of her face catching the light.

“Meu amor, this isn’t working,” Iara had said. “I don’t want to raise a family this way.”

She’d spoken calmly. That was the worst part, the calm. Iara could get heated so easily. Teresa found it endearing: the passion as Iara yelled at the screen during Imperatriz games, the way she’d get up in arms about the minor injustices of the world. And now, when their whole marriage was falling apart, as she described the cracks in their relationship like a study in shattered glass, all that endless energy was gone. Ground out, made dust.

Teresa aimed not to sound pitiful; she overcorrected into accusation. “We were about to start trying.”

“You’ve been saying that for three years now.”

“We were. We have the doctor’s appointment—”

“We’ve had that doctor’s appointment for almost as long. You’re the one who keeps pushing it back for your research. Meu amor, I don’t want to argue. You put what you want first and assume the rest will work out, and you’re too prideful to ask for help when it doesn’t. Te amo, pra sempre. Mas, acabou.”

It’s over? Teresa’s cheeks were hot with embarrassment. Maybe terror. It’d been eight years since she lived a life without Iara in it. “You’re going to regret it,” she said viciously. “You think your pipe dreams are enough to keep the money flowing? Like one of those machines would ever work. You’ll regret leaving me. I swear to God. I swear to God you’ll miss me.”

Iara nodded, face placid as a lake. “I think you could use some time to calm down,” she said, and she stood up and walked away.

You were right, the first message had said. I miss you.

It was supposed to feel better, those words a salve laying that old conversation to rest, but there was still a hole in Teresa’s chest where the pain lived. It didn’t help to know that somewhere in the future, Iara was going to climb into a time machine and trap herself two thousand years in the past. It didn’t help to know she’d sought out Teresa’s archaeological sites and told her she was right, finally. Because they’d divorced eighteen years ago, so it was already too late.

---

She will never tell Iara she decided to become a single mother the week after the divorce was finalized. That she did it to prove to Iara that she could. To prove the same thing to herself.

She will certainly never tell Daniel that sometimes she worries Iara was right.

---

None of it matters anyway. In the end, Daniel picks Iara.

He certainly doesn’t think of it that way when he tells Teresa he’s choosing to apply to Iara’s home institution in Brazil for university. He intends to take her up on the internship offer. He’ll major in physics, with a focus on temporal science.

---

Iara once told Teresa she decided to work in temporal science because of “Flying Machines Which Do Not Fly,” a 1903 New York Times editorial that claimed it would be millions of years before man soared, birdlike, through the air. The Wright brothers took flight at Kitty Hawk before the year was out.

“In all ways but physical, it’s 1903 for time travel,” Iara had said, a smile lighting her face. “I love unsolvable problems. I love the puzzle of it.”

Teresa understood—it was the same reason she’d fallen for archaeology. There was such satisfaction in piecing together the past from the traces it left. The stories told by presence and absence, patterns and disarray. She spent hours in high school solving crossword puzzles and logic games, loving the cumulative crest toward resolution. Her research gave her the same buzz.

Perhaps that was why she’d thought she and Iara approached their work the same, too. Why she was surprised, embarrassed, almost upset to realize in the aftermath of the divorce that Iara had not. Iara had made not just minimal, but ample space for their marriage. She had done it invisibly, or rather, so naturally that Teresa had never noticed.

Teresa should not feel blindsided by Daniel’s decision. And yet she feels as though, for all that she has tried not to fall into old habits, fighting so hard not to compromise on motherhood or archaeology, at some point she has lost him.

Perhaps, she thinks, as she sees him off at the airport for his first semester, every parent feels this way; perhaps it is not so much losing her son as letting him go off to find himself.

She can’t quite make herself believe it.

---

As an empty nester, Teresa throws herself back into her work. It’s been a long time since she was able to thrust everything else aside and give her all to her profession; Daniel prevented that kind of schedule, and before that, Iara. But now she can do what she once did: devote herself with the fervor of an acolyte.

It doesn’t feel like it used to. She’s no longer as tireless as she once was. She’s excited to work, yes, but when she comes home and the house is dark, she finds herself listless at the kitchen table, skimming through papers without comprehending what she reads. She moves restlessly in bed, throwing one leg over the sheets before tucking it beneath them again, and stares at the ceiling in the dark with dry eyes.

She’d thought the work would be the same as it was before. But absence has a presence.

She should know that by now.

---

Teresa gets Joseph’s ping a few nights before Daniel’s first semester ends. Just uncovered a grave site. One skeleton doesn’t fit.

She has to put down her phone. Steady herself. She replies, just two words. It’s her?

Don’t quote me, Joseph messages, a self-deleting text so she knows he means it, but I believe so.

---

She’s not supposed to be here. She’s not registered for the site. But she and Joseph go way back, and she drove half the day to make it. He brings her in when it’s dark, and the rest of the crew has gone home. It’s muggy out here, humid, and she tucks damp strands of hair behind her ears as she follows him to the site. Her headlamp light wobbles on the ground; she’s a sailor on uncertain seas.

She feels nauseous. She’s about to see proof that sometime in the future, the great Iara Cambaúva crossed a boundary in time and couldn’t return. That she went to the past and died there.

“I did some basic scans on the skeletons,” Joseph says, guiding her around posts in the ground marked by neon ties. “This one had some anomalies.”

“What kind?”

“The age of the bones is contemporary with the other human remains,” Joseph says, “but there’s medical work consistent with modern technology. It’s here.”

He points to a skeleton, half uncovered. Nothing more than bone, now; of course, Teresa expected that. The empty eye sockets are filled with rich, dark soil. She squats—oh, her poor knees—and examines it. It’s illuminated by her headlamp, casting strange shadows that make it look too big for the woman she knows it belongs to.

“You can’t see the dental work very well without the sensors,” Joseph continues, “but on the left ulna, there was a healed transverse fracture. You might be able to spot it?”

Teresa freezes. Her heartbeat is slow, steady, but she does not breathe.

“Did you say dental work?”

“Yes.” Joseph taps on his tablet. “Our scans showed artificial enamel crowns on the two front teeth.”

---

You were right. I miss you. I’m forgetting your face.

I want to come home.

---

She picks Daniel up at the end of his semester, crashing from finals and ready for a break. He’s talking about school, and girls, and his plans for video gaming over the holidays. She can’t bring herself to look at him. She keeps remembering his skeleton instead, degraded by two millennia, the eye sockets empty.

Death by paradox or death two thousand years ago. It’s a closed loop. She can’t stop it.

Daniel didn’t need to read all her papers to know where she worked; he’d been there with her. She should’ve realized. Every site she’s found a message at is one to which she’s brought her son.

Joseph pings her, asking if she wants to know the estimated age of the time traveler when they died.

Teresa says she does not.

---

Daniel is oblivious. He is walking into his own noose. He’s like she once was in all the ways that count, which means once he reaches a decision, he can’t be swayed by anything short of an act of God.

She’s not God. God wouldn’t be bound by something so trivial as a paradox. Daniel walks into the kitchen barefoot one morning on his break, his dark hair mussed, scratching at his chin. It’s so tempting to say something to him, anything. “Stop working with Iara.” “Don’t use the prototype.” “Wherever it is you want to go, know you won’t come back.”

But she can see the trap waiting for her, and as much as she wants to, she can’t make herself step in it.

She thinks she might have, once, when she was young; tell him and damn the consequences, if she still existed to experience them.

Instead, she wrinkles her nose and flicks her spatula at him. “Deodorant, Daniel, now. Jesus, I can smell you from here. I say this because I love you.”

“You say this because you love making me suffer.” He grins. “Don’t make that face, Mãe, it’s fine, I’m going.”

He’s back a few moments later, smelling much better, and as they’re eating pão de queijo and açai, she manages to sink into the moment enough to forget. You can do this, she thinks, steeling herself. You do what you can without tipping him off, and nothing more. At least you know.

She can’t decide if that’s better or worse.

---

She buys a time capsule. It’s roughly the size of her thumbnail, about two grams in weight. State-of-the-art tech that promises to record and maintain a message for hundreds of years. Hundreds, not thousands, but there’s nothing better on the market; she’s looked.

She gives it to Daniel the next time she’s in Brazil, corded onto a thin metal chain, and makes him promise to wear it—not use it—until his next birthday. “I have my reasons,” she says, forcing a smile. If he’s still in the late twenty-first century by the time he turns twenty, she’ll reassess. For now, it’s the best she can do without telling him what it’s for.

She does this and one more thing. She drives him out to a field site.

It’s a small alcove, barely a cave. Not too far to trek from the nearest road. The paintings they thought they’d discovered here turned out to be graffiti from the 1900s, not evidence of pre-Cabraline human presence. She hasn’t been back in more than two decades.

“A site?” He rolls his eyes. “Come on, Mãe, I’ve been to a million of these.”

“Not this one,” she says. The chain of his new necklace dangles beside the one for the cross he’s worn since he was a teen. Both pendants are hidden beneath his shirt. She hopes he forgets to be annoyed by it. She hopes he never takes it off. “Look up there,” she says, pointing. “See that rock?”

“It looks like a . . . ” he trails off with a snort.

“Yes, it’s rather phallic,” she says. “We joked about that when I was a student. Makes it memorable, though, doesn’t it?”

“I guess.”

“Here. Look at this.” She points out the graffiti, shows him why they’d thought someone might’ve used this cave for shelter millennia ago.

And then she drops to one knee beneath the rock and puts her hand on the ground. “Come here,” she says. He does, reluctantly. She tries to keep the urgency out of her voice, but she needs him to remember this. She’s deliberately trying to make it awkward and strange. Trying to make it stick. “Put your hand here.”

“On the dirt?”

“Yes, on the dirt.”

He wrinkles his nose but obeys.

“No one’s dug here for thousands and thousands of years. Do you understand that, Daniel? This land has been untouched for all that time. Unchanged. That rock might be more weathered now, true, but it probably looked just as much like a dick two thousand years ago as it does now. Do you hear what I’m saying?”

He snorts again when she says dick, but when she’s done, he schools his features to seriousness. “Sure.”

“Okay.” She stands up, brushes off her hands. “I love you. You know that, right?”

He says of course he does, and he hugs her, but his mind is not with her at the site. He’s thinking of something else. Somewhen else. She can see it in his eyes.

At least, that’s how it always looked in hers.

---

That’s all she can do. Anything more, and she’d risk the paradox.

So she puts her energy elsewhere. She makes time for him. Calls him, picks up when he calls her. He’s often distracted on the phone, walking between classes or just getting out of lab. He plays soccer most days. He made friends with the guy who works as the school’s raccoon mascot. He’s dating a girl from Ilha do Combú, just across the Rio Guamá.

Teresa soaks in the details of her son’s life over the phone. She finds two more brief and cryptic messages among her sites. Each one pricks her heart with fondness.

“Miss you, love you, be careful,” she tells him at the end of their calls, and she knows he thinks she’s talking about safe sex. She is, to be fair—she’d prefer he not get stuck with an STD. But that’s not all she means, and someday he’ll realize it.

It’s strange. She’s loving her son in two directions. She’s loving him now. She’s loving him backward, across centuries.

---

It’s muggy, humidity clinging to her clothes and skin and hair, on the day her call doesn’t go through. She dials again. No answer, no text response.

She calls Iara.

“Sorry, Teresa, can’t talk long,” Iara sounds winded, breathless. “Power’s out.”

A sinking feeling in Teresa’s stomach. “How bad?”

“All of it, out to Marambaia. The whole grid. Nothing but generators still working.” Iara laughs harshly. “Meu Deus. I don’t know who fucked this up, but whoever it is—”

“Where’s Daniel?”

“Daniel? At the lab, as far as I know. Why?”

Teresa puts her head in her hands. She does not respond for one moment, two. “Iara,” she says, “if someone were to use the prototype in your lab, could it cause that outage?”

There’s silence on the other end of the line. They could sometimes communicate like this when they were married; Teresa supposes they still can.

Iara doesn’t say another word before she hangs up. She doesn’t have to.

---

When it’s confirmed—Daniel gone, the machine still smoking—Teresa tells Iara everything. From start to finish. First message to the gift of the capsule.

“Puta que pariu. All right,” Iara says. “Stay where you are. I’m coming.”

She picks Teresa up. She’s in the same car she used to drive Daniel and Teresa to the airport after he broke his arm. Teresa feels the absence in the back seat.

“Do you have a shovel?” Iara asks.

Teresa nods.

“Flashlights?”

“Yes.”

“Metal detector?”

“I brought two.”

Iara starts driving to the site with the graffiti. She doesn’t ask for directions. She always did have excellent spatial memory. She knows the way to all of Teresa’s field sites as thoroughly as every dark and unsavory corner of Teresa’s heart.

Teresa presses her cheek against the window. The scenery flicks by, green and brown. “I thought I had come to terms with this,” she murmurs.

“You didn’t warn him,” Iara says. There’s no judgment in it; a hint of a question, maybe.

“I couldn’t. The paradox.”

“You wanted to, though.”

“More than anything.” Teresa shudders. “I wanted to tell him so, so badly. I wanted to keep him safe even if it meant we might all die.”

“Hmm. Why didn’t you?”

Maybe she’s a traitor. A terrible mother. A broken human, not to ruin the world trying to save her son.

“It would have been for me,” Teresa says. “I would’ve either driven him into a paradox or doomed him to know his fate and not escape it. If I told him, it wouldn’t have been for him. Just for me.”

The sun is setting, the familiar landscape cast in shades of gold. She watches a bird take flight just off the road, flying parallel to the car for a few moments before it veers off to an unknown destination.

Teresa swallows. “I called you because if he remembered what I said and recorded a message and buried it beneath that rock, it’s waiting there for me. It’s been waiting there our entire lives. We didn’t even know it. When you and I hiked out to that site for the first time together, it could’ve been under our feet.”

She scrubs her eyes with the heel of her palm. “And I called you because he should’ve been ours from the start. I can’t do it all by myself, Iara. I don’t want to.”

Iara does not look away from the road, but she reaches out one hand and sets it on Teresa’s thigh. It’s warm. Grounding. Iara says nothing, but when Teresa twines their fingers together, she doesn’t pull back.

---

The site is just as Teresa remembered it, though it’s getting dark. When she turns on the metal detector, it chimes, a clear tone repeated. It’s high-sensitivity, research-grade. It chimes faster with proximity. It should detect anything buried to the depth Daniel would’ve been able to manage two millennia ago.

They reach the rock. Teresa sweeps the detector across the bare spot where she’d knelt with Daniel, listening to the rhythm of its chime. Nothing changes.

“There might’ve been plant growth there at the time,” Iara says softly. “Let’s do a sweep. I’ll take the east side, you take the west. And if it’s not here, Teresa, it could be at another site. We’ll check them all if we have to.”

Teresa nods. She starts to walk, sweeping the detector over the ground in front of her. She listens to the steady chime. The air hangs humid around her, cloying. The night insects are starting to sing.

She walks, the chime a call of her own. Somewhere behind her is her first and last love. Somewhere in front might be the first and last recording of her son.

One half of a melody, waiting for the rest of the song.