The lecture hall was half-empty, which wasn't unusual for an 8 AM quantum mechanics class on a Friday.
Kael Thorne stood at the whiteboard, marker in hand, trying to explain the concept of quantum entanglement to seventeen undergraduates who looked like they'd rather be anywhere else. He didn't blame them. At their age, he'd felt the same way about early morning classes.
"So when we say two particles are entangled," he continued, drawing a diagram that probably looked more confusing than helpful, "we mean that measuring the state of one particle instantaneously affects the state of the other, regardless of the distance between them. Einstein called it 'spooky action at a distance.'"
A hand went up in the back row. Sarah Chen, one of his better students. "But Professor Thorne, how is that possible? Doesn't that violate the speed of light limit?"
"Excellent question." Kael turned back to the board, then felt the familiar wave of fatigue wash over him. Not now. He'd taken his medication this morning. It should have lasted at least until noon.
He gripped the edge of the desk, steadying himself. The moment passed. He took a breath and continued. "It doesn't violate relativity because no information is actually being transmitted. The particles are correlated, but you can't use that correlation to send a message faster than light"
The door burst open.
Dr. Marcus Webb exploded into the lecture hall like a force of nature, his red hair sticking up in every direction, his lab coat covered in what looked like coffee stains. He was grinning like a madman.
"Kael! You have to see this. Right now. It's incredible. I mean, truly, fundamentally, universe-alteringly incredible"
"Marcus." Kael's voice was quiet but firm. "I'm teaching."
Marcus finally seemed to notice the seventeen pairs of eyes staring at him. "Oh. Right. Sorry." He looked at the students. "This is way more important than quantum mechanics, though. No offense to quantum mechanics."
Several students laughed. Kael pinched the bridge of his nose beneath his glasses. This wasn't the first time Marcus had interrupted a class, and it wouldn't be the last.
"I'll be there in twenty minutes," Kael said. "We're almost done."
"Twenty minutes might be too late. The cellular degradation could"
"Marcus."
"Fine. Twenty minutes. But I'm timing you." Marcus checked his watch dramatically, then left as chaotically as he'd entered.
The students were grinning now, the earlier boredom replaced with amusement. Kael sighed. "That was Dr. Webb. He's a geneticist. And yes, he's always like that."
"Is he your friend?" Sarah asked.
"Unfortunately." Kael's dry delivery got another laugh. "Now, where were we? Right. Quantum entanglement and the Einstein-Podolsky-Rosen paradox..."
He managed to finish the lecture, though his mind kept wandering to whatever Marcus had discovered. His friend's enthusiasm could mean anything from "I successfully grew bacteria in a petri dish" to "I've accidentally created sentient mold." With Marcus, you never knew.
When the students filed out, Kael gathered his notes slowly. The fatigue was getting worse. He'd need to sit down soon, maybe take an extra pill even though his doctor had warned him about exceeding the daily dose.
The condition didn't have a cure. Mitochondrial myopathy, the doctors called it. A genetic disorder that affected his cells' ability to produce energy. Some days were better than others. Today was trending toward "other."
He made his way across campus, moving at a pace that wouldn't exhaust him but also wouldn't look too slow. Pride was a stupid thing to cling to, but he clung to it anyway. He'd spent his whole life being "the sick kid," "the weak one," "Aaron Thorne's disappointing son." He'd be damned if he'd let anyone see him struggle more than necessary.
Marcus's lab was in the biology building, tucked away in a basement corner that the university had forgotten about. After Marcus's "incident" at the major research institute three years ago unauthorized human trials, ethics violations, the whole mess he'd been lucky to keep any lab space at all. The university had given him this dungeon as a courtesy, probably hoping he'd quit.
Marcus had turned it into organized chaos. Equipment covered every surface centrifuges, microscopes, incubators, and machines Kael couldn't begin to identify. The walls were covered with diagrams, formulas, and sticky notes with incomprehensible abbreviations. A half-eaten sandwich sat next to what looked like a DNA sequencer.
Marcus was hunched over a microscope when Kael entered. "Finally! I was about to come drag you here myself."
"You interrupted my class eighteen minutes ago."
"Felt like an eternity." Marcus gestured excitedly at the microscope. "Look at this. Just look."
Kael looked. The slide showed cells human cells, from what he could tell, but there was something odd about their structure. The mitochondria were... different. Larger. More complex.
"I don't know what I'm looking at," Kael admitted.
"Of course you don't. You're a physicist." Marcus pulled up a chair the only clean one in the lab and practically shoved Kael into it. "Those are your cells."
Kael's stomach dropped. "What?"
"From the blood sample you gave me last month. Remember? For the baseline analysis?" Marcus was pacing now, gesturing wildly. "I've been working on a modified gene therapy approach. The problem with your mitochondrial myopathy is that your mitochondria can't produce enough ATP"
"I know what the problem is, Marcus."
"Right, right. But what if we could enhance your mitochondrial function? Not just fix it, but improve it beyond normal human capacity?" Marcus pulled up a computer screen showing complex genetic sequences. "I've been studying extremophiles organisms that survive in impossible conditions. Tardigrades that can survive in space. Deep-sea bacteria that thrive near volcanic vents. Their cellular structures are incredible."
Kael felt a familiar mix of hope and dread. They'd had this conversation before, in various forms, for the past fifteen years. Ever since they were kids and Kael had collapsed during a soccer game while Marcus watched helplessly from the sidelines.
"Marcus," Kael said carefully, "we've talked about this. Gene therapy for mitochondrial disorders is still experimental. The risks"
"Are worth it," Marcus interrupted. "Kael, you're thirty years old and you can barely make it through a day without exhausting yourself. You take medication just to function at half the capacity of a normal person. And it's getting worse. We both know it's getting worse."
The words hung in the air. They were true, and that made them hurt more.
Kael looked at his hands. They were trembling slightly not from fear, but from the constant low-level exhaustion that never quite went away. "What are you proposing?"
"A single injection. Modified genes that would integrate into your cells and enhance your mitochondrial function. I've tested it on cell cultures your cell cultures and the results are remarkable. ATP production increased by 300%. Cell regeneration improved. No signs of rejection or adverse effects."
"In a petri dish," Kael pointed out. "That's not the same as a living human."
"I know." Marcus's voice softened. "But Kael, this could work. This could give you a normal life. Maybe even better than normal."
Kael wanted to believe it. God, he wanted to believe it so badly. To wake up without feeling like he'd already run a marathon. To teach a full day of classes without needing to sit down every thirty minutes. To not have to plan every activity around his energy levels like a miser counting coins.
To not be weak.
But he'd learned, over thirty years of disappointing diagnoses and failed treatments, that hope was dangerous.
"I need to think about it," Kael said finally.
Marcus's shoulders sagged. "How long have you been thinking about it? We've had this conversation a dozen times"
"And my answer is the same every time." Kael stood, carefully, making sure his legs would support him. "I appreciate what you're trying to do. I do. But I'm not going to be your test subject for untested gene therapy, no matter how promising it looks under a microscope."
"You're being stubborn."
"I'm being careful. There's a difference."
Marcus looked like he wanted to argue more, but something in Kael's expression stopped him. They'd been friends too long. Marcus knew when to push and when to let it go.
"Fine," Marcus said. "But the offer stands. Always."
"I know." Kael headed for the door, then paused. "And Marcus? Thank you. Really. I know you're trying to help."
"Someone has to. You certainly won't help yourself."
Kael left before Marcus could restart the argument. He made his way back across campus, the afternoon sun warm on his face. Students rushed past, full of energy and life and futures that stretched out before them without limits.
He tried not to be bitter about it. He'd mostly succeeded over the years. But some days were harder than others.
His apartment was a twenty-minute walk from campus too far when he was this tired, but he'd never bothered getting a car. He told himself it was an environmental choice. Really, it was because driving while exhausted seemed like a bad idea.
The apartment was small but comfortable. One bedroom, a living area that doubled as his home office, a kitchen barely big enough to cook in. The walls were covered with bookshelves, every surface crammed with physics textbooks, science journals, and the occasional novel. A desk sat by the window, covered with papers his father's old research notes, which he'd been slowly working through for the past two years, ever since his father's death.
Dr. Aaron Thorne had been a brilliant astrophysicist. Everyone said so. Kael's mother had said so. His colleagues had said so. The obituaries had said so.
Kael barely remembered him.
He'd been seven when his father disappeared. Just... vanished one day. No body. No note. No explanation. The police had investigated, found nothing, eventually declared it a cold case. His mother had never really recovered from it. She'd died when Kael was fifteen, and he'd always wondered if the grief had contributed to the illness that took her.
His father had reappeared briefly for three days when Kael was sixteen. Older, weathered, speaking in vague terms about "breakthrough research" and "being somewhere he couldn't leave." He'd hugged Kael, apologized for abandoning him, and promised to explain everything someday.
Then he'd disappeared again.
He'd died two years ago. A heart attack, sudden and unexpected. By then, Kael had been almost relieved. At least death was final. At least he could stop wondering if his father would walk through the door with another inadequate apology and another vague excuse.
The only thing his father had left behind was boxes of research notes. Equations about wormholes and quantum tunneling. Theoretical physics that seemed more like science fiction than science. Kael had been working through them in his spare time, trying to understand what his father had been chasing that was more important than his own son.
He sat at the desk now, pulling out the latest notebook. His father's handwriting was neat, methodical. The entries were dated this one from twenty-four years ago, right before he'd disappeared the first time.
March 15th: The calculations are complete. The wormhole is real. Stable. Predictable. It opens during specific magnetic and gravitational alignments. I've built a detector to track the pattern.
I know I shouldn't go through. This is unprecedented. Dangerous. But the opportunity... how can I not? How can any scientist see a door to another world and not walk through it?
I'll be back in a week. Two at most. Just long enough to document what's on the other side. Elena will understand. Kael is young he won't even remember I was gone.
Kael's hands tightened on the notebook. "I remembered," he said to the empty apartment. "I remembered every single day you were gone."
He kept reading.
March 16th: I'm going tonight. The alignment is perfect. I've left instructions for Elena in case something goes wrong. The detector is in the lab. The coordinates are in my safe. If I don't return within two weeks, she should contact Harrison at the university.
The entry ended there. The next entry was dated three years later, when his father had briefly returned:
April 2nd: I've failed them. All of them. I thought I could get back. I tried for three years every time the wormhole opened, I was there. But it never appeared in the same place on Earth. I'd emerge thousands of miles from home. By the time I found my way back to Kael and Elena, the wormhole had closed again.
I've seen Kael. He's grown so much. He barely recognizes me. Elena won't even look at me. I've destroyed my family for the sake of another world.
But I can't abandon Teravyn either. They need me. The civilizations are fracturing. Without someone to mediate, they'll tear themselves apart.
I have to go back. God forgive me, I have to go back.
Kael closed the notebook. He'd read these entries before, but they never got easier.
Teravyn. His father had mentioned that name repeatedly in the later notebooks. A world with four civilizations based on elements. A world where his father had somehow become a king.
It sounded insane. But the calculations in the notebooks were real. The physics was sound, even if it was far beyond anything currently accepted by mainstream science. His father had discovered something. Something real.
Kael had been trying to recreate the detector for months. The device that could track when and where the wormhole would open. If he could build it, if he could find the pattern...
What would he do? Go through? Confront his father's memory in the world he'd chosen over his own son?
He didn't know. But he needed to understand. He needed to know what had been worth losing everything for.
His phone buzzed. A text from Marcus: Sorry about earlier. Pizza tonight? My treat.
Kael smiled despite himself. Marcus might be pushy and ethically questionable and occasionally infuriating, but he was also the best friend Kael had ever had.
Sure, he texted back. But no more gene therapy talk.
No promises, Marcus replied immediately.
Kael set his phone down and turned back to his father's notes. Outside, the sun was setting, painting his apartment in shades of orange and gold. Somewhere in the city, life continued. People went about their evenings, unburdened by mysterious disappearances or chronic illness or the weight of legacies they never asked for.
Kael envied them.
But he also wouldn't trade places with them. Because despite everything the pain, the exhaustion, the unanswered questions he was still his father's son. And that meant he was curious. It meant he needed to know.
It meant that if there really was a door to another world, he would walk through it.
Even if it destroyed him the way it had destroyed his father.
He pulled out a fresh sheet of paper and began sketching a new design for the detector. The equations flowed from his pen, elegant and precise. This was what he was good at. This was where he belonged not in the world of strength and endurance, but in the world of thought and theory.
If he couldn't be strong in body, he would be strong in mind.
It would have to be enough.
Outside, the first stars appeared in the darkening sky. Somewhere among them or perhaps not among them at all, but somewhere perpendicular to them in a way that defied normal geometry was Teravyn.
The world his father had chosen.
The world Kael was determined to understand.
Even if he didn't yet know that in three days, that world would come crashing into his life in the form of a desperate, dangerous, impossibly brave girl who thought he was someone worth attacking.
Even if he didn't yet know that everything he thought he understood about his father, about himself, about what it meant to be strong all of it was about to change.
For now, he just worked on his equations.
And the universe, indifferent as always, continued its slow rotation toward the inevitable collision.