Chapter Text
January 27th, 5757
Senku woke up.
The natural light filtered through the curtains he had forgotten to close completely the night before and hit his eyes directly. He grunted, turned over and buried his face in the pillow, hoping to get a little more sleep.
It didn't work. He was already awake.
He stayed there for a few minutes listening to the annoying buzzing of that broken fan he had been promising to fix for weeks. His internal clock marked seven, which was early but not early enough to consider it productive.
He opened one eye reluctantly, the white and unadorned ceiling was the first thing his blurry vision focused on. He contemplated it for a moment, allowing his brain to begin reorganizing the tangle of ideas he had left on pause when he fell asleep. It was like restarting a computer: slow at first, then gradually faster.
Sitting up slowly he scratched the back of his neck, feeling how his hair was a mess, more spiky than usual. Great. He would have to take a shower if he didn't want it to be an even worse mess later. With lazy movements, his gaze drifted toward the table next to the bed where some scribbled sheets full of formulas rested, a couple of screwdrivers, his laptop, along with his cell phone and a cup of cold coffee he never got to finish. It was the usual disorder of his work nights.
Senku stretched and his back responded with a couple of discouraging cracks but the pain slowly dissipated, replaced by that sensation of tense muscles reluctantly giving way. He yawned while pushing aside the wrinkled sheets getting out of bed, which was a mess and he stood for a moment, observing the disorder. He could tidy it up, but considering that same night it would be a mess again, why bother?
With a shrug he dismissed the idea and headed to the bathroom with carefree steps, but he had barely advanced two meters when his little toe crashed against the table leg with the force of a hammer, and the pain went through him like an electric shock that traveled from the tip of his foot to his spinal cord.
"Fuck!" he yelled, automatically jumping on one foot while grabbing the other as if that was going to stop the stabbing pain.
He grimaced while limping in small circles, cursing his luck and the existence of furniture in general even with the pain pulsing intensely, with an amount that seemed disproportionate for something as small as a toe.
"Damn table," he muttered through his teeth, limping the rest of the way trying to maintain all the dignity he could muster after such a morning spectacle.
Still rubbing his sore foot, he entered the bathroom only to immediately encounter the complete collection of elegant jars, imported creams and glass bottles that the mentalist had left scattered all over the sink surface as if it were his personal vanity. Senku rubbed his temples with weariness.
"Seriously, Gen..."
He pushed everything aside with brusque movements, lining up the containers in a corner without much care. A small bottle of lotion almost slipped from his hands and he caught it just in time.
"I'm definitely going to scold him for this," he muttered, making a mental note to add it to his growing list of complaints while opening the water faucet and pushing aside with his elbow a bottle of cream that was dangerously close to the edge of the sink.
He opened the top drawer with a routine movement and took his toothbrush, only to stop abruptly when examining the deplorable state of the object: the bristles were completely splayed open, and the back was covered with so many deep bite marks that it looked more like the favorite toy of a particularly destructive dog.
When was the last time he changed it? Well. The question answers itself upon seeing the deplorable state of the object. Without hesitation, he threw it in the trash with more force than necessary. The sound of plastic hitting the bottom of the bin was satisfying. He opened a new one, removing the packaging with quick movements.
He brushed his teeth with automatic movements and the minty taste cleared his mind a bit, though he still felt heavy and sluggish from sleep.
After rinsing, he headed directly to the shower and opened the faucet without waiting for it to warm up because waiting seemed like an unnecessary waste of time, and besides he needed the shock of cold water to clear his head completely. The icy sensation helped him wake up suddenly, eliminating the last traces of sleepiness that still remained in his body.
Coming out of the shower he felt considerably more human than five minutes before. He dried himself carelessly, running the towel through his hair until it was even more unruly than it was. He put on clean clothes and crowned the ensemble with the lab coat that Yuzuriha had given him for his birthday, the only one that was still impeccable despite the working hours it already had on it.
Ready, he took a quick look at his reflection in the bathroom mirror, he looked presentable, at least by his usual standards. And without bothering to have breakfast —his stomach could wait until he got to the lab—, he gathered a couple of important papers from the table along with the car keys and left the apartment closing the door behind him. He wasn't exactly a fan of driving and even less so with most streets of the modern world still unpaved, but driving had become the most efficient and reliable means of transportation available, so he resigned himself to accepting that daily reality. The laboratory awaited him and the growing anxiety to arrive and continue with his project far outweighed any discomfort the road offered him.
Because today they would finally test the time machine.
There were no guarantees it would work perfectly on the first try, but Senku had that stubborn hope stuck in his head: after months of work, the moment had finally arrived. The structure was complete, the energy source remained stable and all the formulas matched perfectly. In theory, everything was ready.
However, confidence in numbers was one thing, and dealing with human concerns was something completely different.
Not everyone on the team shared his enthusiasm. Senku had already lost count of the arguments he'd had lately. Chrome trusted science completely, but was terrified of any error that could occur in the test. Xeno had spent the entire last month suggesting "less valuable to humanity" candidates as test subjects.
Gen...
That had been the worst fight of all.
That probably explained why he hadn't seen him this morning. The mentalist had developed the habit of appearing in his room as if it were his house, but today he had been conspicuously absent. Only leaving his usual trail of beauty products scattered around the bathroom.
Senku gripped the steering wheel tighter than necessary. Dealing with that situation was also on his to-do list.
Because Senku didn't plan to back down at this moment. He wasn't so selfish as to put someone else at risk when he knew this project better than anyone. If something went wrong, he would be the one who could find the flaw and correct it.
At least that's what he hoped. Maybe with a bit of luck...
He chuckled remembering how Gen used to constantly complain that luck wasn't exactly his strong point. The mentalist was right, of course. Senku had spent his entire life relying on logic and hard data, not on uncertain probabilities.
But this time, he admitted to himself, a little luck wouldn't hurt.
With a sigh he parked his car in his assigned spot and got out, slamming the door behind him as he headed toward the large automatic doors while mentally criticizing Ryusui for sparing no expense to make the place look modern. Everything had to be state-of-the-art, even when half the world was still rebuilding.
He advanced down the hallway and stopped in front of the elevator. He pressed the button and waited, drumming his fingers against his leg while watching the numbers descend slowly. The building had eight floors, but the elevator seemed to take its time going through each one.
Finally, the doors opened with a soft ding and he got inside, pressing the button for the seventh floor where his laboratory was.
"Wait! Senku!"
He didn't need to look up to recognize Chrome's voice. Senku extended his hand and kept the button pressed to keep the doors open while the boy arrived panting toward him.
"I've been shouting at you since the parking lot, buddy," the boy puffed, getting into the elevator while breathing heavily.
"Why would you do that?" Senku snorted, releasing the button and letting the doors close. "We were going to see each other anyway."
Chrome straightened up, catching his breath.
"I ran into some scientists from the new program. Apparently, Xeno threatened them for not following his orders... and they asked me to tell you about it."
Senku frowned. Xeno threatening people wasn't exactly news, but scientists coming to complain directly was new.
"And Gen? He's the one who handles Xeno."
Chrome blinked, surprised by the question.
"If you don't know where he is, I certainly don't. Wasn't he staying at your apartment?"
Senku didn't respond immediately. The elevator doors opened with another soft ding, and he stepped out without saying a word. Chrome followed him, clearly expecting an answer.
Still frowning, Senku headed toward the laboratory. The slight buzzing of the automatic doors mixed with a murmur of voices on the other side. At least there were people working early, that was good. It meant they might be able to move faster than expected.
As the doors opened, the scene surprised and amused him in equal parts: Gen was already there, standing in front of Xeno and Stanley. With his arms crossed in a posture that Senku recognized as his professional mode. Apparently, the mentalist had already found out about the problem with the scientists from the new program, and now Senku was interrupting his scolding.
Chrome peeked over Senku's shoulder and let out a low whistle.
"Well, at least now you don't have to worry about where he was," he murmured, clearly relieved not to be the one who had to deal with the situation.
Gen looked up when he heard the soft buzzing of the automatic doors opening. His eyes met Senku's for a brief moment, before the mentalist deliberately turned his attention back to Xeno, completely ignoring Senku's presence.
What caught Senku's attention most wasn't the situation itself, but the mentalist's attitude. He remained confident while tapping Xeno's chest with one finger, and although it was clear he was furious, he spoke with that perfectly controlled tone as always. A completely different version of the Gen from the night before, when Senku had seen him break down to tears.
He shook his head to chase away that memory. It wasn't the time to think about that.
"Dear Xeno," Gen intoned, clearly furious, "I know that sometimes the impulse to get rid of the incompetent is strong... but you can't threaten to petrify them!"
Xeno, with his arms crossed, returned the gaze coldly. Stanley, leaning against the wall, watched in silence with that slight curve at the corner of his mouth that indicated he was enjoying every second of the spectacle.
Senku entered the laboratory, raising an eyebrow while Chrome followed closely behind him.
"Well, and here I thought today would be a quiet day before the test?"
Gen turned toward him for a moment, and Senku could see a flash of something in his eyes before he turned his attention back to Xeno.
"Oh, quiet it was going to be," Gen replied still tapping Xeno's chest, "until here our esteemed colleague decided that threats are a valid form of motivation."
"It works," Xeno intervened, with a firm voice.
"Yeah, sure," Gen replied with sarcasm, "just what we need before testing a time machine: half the team wanting to quit."
Senku snorted and headed toward the blackboard where he had the latest equations written down. He didn't pay too much attention to the argument; if Gen was already there, the problem wouldn't last long. The mentalist knew how to deactivate Xeno without even getting his hands dirty, and at that moment, he had more important things to think about.
He moved toward the central console, determined to focus on what really mattered. He made a brief and dry gesture to Chrome to turn on the controls, and the young man hurried to press the series of switches until the machine responded with a deep hum that resonated throughout the laboratory.
The sound cut the argument immediately. All heads turned toward them, and Senku felt a small but real satisfaction seeing that he had managed to capture everyone's attention without saying a word.
Behind him, he heard the creak of leather from Xeno's glove as he uncrossed his arms and approached.
"We'll still have to wait a few hours," he commented, apparently happy to have gotten rid of the mentalist. "The machine will take a moment to start... enough time for us to reconsider and send one of those incompetents instead of you."
Senku barely turned his head, just enough for his left eye to catch Xeno's gaze. He didn't respond immediately; his fingers continued sliding over the switches while the systems began their activation sequence.
"I'm afraid, doctor, that I've already made my decision."
The machine's hum intensified slightly, filling the tense silence that followed his words. Chrome shifted uncomfortably next to him, but said nothing.
"Ah, but if that decision involves skipping breakfast, I'm afraid you'll have to discuss it with me."
Gen's voice burst from behind them. Before Senku could turn around, the mentalist had already taken two agile steps, positioning himself at his side and, without asking permission, hooking an arm under his.
"What the hell...?" Senku started, but Gen was already dragging him toward the door.
"Chrome, dear, could you supervise that everything keeps working?" Gen said over his shoulder, maintaining that sweet tone he used when he wouldn't accept argument. "We'll be back in a few minutes."
Senku tried to resist, but Gen had a surprisingly firm grip for someone of his build.
"Gen, let me go. I have work to do."
"And I have a scientist to feed," the mentalist replied, without slowing his pace. "Priorities, dear."
"Mentalist, I don't have... wait," Senku raised an eyebrow, "how did you know I didn't have breakfast?"
Gen tilted his head, disinterested.
"A magician never reveals his secrets."
Senku let out a dry snort, but didn't resist anymore. His steps ended up synchronizing with the mentalist's as they left the laboratory, crossing the hallway illuminated by white light tubes that hummed weakly. The anxiety to return was a constant weight on his back, but he had to admit that Gen was right: with an empty stomach, he wouldn't last too long. And he had promised himself to eat something already in the laboratory.
The cafeteria was half empty, impregnated with the aroma of freshly ground coffee and the light murmur of vending machines. Gen guided him to a table by the window. They settled into the metal chairs; Gen, as always, without losing composure, crossed one leg over the other and raised a hand to call the waiter with an elegant gesture.
He ordered coffee for both and some light food, before leaning back slightly on one elbow, studying him with an expression that feigned nonchalance.
The silence stretched between them while they waited. Senku drummed his fingers on the table, looking toward the window where the complex's courtyard could be seen. Gen kept watching him with that calculating gaze he knew so well.
"Well," Senku finally said, "are you going to say something or are we going to stay here all morning pretending this is normal?"
Gen played with the edge of his shirt and looked directly into his eyes for the first time since they had sat down.
"You're still an idiot, you know?" he said with a calm but firm voice. "I'm still furious with you for thinking you're a hero. But..." he paused, sighing slightly. "I can't help worrying, even though it bothers me to admit it."
Senku felt something heavy settle in his chest at the raw honesty in the mentalist's voice.
"I know," he responded in a low voice, without looking away. "But I'm the one who must do this."
Gen nodded slowly, as if he had been expecting exactly that answer.
"Out of academic curiosity..." he began with a light voice, "what exactly are the risks of your trip?"
"Mentalist, we already discussed this yesterday."
Gen's expression didn't change, but Senku could notice the slight tremor in his fingers when he took the napkin. Maybe another wouldn't have noticed it, but he did. He knew the mentalist's micro-expressions too well not to realize it.
The waiter arrived with their coffees, interrupting the moment. Gen thanked him with a perfect smile while Senku observed how his hands had stabilized again.
"Yes, we discussed it," Gen finally said, stirring the sugar with deliberately slow movements. "But I didn't get clear answers."
Senku exhaled, knowing he wouldn't get out of this, and began to enumerate without taking his eyes off him.
"Temporal distortion, memory loss, cellular desynchronization... and, of course, the small possibility that my mass disperses into subatomic particles."
"Oh, charming," Gen said after a few seconds, with a smile that didn't reach his eyes. "And I suppose you have everything calculated to the millimeter, right?"
Senku took a sip of coffee, noticing that Gen had put exactly the amount of sugar he detested.
"Everything is safe within normal parameters."
"Normal parameters?" Gen left the spoon on the plate with a soft clink. "Senku, there's nothing normal about time travel."
Senku examined him carefully. The mentalist looked exhausted, with deeper dark circles than usual and a slight slouch in his shoulders that contradicted his always elegant pose. Although somehow he still looked impeccable in that purple shirt that fit him perfectly. It was irritating how Gen could look so put-together even when he had clearly slept little, while Senku needed considerable effort to look barely presentable on his best days.
"Would you do it?" he asked then, because he needed to know if Gen would be willing to do the same thing he was asking him not to do.
The mentalist blinked, as if they had pulled him from a distant thought.
"What?"
"If I asked you... Would you be the test subject for the machine?"
Gen didn't hesitate for a second.
"Of course."
Senku froze, with the fork suspended halfway to his mouth. That direct answer hit him like a punch to the stomach.
"Then, what's the difference?" he asked. "Why is it okay for you to risk yourself but not me?"
The mentalist remained silent for a few seconds, looking at his coffee as if it contained the answers of the universe.
"It's different," he finally murmured, without looking up.
"Different how?"
"It just is."
The evasive answer irritated him more than it should. How could he be so casual about it when it came to his own life, but so protective when it came to Senku's?
He left the fork on the tray with more force than necessary and stood up, to Gen's great displeasure. It was best to ignore this whole conversation before the mentalist managed to convince him to back down.
"You should stop worrying so much about me and focus on fixing your morning mess," he said, forcing a casual tone he didn't feel. "If I see your things scattered in my bathroom again, I'm going to throw them all away."
Gen sighed, clearly tired.
"I'll fix them soon," he responded without looking up. "It's not like I have many other things to think about right now."
Senku nodded curtly, closing the conversation.
Gen narrowed his eyes, immediately recognizing the evasion tactic, without trying to stop him when Senku walked away with determined steps.
He stayed there, watching the door through which he had disappeared.
The coffee slowly cooled between his hands.
A couple of hours later, Senku stood in the center of the enormous room. The machine, a monstrous structure of metal, cables and crystal, rose imposingly before him. Around him, the kingdom of science team moved in organized chaos, checking monitors, adjusting controls and shouting instructions at each other over the noise.
"Senku!" Chrome shouted from the top of a walkway, with a tablet in his hand. "Energy levels are at 95% and rising! The power source is responding as we expected."
Senku nodded, feeling how adrenaline began to run through his veins. After months of calculations, tests and adjustments, he was finally here. The moment he had been waiting for since he conceived the idea of the time machine.
At another end, Xeno analyzed a series of monitors, frowning while verifying each variable in search of possible errors.
"The equations remain stable," Xeno announced. "Temporal distortion is within expected parameters. The probability of cellular desynchronization is... acceptable."
"One minute left to reach 100%!" Chrome announced with excitement, although his enthusiasm mixed with nervousness. "This is really going to work!"
Ryusui burst into the laboratory at that moment with an entrance as exuberant as always. The doors swung wide open when the blonde pushed his way through the group of scientists, followed closely by Francois who carried a tea tray as if it were completely normal to interrupt a scientific experiment of this magnitude.
"You know you need a permit to be here, right?" Senku scolded him, his voice barely audible over the roar of the machine behind them.
"Did you really think I'd miss the first time travel in history?" Ryusui declared without the slightest trace of shame, adjusting his gloves with that characteristic smile of his. "Besides, remember that I'm the one funding this."
Senku raised an eyebrow but didn't protest. The argument was valid, although that didn't mean he had to admit it out loud.
"You arrived just in time for the most exciting part," he then responded pointing to the monitors showing the charging progress. "Only the final adjustments and safety checks remain. Get behind the bulletproof glass and observe the power of science."
Ryusui nodded with excitement heading toward the safe room, although when he saw that Gen was the only person there he let out a mocking laugh toward Senku.
"Didn't you say you need a permit to be here?" he commented with a provocative tone, clearly enjoying the contradiction.
Senku clicked his tongue with irritation.
"Shut up and go, you're delaying this," he muttered returning his attention to the controls, but couldn't avoid the smile that appeared at the corner of his mouth.
It was now or never.
He observed his greatest creation one last time. The time machine occupied almost the entire center of the laboratory with a main structure resembling that of a colossal petrifying medusa, it was formed by a metallic framework with long tubes and cables that descended like tentacles. Each one pulsed with bluish flashes, transmitting energy toward the central core, a spherical chamber large enough to contain a person. The deep hum of the generators was constant, accompanied by the rhythmic tapping of the cooling pumps.
Chrome approached with a protective suit folded in his arms, the silver material shining under the laboratory lights.
"It's time to put it on," he announced while unfolding the specialized garment. "Kaseki designed the isolation system following your exact specifications."
Senku extended his arms allowing Chrome to slide the suit's sleeves over him. The material was heavier than expected, with internal layers containing conductive fibers to dissipate any electrical overload. In case there was an energy failure with him inside.
"Where's Suika?" Senku asked while checking the wrist seals. "She was supposed to verify the biometric sensors."
"She's still not out of school," Chrome responded with a nervous smile. "She sent me a message a while ago saying she had a mishap but insisted we shouldn't wait for her. She said that anyway if the machine worked we'd end up testing it again and she wouldn't miss that."
Senku tilted his head with confusion. Suika was one of the most excited about this day, so it was strange that she wasn't present. Although he couldn't think about it much more when the suit's sensor began to emit a beep as it activated.
"The biometric sensors are working," Senku reported checking the small panel on his forearm. "Body temperature, heart rate and blood pressure are transmitted directly to the external monitors."
Chrome nodded upon receiving the data on his tablet and moved away giving him space. Senku breathed deeply, adjusted the suit's helmet one last time and once ready crossed the access ramp, holding onto the handrail to not lose balance when the vibration increased. The interior of the chamber was illuminated by an intense white light and, as he approached, he felt the heat generated by the energy transfer.
Before entering completely, he turned his head toward the safety room. Gen was next to the glass, watching him in silence. His posture was straight, but his tense shoulders and the rigidity in his jaw betrayed the worry he had been trying to hide all morning. When their gazes met, Senku noticed that his eyes, normally lively, now showed pure concern.
Without saying anything more, Senku took the last step and positioned himself in the center of the core. The hatch closed behind him with a dry thud and the hydraulic locks activated. The light intensified rapidly, forcing him to squint. The internal indicators began to change from green to a yellow blink, and the sound of the transformers became more acute.
"Time and date of the test: January twenty-seventh, twelve-ten in the morning!" Xeno shouted as the last instruction.
The air inside the core had become dense, charged with an energy that made every cell in his body tingle. The last thing he managed to see, before the luminosity completely covered his field of vision, were Gen's eyes, fixed on him through the glass.
And then everything faded away.
Senku woke up disoriented, his mouth felt dry as paper and he had an annoying stabbing pain hammering behind his temples. The metallic taste on his tongue vaguely reminded him of when he stayed awake too many hours in the laboratory.
Where the hell was he?
His eyes swept the place quickly, blinking several times to focus his blurry vision. The light filtered through the curtains hurt him, but an instant was enough to recognize the familiar details: the messy desk with formulas scribbled on loose papers, the scattered screwdrivers, his laptop still open. And that stupid broken fan that sounded louder than usual.
His room. He was in his room.
He sat up abruptly, ignoring the dizziness that hit him like a wave. How had he gotten here? The last thing he remembered was being in the machine's core, the blinding light, Gen looking at him with concern through the glass...
"What the fuck...?" he muttered, running a hand through his hair.
According to the programmed calculations, the trip shouldn't be long; being the first test, he should have returned barely a day after the date of the first jump. In that case, he would have to be in the laboratory, coming out of the machine... not in his bed, waking up as if it were a normal morning.
Something had gone wrong.
He sat up completely, ignoring the stiffness of his muscles and the constant buzzing of the broken fan in the corner. Getting up too quickly, dizziness forced him to close his eyes for an instant, but he dismissed it and approached his forgotten computer on the desk. He turned on the screen impatiently.
January 27th of the year 5757. Seven in the morning.
He stared at the date fixedly, as if the numbers were going to change if he looked at them long enough. January twenty-seventh. The same day as the test.
"No, no, no..." he muttered, refreshing the page several times.
The date didn't change. It remained the same.
That didn't make sense. It was impossible. The trip had been programmed for twenty-four hours forward, not backward. And not even that: Senku had gotten into the machine at twelve-ten in the morning. Which meant he had been sent barely five hours into the past.
But then, where was the Senku from this timeline? Had he been replaced? Erased from existence? The idea sent a chill down his spine. Temporal paradoxes were dangerous territory, and apparently he had fallen right into one.
He looked down at his clothes. He was wearing the same pajamas he had gone to bed with the night before: a worn gray t-shirt with the periodic table logo that had lost color after so many washes, and navy blue cotton pants with a small hole in the left knee. If he had really traveled to the past, why was he wearing exactly the same sleepwear? And why hadn't he appeared in the laboratory, where he was supposed to materialize?
What had gone wrong?
Actually, hundreds of things could have gone wrong.
He rubbed his temples, trying to think clearly. The calculations were perfect, he had reviewed each equation dozens of times. The machine had worked correctly during preliminary tests. The energy levels were stable when it was activated.
But something had failed, obviously.
At least he could settle for one thing: the machine was working. It was a disaster... but it worked.
With a shrug he headed to the bathroom with more careful steps this time, vaguely remembering something about the table, but he had barely advanced two meters when his little toe crashed against the table leg, and the pain went through him forcefully.
"Fuck!" he yelled, automatically jumping on one foot while grabbing the other. "Seriously? Again?"
The pain pulsed with the same disproportionate intensity, but this time frustration overcame physical shock. He had hit himself in exactly the same place, in the same way. How was it possible that he had repeated the same mistake when he clearly had the feeling that something like this could happen?
"Damn it," he muttered through his teeth, limping toward the bathroom while rubbing his sore foot. "What kind of idiot hits himself twice against the same table on the same day?"
Apparently, him.
Upon opening the bathroom door, he encountered the scene he was already expecting: Gen's jars scattered all over the sink as if it were his personal territory.
This time he didn't move the products aside but simply avoided them, especially avoiding touching the lotion bottle he knew was misplaced.
He opened the drawer and there it was: his toothbrush in the same deplorable state. The bristles completely splayed, the deep bite marks on the back. This time he didn't even bother looking at it, he simply threw it in the trash without any ceremony.
He brushed his teeth with a new one quickly, but the minty taste didn't manage to clear his mind as much as before. The déjà vu weighed on him like a dense fog.
Without bothering to shower with cold water this time, he headed directly to get dressed. He put on clean clothes with efficient speed and left Yuzuriha's lab coat on the chair without folding or picking it up, completely aware that he had already lived this decision before.
It was unsettling to repeat these movements knowing he had already done them. Each action felt like an echo of something previous, but he couldn't help performing them. Although he managed to speed up the process considerably: he must have at least twenty minutes of advantage.
So, just like he did a couple of hours ago, he didn't have breakfast. He closed his apartment door with a slight thud and went down the stairs to his car. The engine started with a soft and familiar purr, and he drove hurriedly through the streets that were still lightly traveled.
When he arrived he parked without difficulty in his assigned spot, ignoring the metallic shine of the automatic doors that opened by themselves as he passed. And when he reached the elevator, he noticed it was unoccupied, unlike the last time when he had to wait a few minutes.
The empty elevator confirmed what he already knew: he had arrived much earlier than the previous time. Senku smiled feeling proud of his temporal efficiency until he opened the laboratory door and—
Fuck.
The smile was erased from his face as if he had been slapped.
Xeno had Stanley pressed against the laboratory wall, their mouths connected in an intense kiss that had clearly been going on for several minutes. Stanley had one hand firmly planted on Xeno's nape while the other clung to his lab coat, and the scientist seemed completely surrendered to the other man's control.
And it seemed neither of them had noticed his presence because the kiss seemed to intensify with each passing second.
Senku blinked several times, as if that would change what he was seeing. This definitely wasn't the scene he remembered. Gen wasn't scolding Xeno, and he didn't seem to be here either. Instead, what was happening was... this.
He stood in the entrance, completely lost. Had he arrived too early? Or maybe things had changed because he had arrived earlier?
He cleared his throat loudly, feeling the color rise to his cheeks.
Both separated quickly. Xeno's face was completely flushed, and an expression of slight excitement was still reflected in his eyes. Senku immediately wished he could erase that image from his memory.
"Senku," Xeno cleared his throat, trying to compose himself. "I didn't expect you to arrive so early."
Stanley, on the other hand, smiled with pride and moved away to his usual corner, clearly without any kind of shame.
"Yeah, well..." Senku cleared his throat. "I had work to do."
"Ah, of course," Xeno adjusted his clothes, disheveled after the heated kissing session. "What are you doing here so early?"
"Well, you see..."
"Dr. Xeno!" Gen's voice resonated from the hallway, clearly frustrated. "Please tell me why you've been threatening the new scientists!"
Damn it. Senku looked at the time and realized that, despite having arrived early, events were aligning again. At any moment then, Chrome would arrive excited to begin the machine tests.
Gen entered the laboratory like a storm. His eyes swept the room and stopped briefly on Senku before focusing on Xeno.
"Dear Xeno," Gen began with that sweetly venomous tone, "I know that sometimes the impulse to get rid of the incompetent is strong..."
There it was. The same words, the same tone. It seemed as if the universe was following a pattern.
"Wait a moment, mentalist," Senku intervened, raising a hand to stop him and Gen looked at him with contained rage, obviously planning to take out his frustrations from yesterday's fight by scolding the scientist. "Scold him later. Xeno, we can't do the tests today."
"What? Did you finally come to your senses and decide to send someone else up?"
"It's not that," Senku crossed his arms. "The machine isn't ready, a serious error occurred that made me go back in time instead of forward."
Xeno raised an eyebrow with incredulity.
"What are you trying to say?" Gen asked, his previous irritation transforming into concern.
"We've already done the tests," Senku explained, trying not to sound as tired as he felt. "But an error occurred. Today I got into the machine, exactly at twelve-ten in the day. Everything seemed to go well, but I woke up and it was seven in the morning of the same day."
An uncomfortable silence filled the laboratory. Stanley exchanged a glance with Xeno that didn't go unnoticed.
"That's not possible," Xeno finally responded, shaking his head. "The calculations were programmed to advance twenty-four hours, not go back."
Stanley crossed his arms, clearly skeptical.
"Are you saying you already lived through this entire day?" he asked. "And what proof do you have of that?"
"I don't think I need proof..." Senku sighed and ran his hand through his hair nervously. He could imagine a billion ways the machine could go wrong but this wasn't one of them. "And I wouldn't have them either, as I already said, I didn't spend much time in this day, the tests were done at noon, I got into the damn machine and suddenly it was seven in the morning again."
"Wait, wait," Gen waved his hands, genuinely confused. "So are you trying to say that you're not Senku?"
Senku stopped, not knowing how to explain it.
"It's not that I'm not..." he stopped, searching for the right words. "Technically I'm not the same Senku who should be here at this moment. I'm the Senku who already lived part of this day."
"It shouldn't be possible," Xeno shook his head but looked interested. "But well... it's a time machine! We're still not sure what exactly is possible or not."
What Xeno was saying made sense, although Senku couldn't understand how the programming had failed. In theory, going to the future was easy: you accelerate enough or get close to a massive gravitational field and that's it, time slows down. But traveling to the past was much more complicated and required conditions they weren't even sure were possible.
That's why they had programmed the trip to go one day forward, not back, at least until they knew how to perform them safely.
Senku observed the metal beast in front of him. Shaped like a giant jellyfish, the amount of details in its design was striking, so he had to admit it was frustrating that it had failed.
Trial and error, he supposed. That's how science worked, after all.
Now he had to figure out what exactly had gone wrong. The calculations had been reviewed multiple times, the temporal programming seemed correct, and yet here he was, convinced he had already lived this day. He would wait for Chrome to arrive with the complete diagnostic reports, the good thing was that the boy should already be arriving.
And since Suika was busy with her classes after that "mishap" Chrome had mentioned, she wouldn't arrive until after noon. Her absence was still strange considering how excited she had been to witness the test, but he supposed that school matters had priority.
He would have to call a couple more scientists to start from scratch. There was also the option of waiting for Ryusui and asking him to bring more specialized measurement equipment, although the navigator would probably insist on supervising the entire process again.
He rubbed his temples, feeling the weight of starting everything from the beginning.
At least the machine had sent him back just a few hours. If the error had been greater... well, waking up in the Stone Age again wouldn't have been exactly ideal.
Senku got so lost in his musings about possible temporal ramifications that he didn't notice when the laboratory gradually filled with people. The other scientists had arrived one by one, checking equipment and discussing in low voices, while he remained motionless in front of the machine, mentally reviewing every variable that could have failed.
"Senku!" Chrome appeared out of nowhere and started shaking him with enthusiasm, abruptly pulling him from his thoughts. "Is it true?! Did you really time travel?!"
Senku blinked several times, reorienting himself.
"Yes, Chrome. Although not exactly as we expected."
"Incredible!" Chrome practically bounced in place. "I mean, it's terrible that it went wrong, but it worked! The machine can really manipulate time! How did it feel? Did you see any tunnel of light? Did you feel like you were disintegrating?"
"It was more like... falling asleep and waking up in the wrong place," Senku responded dryly.
"But now we know it's possible," Chrome continued with excitement. "We just need to adjust the calculations, reprogram the temporal direction..."
"Exactly. That's why we need to start from scratch with the programming."
"From scratch?" Chrome raised his eyebrows with concern. "Was the error that serious?"
"I have no other choice," Senku responded, shrugging. "If we want to prevent it from happening again, I have to review every line of code. It's the only way to identify where everything went wrong."
"Ah, but if that decision involves skipping breakfast, I'm afraid you'll have to discuss it with me."
Gen's voice burst from behind them. Senku turned around and felt that strange sensation of déjà vu again. Although now there was a big difference, as this Gen seemed like a completely different person. His relaxed expression contrasted enormously with the tension he had shown during the previous morning, and that playful smile had returned to his face as if it had never left.
Before Senku could say anything, the mentalist had already taken two agile steps, positioning himself at his side and, without asking permission, hooking an arm under his.
"Chrome, dear, could you supervise that everything keeps working?" Gen said while already dragging him. "We'll be back in a few minutes."
Senku didn't try to resist this time, although his mind registered every gesture as a perfect echo of what he had experienced before. Gen maintained the same unexpectedly strong grip.
"You know, before the trip you told me something very similar," he commented, watching how Gen tilted his head slightly with curiosity.
Gen's mouth opened and closed for a few seconds, as if processing the information, before the smile widened until it became one of those "I told you so" expressions that Senku knew so well.
"I told you, taking that trip was a mistake."
The words brought him other memories, sharper this time. The fight from the night before filtered into his mind: the same face that now smiled at him had looked at him with pure rage and frustration. A broken Gen, yelling at him that he was an idiot for risking his life.
And in the end Gen had been right. As always.
At that moment Senku decided to test something. If he had really returned to the past, then Gen should react exactly the same as the first time to any comment he made. It was the perfect opportunity to confirm if his memories were real or simply a product of his overstimulated imagination.
"You left your things in my bathroom again," he finally said, wanting to test his theory. "Next time I'll throw them in the trash."
Gen's face scrunched up in an exaggerated pout. Senku was surprised to see that the reaction was different; that meant he could provoke changes according to his actions. Since he hadn't made the trip in this timeline, Gen's anger had diminished considerably.
"I don't have anywhere else to put them, dear!" Gen gestured dramatically. "Your apartment is too small and your bathroom too, but it's the only free space I have available."
"And why don't you look for your own apartment?" the question escaped Senku before he could think it through better.
The mentalist's expression faded for a moment and Senku cursed himself for being an idiot again. But Gen recovered his smile almost immediately, although now it looked forced.
"Because you know perfectly well that my stay here isn't permanent," he said with that light voice he used when he wanted to pretend something didn't affect him.
Before Senku could say anything more, they arrived at the cafeteria and the actions began to repeat.
For Senku, repeating the same conversations and actions was a peculiar experience, as if he were following a script he already knew by heart. But there was something comforting about it too. This time he knew that Gen would convince him to have breakfast, he knew exactly where they would sit in the laboratory cafeteria: the table by the window that looked out to the interior garden. He knew that Gen would cross one leg over the other with that elegant gesture he had, and would raise a hand to ask the waiter for coffee for both and a complete breakfast.
The familiarity of the movements was almost hypnotic. Gen settled into his seat with the same grace as before, his fingers drummed on the table in the same rhythm while waiting for the waiter.
But now there was a change: this time the mentalist seemed genuinely happy. There was no trace of that tension that had been building between them during the last few weeks, no worried looks every time they mentioned the time machine. The Gen of this morning joked naturally, his smiles were real, and when he leaned over to steal a piece of his toast, Senku didn't feel that knot in his stomach he had been carrying without realizing it.
So he allowed himself to finish his breakfast, drank all the coffee that Gen, this time, hadn't over-sweetened. At the same time, the scientist found himself enjoying the conversation with the mentalist. Gen told silly anecdotes about things he had done during the last few weeks he had been living in Japan, and it was... relaxing.
They returned to the laboratory after half an hour, and Senku found himself contemplating the machine with a completely new perspective. At exactly twelve-ten, he would have gotten into that metal beast. Instead, he stayed standing at a safe distance, observing every detail with critical eyes, looking for signs of the failure he knew existed somewhere in its mechanical entrails.
"You seem thoughtful," Chrome observed, who had been walking around the machine like a child in a candy store. "Do you already know what went wrong?"
"I have some theories," Senku murmured, without taking his eyes off the complex network of cables and circuits. "But I need more data before making any adjustments."
At exactly one-thirty, Suika appeared practically running through the laboratory doors, with her backpack still hanging from one shoulder and her cheeks flushed from running. Her school uniform looked more disheveled than usual: the skirt had a small tear on one side and one of the sleeves of her white shirt was slightly stretched, plus she had a subtle stain on the lapel of her blazer that didn't seem to be from food.
Senku noticed the details of the disorder, but attributed them to the rush to get to the laboratory. Suika had always been somewhat careless with her appearance when she got excited about experiments.
"Senku! I'm here!" she panted looking really agitated. "Is it true that the machine works? Chrome told me you time traveled?"
And so began another cycle of explanations, although this time Senku found some entertainment in observing the genuine amazement reactions. Suika practically glowed with excitement, asking question after question with that insatiable curiosity that reminded him of himself at her age.
The following hours blurred into a familiar but slightly altered sequence of work. They reviewed every component and every line of code. Gen stayed longer than usual, apparently fascinated by the process, although Senku suspected he had actually stayed to make sure he ate something during the day.
When the sun began to set, tinting the laboratory windows a golden orange, Xeno finally looked up from his notes.
"All right, enough for today," he announced, stretching with an audible crack of bones. "Senku, you need to sleep something if you want your brain to function tomorrow. And don't come to me with that you can survive on three hours of sleep again."
Senku opened his mouth to protest, but Xeno cut him off with a look.
"It's not negotiable. Go home, shower, eat something that isn't coffee, and sleep like a normal human being. And also..." Xeno approached him to whisper in his ear. "I hope what you saw this morning stays between us, okay?"
Senku had actually hoped to be able to forget that mental image, but couldn't help joking.
"I just know that now I have something to blackmail you with."
Xeno looked at him with a stoic expression, but dismissed him with a dismissive wave of his hand.
"Leave before I have you killed again, and make sure not to arrive so early tomorrow."
Gen, who had been playing with his phone in a corner, got up with a smile.
"Perfect. I'll make sure he follows orders, Dr. Xeno," the mentalist dragged him along. "After all, someone has to take care that our mad scientist doesn't become even madder after time traveling."
Senku didn't have time to say goodbye and was dragged out of the building toward his own vehicle and forced to sit in the passenger seat. He had no complaints, as he hated driving, but still couldn't help but be consumed by curiosity when he saw the mentalist take the wheel naturally.
"How did you get here this morning?" he asked, watching how Gen adjusted the mirrors. "I mean, you don't have a car."
It was true. He had been so focused on thinking about the time machine that he hadn't thought about it before, but Gen had left very early that morning. With whom? And in what vehicle? The mentalist didn't have his own car, and taxis weren't a service they had available yet.
Gen, who was fixing his hair using the rearview mirror reflection, didn't look away while responding with a casual tone.
"Dear Tsukasa brought me."
Senku straightened in his seat, surprised.
"Tsukasa? Is he in Japan?"
Gen gave him a genuinely confused look through the mirror.
"Of course, he's my bodyguard. He travels where I travel, you yourself assigned him that mission."
Right. Senku rubbed his temples, feeling how memories of past decisions reorganized in his mind. After the modern world began to resurge, the need for a diplomat who was capable of maintaining world order (and getting Senku to continue with his experiments regardless of the morality behind them) had naturally fallen to Gen.
And although Senku internally hated the idea of letting go of the only person who was capable of keeping up with him in any of his ideas, he knew there was no other option. It's not like he had many diplomat options back then. Gen had the charisma, emotional intelligence and, most importantly, the ability to make people do what he wanted without even realizing it.
Assigning Tsukasa as his bodyguard had been logical. The ex-emperor had the physical skills and, after everything they had been through, unwavering loyalty toward their small group.
And Gen had perfectly fulfilled his obligation, traveling around the entire world, in the middle of negotiations with other countries and world leaders. And this was the first time in many years that he had spent so much time in Japan since Taiju and Yuzuriha's wedding.
But the feeling was almost practically the same: Gen was here on business. And although Senku had suggested he could stay at his house —he had almost insisted, in fact— Gen's presence was practically null. The only thing that changed in Senku's life in these last few weeks was his bathroom, which over time had filled more and more with Gen's products.
It was like living with a very vain ghost.
And Gen also spent a lot of time lately with Tsukasa. Too much time, if Senku was honest with himself.
If Senku asked where he had gone to arrive so late, Gen would talk about the new downtown bar that Tsukasa had shown him. If he questioned why the change in clothing style, Gen would tell about how Tsukasa had suggested the change. And now, if he wanted to know how the mentalist managed to leave the house so early, it turned out that Tsukasa also served as a personal chauffeur.
Senku rubbed his nape, irritated with himself for the direction his thoughts had taken.
Shit. These aren't jealousy, right?
"It seems they've become close," he commented, maintaining a tone he hoped sounded casual but came out slightly more tense than he intended.
"When you're forced to spend so much time with a single person, that ends up happening," Gen responded naturally, without taking his eyes off the mirror while applying some product.
That? Was "that" referring to a friendship or something more? Senku felt how his jaw tensed involuntarily. Gen had always been too ambiguous with his words, and Senku hated not getting clear answers. Especially when it came to something that, apparently, mattered to him more than he was willing to admit.
"You left very early today," he said instead, changing tactics. "I didn't see you this morning."
There was an almost imperceptible pause in Gen's movements before he responded, and Senku wondered if he had imagined it or if he had really touched a nerve.
"Tsukasa had some things to do and asked me to accompany him," Gen shrugged while starting the car, and something about the way his long, agile fingers moved around the steering wheel made Senku swallow. Great.
The mentalist turned on the radio's small screen and a catchy song began to play, filling the silence that had settled between them. The artistic world, apparently, was also advancing by leaps and bounds since the petrification. Senku glanced at the time on the screen: ten thirty-five. Time travel had quite complicated his temporal perception, although at least now he knew exactly what moment he was in.
"By the way, I went into your room to go to the bathroom this morning," Gen commented naturally. "You looked like a complete disaster."
Senku tilted his head, raising an eyebrow with curiosity.
"You know there's another bathroom in the living room, right?"
Gen shrugged with a light movement, but his calm appearance still gave Senku chills. It was surprising the way this man could hide his anger, because although he looked completely calm now —driving through the unpaved streets, occasionally changing the radio station while humming some melody— it was a surprising contrast to how he had looked the night before, when tears had run down his face while yelling at him that he was an idiot for risking his life.
The memory produced an uncomfortable pang in his chest. Gen had been completely broken, vulnerable in a way that Senku rarely had the privilege of witnessing, and now he was acting as if nothing had happened. As if that heartbreaking conversation had never occurred.
And Senku still had to apologize for how he had reacted too, although the problem was that he didn't know how to bring up the topic without it sounding forced, especially when Gen acted as if nothing had happened between them.
"I know," Gen shifted gears with a fluid movement, and Senku was momentarily distracted watching how his arms tensed under the fabric of his shirt. "But your bathroom has a mirror, the living room one doesn't."
Of course it was for vanity. Senku almost smiled at how predictable Gen could be in certain aspects, even when everything else about him remained an enigma.
The rest of the trip passed in a silence that felt comfortable on the surface but loaded with all the words neither of them seemed willing to say. The background music filled the space between them while Senku took the opportunity to look out the window, observing how the city blurred into blurry lights and half-reconstructed buildings that rose like constant reminders of the world they had lost and were trying to recover.
Almost at eleven at night they arrived at the apartment, and Senku opened the door with his key before stepping aside to let Gen pass, who looked visibly exhausted. The dark circles under his eyes were more pronounced than usual and his shoulders fell slightly, he barely muttered a goodbye while passing by him, although not without first scolding him with a tired voice about needing to go to sleep immediately if he wanted to function the next day.
Senku nodded automatically, knowing perfectly well that he wouldn't heed that sensible advice, but when he saw the mentalist's slender figure walking away down the hallway toward the guest room, slightly dragging his feet on the wooden floor, something awakened in his chest. Maybe it was the guilt accumulated from the previous night's fight, maybe the urgent need to clear things up between them, or simply the irrational impulse not to let him go like that, carrying that unresolved tension.
"Hey! Mentalist!" he shouted, and his voice resonated louder than he had intended in the heavy silence of the apartment.
Gen stopped abruptly and turned slowly, with an expression of genuine surprise painted on his tired face.
"Yes, dear?"
"Tomorrow... tomorrow come with me to the laboratory," the words came out more rushed than he had planned. "Don't you dare leave before I do, understood?"
Gen's face remained confused for a few seconds and Senku wanted to mentally hit himself for being too abrupt with his request, although Gen smiled right away with that small and genuine expression that appeared when he was really pleased about something.
"It's okay, dear, but I don't think I can get up so early again," he responded with a hint of amusement in his tired voice.
Senku laughed, feeling how the tension in his shoulders eased for the first time in hours while something warm settled in his chest.
"And believe me, I don't want to arrive early again either."
With the mutual promise that they would sleep early, Senku entered his own room while the oppressive heat of the night forced him to turn on the broken fan. He observed it with resignation, noticing how it wobbled precariously with each movement while producing that irregular buzzing he had been ignoring for weeks.
It didn't worry him too much.
He would fix it tomorrow.