Chapter Text
Senku spun around in the chair Kaseki had made before this building was constructed. The reed cushions and bamboo frame held up well against the barrage of different positions he tested on it each day.
There were forty-five minutes before the faculty meeting. He should be doing something with them.
The bigger and more productive their research operations got, the more empty space Senku identified between anything that mattered. There never was a picosecond he could waste when he first woke up, not between knapping stone and beating rushes to try and get some workable material. Now with most of the old world tech already replicated, the only reason to crank out fundamental designs was for fun.
That's why he sat and spin around in this chair as the Newton's cradle clacked away and jars of river mud settled on the counter. Improved gold extraction wasn't going to hurry up just for him. He may as well try to observe noon. The skylight let in one beam that cut down to the packed dirt floor.
This strictly-no-smoking lab was a holdover from the early days after the depetrification, and Senku still liked it better here than in the fancy concrete buildings where they did the real work. The mud-and-reed walls housed whatever inert chemistry needed a cool place out of the sun. A circular lab bench with storage beneath ran along the walls, while the reject instruments from dozens of glassblowers served in qualitative or low-precision experiments. One of the new recruits—not that new, it was more than a year—had had the bright idea to make basic-principles posters and stick them up all over the place. The peeling crystalline structure chart tacked on to the support beams looked uncanny as Senku stared. Low light, junk equipment, dust everywhere, hah. It was a replica of a university basement to the nearest millimetre.
Senku spun a stylus over and under the thumb of his right hand. Who was he kidding. Attributing the Science Team's stagnation to the march of technology was a matter of systematic error. He still did pursue new discoveries for the joy of it. The time machine's failure had ground the rest of the Science Team's momentum to nothing.
The force that drove a lot of the researchers wasn't just breaking the boundaries of physics, it was getting back to a world where HVAC didn't come second to subsistence farming. Hah. He didn't want to reason out the reasons for scrapping it. Ishigami Village and the Petrification Kingdom were a magnitude of x10^2 people stacked against a magnitude of x 10^7, counting statues eroded, damaged, sunk, or otherwise irretrievably damaged. Senku had learned that a lot more of his team would make that trade than he felt comfortable with.
Scuttling sideways like a carciniform, Senku moved the wheeled chair down the bench to find a binder with clean paper in it. 5 out of the assembled 97 would do. The rest would be teaching materials, material safety data sheets, or records of experiments that went nowhere that never got filed in storage.
Kokahu had said he should just disable the machine. She had a point. Actually, he'd been in the process of sneaking into the assembly hangar with a wrench when Saionji stopped him. He was pretty convinced that any harm to the machine would cause more unrest than it was worth. It stayed complete for now. With a three-key system. The locations of two out of three were unknown variables.
Even with that assurance, most projects would stay in limbo until Senku could convince his team to destroy the greatest piece of engineering ever created by mankind. There were ongoing experiments with basic film cameras and notepads to test how different types of observation could override each other between time places, but those were just for the sake of science! They were also overseen by him personally. With Saionji and Kohaku present.
Leafing through some sheets of base-quality reed paper, Senku slid further down the lacquered wood bench towards the inkpots. He'd mark the changing angles down by the time of the wall clock in its cage. Not the best precision. It would be enough for some mental exercise.
The volatile situation, as Gen would put it, left Senku trying to figure out where to focus humanity's brightest minds that wouldn't ten billion percent end in disaster. He'd been going so stir-crazy that he had to go join Yuzuriha in the workshop just to keep himself from tearing his nails off. Hell, he'd even be out there with Taiju if he could work that long without fainting! Curse his low blood pressure. He just had to find some way—
A knock hit the door mid-crawl. Great. Some other functionary who thought he could charm the Stone World's greatest intellect into the private field.
Senku pushed himself back the way he came, and with one bony hand he stopped the Newton's cradle mid-swing.
They never learned! A pair of broad shoulders and a tight collared shirt only made Senku calculate the tensile strain on the buttons. Seriously, if he could have been swayed by simple physicality he'd have fallen for Taiju years ago. The oaf was a living, breathing marvel of a body. That didn't stop petty, short-sighted humans from trying to get him to support their social climbing.
"It's unlocked," he called.
If it was one of his team, they knew what to expect from him. If it wasn't, well, he wasn't interested in talking. He was too valuable to kill. Besides, security here was pretty good. It had to be.
Senku grabbed yesterday's sketch of a magnetic fusion containment shield and scribbled some version information on while the visitor slipped in quietly, to make it look like he was working. Just because he wasn't doing anything didn't mean he could waste time gabbing.
Huh.
The door didn't creak the way that it should. Whoever opened it had to be supporting its weight to minimize friction on the hinges.
Apart from that, he didn't hear the nervous appeals he should have. Was his visitor tongue-tied in front of the stone world's saviour? Hah.
"What?" he snapped. "Make it quick, I don't have all day."
"You're an orrendous-hay host, dear Senku."
00:00:00
The counter reset.
As his fingers froze around the stylus, Senku estimated that a man of Ryusui or Chrome's strength would have deformed the wooden fibres and shattered the structure.
His mind kept going while his body completed the process of locking up. Damaging the stylus would result in more debris piling up on the bench. To reduce the fire and splinter hazard, he would be responsible for tidying up. These tasks would need to be performed after his heart had restarted the flow of blood to his limbs. The tendons in his wrists would have to soften again to let him grip the dustpan in the corner. Last, his knees would have to unbend to stand him up from this chair, then bend again to propel him to the bin. Breaking the pen would be incredibly inefficient in his current state.
Good thing he was weak.
"Mentalist," he managed.
The pseudo-petrification he was undergoing did not extend to his throat. Small mercies. He doubted he had the physical capacity to stand and face Gen.
"Still haven't learned my name, have you?"
There might have been a dry ice canister in here, the way Senku's chest constricted.
"Gen."
"Ding ding ding! And the prize goes to...Doctor Ishigami."
He moved like a sleepwalker. One appendage after another pulled muscles and contracted others. At the end of the long process, Senku was facing the door.
Looking at Asagiri Gen. The stage magician. Only the tips of his fingers reached past the end of one extended sleeve, held out beside him to close the door. The other hand was hidden. Had he changed his haori from the first one Yuzuriha gave him? Senku wouldn't know, he never paid attention. His immediate breathing difficulty was occupying most of his processing power.
Wait.
Gen was silent, Senku realized, not saying anything. He also wasn't stationary. Instead of meeting Senku, Gen shut the door and wandered over to a different part of the room. The apparatus set up for titration training. Gen's long neck craned over it like a desk lamp. Leave it to him to use his tricks. He was going to force Senku to make the first move? Hah. Fine by him.
He had information to share with Gen.
"You're here," he said.
Stupid. What a stupid start to this conversation. Was Senku two years old and struggling with object permanence? Was he a quantum theorist, trying to establish the position of a waveform electron? Of course Gen was here. Why shouldn't he just throw up a spark in this room full of dry, particulate matter and eliminate the problem while he could.
"I am."
Senku stared at him. That was the best he could do for eye contact if Gen didn't want to look back.
"Good."
He took two metre long steps. Gen had moved on to the Materials Squad's segment of the bench. He could smell the alcohol solvent coming off. If he didn't know how long it took for it to dampen his nervous system, he would have thought it was affecting him.
"How are things, dear Senku?" he asked him.
"We built the time machine. We cracked the fourth dimension."
"Is that so?" said Gen.
He didn't move from where he was inspecting the drying resin composites in their clamps. Why wasn't he reacting? Senku remembered the look on his face down to nano scale from when he'd announced the damn project.
"I should be urpised-say," he went on, "But dear Senku just keeps making wonders."
Finally, he turned to look at Senku. It felt like there wasn't a millimetre of distance between them across the room. This was the necessary background he had to communicate even while the mass density of guilt hanging over him was building.
"We can't use it to stop the petrification, or end it early," said Senku, the prepared speech flashing across his mind. "The paradox—"
"And how are you, dear Senku?" Gen cut in. The voice was pitched to carry across an auditorium. It ten billion percent overpowered Senku. Like a chime it cleared the room and echoed.
In the falling dust, Senku closed his moth. He opened it again. He let his shoulder relax. He shouldn't feel this nervous talking to Gen. It was Gen!
"…bored."
Maybe the mentalist was confused. There wasn't a millimetre-long line on his face that Senku didn't have memorized, and none of them were creased in shock or worry. It was like he was seeing the factory model before configuration or formatting. Had he said something wrong?
Then Gen started to laugh.
"What?"
The carbon dioxide contamination Senku had imagined was rapidly converting to nitrous oxide, a euphoric analgesic that made it hard not to laugh with him.
"I'm—" Gen tried to catch his breath. "—I'm orry-say, it's just, that's—you should lie!"
Same old mentalist. For a guy who could make people dance to his tune, he was horrible at setting the mood.
"Why? You'd know if I was," Senku grumbled.
"It's polite," insisted Gen. "Though you wouldn't know anything about that, would you, dear Senku?"
"Are you still mad about what I said to the Why-Man?" he guessed.
"What on earth are you talking about?"
Senku tried to find his balance, closing the distance between them. There had to be some reason Gen broke his exile to come here. There wasn't a picosecond's chance that he just wanted to see Senku, or else he'd have come back earlier. Gen's love for creature comforts never outweighed his sense of duty. Why wasn't he saying anything? He was just going for small talk. He had to be trying to weasel it out of him like he did with everyone else. Senku tried not to feel hurt.
Gen was good at his job, so he ten billion percent should have known that he would do what Gen asked.
"It worked out for us anyway, so I didn't see why you were upset," he said.
"That's entirely eside-bay the point, dear Senku." Gen looked like he was in on some joke Senku wasn't getting. "Oh, well. So you're bored."
"Yeah. Now can I get on what what I was saying? Or do I have to act polite to you until you're satisfied, huh?"
Through the confusion, Senku could admit that he'd missed sparring with Gen.
"I wouldn't mind that," Gen said mildly. "Do go on, though. I'm sure what happened with your paradox was ery-vay important."
That he'd missed Gen.
"It was."
Senku tapped his fingers against the bench top instinctively, looking away. He needed to think. It was always easy to do with Gen around.
"You know we built the time machine."
Now, where had the mentalist heard about it? Was Gen living in Japan this whole time? Senku was ten billion percent certain he'd left again after Yuzuriha and Taiju's wedding. They said goodbye. Senku didn't always pay attention to everyday affairs when he was wrapped up in a project, but he did have a good memory. That wasn't something he'd miss. If Gen could come here often, to the lab, he would. Hah. Senku'd drag him if he had to.
"We did some tests with it. We can send back transmissions, but the paradox that depetrification would with the Stone World might erase the existence of the machine, and leave us ten billion percent screwed," he said.
A faint noise told him that Gen had settled against the bench. "Screwed how? Would the world just—?" There was a rustling like Gen was moving his hands. He did that when he was figuring something out, which was why he had them covered so often. Time travel was something most humans couldn't even conceptualize. Gen was still trying.
Senku bit down the warm feeling rising like bile.
"No. We can't know what's going to happen. The most probable outcome is that stopping the petrification erases the future. Negotiating with Why-Man is the only permanent solution. If that doesn't happen in the past, then we could create a loop where the petrification is delayed by a few months, and an alternate present results in the development of another time machine," he explained.
"Erasing the future," said Gen. "That means…"
"Yeah. The Science Team will decide how to get rid of it. If they don't—" he hesitated.
No, there wasn't any time for that. He was still going to give Gen his story. It was his responsibility to tell the man he lied to how he was going to crush his hopes. No matter what Gen thought of him.
"If they don't," he forced out, "I'm going to remove the resonance chamber."
"That sounds…omplex-cay."
Senku's head whipped around. He ten billion percent kept this project under locks, but the mentalist still looked…
Just like Gen. He had his listening face on. His face didn't twitch a millimetre.
He'd always known what Senku was going to say. How?
They had drafted the plan, he and Xeno, before starting work on the time machine. Gen must have guessed that. Scientists learned the lesson the hard way that accidents happened. Even if they avoided the paradox problem, they couldn't rule out someone using the time machine to erase people from existence unnoticed. Smashing statues. Erasing people. Undoing births. Tsukasa, Saionji, and a few others had instructions to implement the disabling procedure if there was any unauthorized or inconsistent access.
"That's what it uses to breach time streams," he explained. "It needs micro-scale precision. I'll give it to Kaseki to melt down. We're going to install a magnetic field generation circuit around the facility to make sure there's ten billion percent too much interference to tune a new one.
"I'm sorry, Gen."
Senku forced himself to keep looking him in the eye, second after second while the subject under observation gave him nothing to go on. He didn't do social codes. It took his own unmatched self-control not to start shaking the mentalist by the shoulders and asking him if he was upset.
"I lied when I said I could stop the petrification. I won't lie to you again."
"Is that the truth?" asked Gen.
The stakes had been higher. The uncertainty had never been. There was no contingency if Gen didn't forgive him. There was no substitute for the best talker he'd ever met. New hands were always there for work, new minds to calculate…
If Gen lost trust in him, then Senku would no longer be Senku. The left hand of his that guided the world would be cut off, requiring immediate cauterization and antibiotics to prevent sepsis from setting in.
"Yeah," he swore.
Gen watched him back as smooth and featureless as a telescope lens.
Then he laughed! Again?!
"Ahahah Senku, dear, didn't you ever do those riddles when you were a kid? If you were lying once, that means nothing! Look at me," he said. "How many people do you think I've said that to? 'I won't lie to you again' oh, that is imply-say ute-cay, my darling Senku. Geez."
Couldn't he see Senku was trying to be serious? He knew how much he hated lying. And he remembered what Gen said about the time machine when he saw their prototype, right before they got the graviton generator working! Ten billion percent, Senku hadn't imagined him crying while he made that speech. The most important scientific advance in history!
So why was Gen still giggling? His hand went to his ear automatically. Senku wasn't about to let this stump him.
"Something's either true or not true," he grumbled. "The astronauts on the Challenger aren't less dead because the engineers were overconfident instead of greedy. I told you that you'd get to go back to the old world. There isn't a millimetre's chance that will happen. So I'm sorry."
"Apology accepted, dear Senku."
Gen grinned, and Senku had to smile back. The giddy oxidated feeling wasn't going away while the mentalist was still here.
"Good. Now tell me what's so funny. You knew that we'd built the machine already," he said.
"Actually," Gen said slyly, "Dear Chrome asked me to talk you out of using time travel."
Huh?
"Chrome?" Senku's mind raced. "But he knew I was going to—why would he—?"
"Oh, I'm sure dear Chrome didn't think you would! He just thought, it might be ard-hay for you," said Gen soothingly. "It was sweet."
The usual silly grin spread across Gen's face as he waved his hands this way and that. They avoided knocking over the piles of glassware mounded up here and there in the lab bench and no matter how close they got, they missed his face. Sometimes by a millimetre. There was zero chance that Senku wouldn't notice how precise he was and feel a glow of admiration for it.
"Yeah. It'll be nice to get someone else to tell the physicists what I'm doing to their favourite toy," Senku recovered. That's right, Chrome hadn't been there for most of the discussions. He'd left just as soon as the first tests were showing promise.
Wait. He ten billion percent had volunteered to supervise that shipment.
Casting new eyes around the dim room, Senku wondered how long his most reliable assistant had been going behind his back. Hah. Chrome always had the spark of genius in him. He absorbed whatever Senku and Kaseki taught him like it was second nature, so why wouldn't he learn what Gen was always teaching them?
He grabbed the miraculously intact stylus off the table and wrote a note to thank Chrome and tell him not to interfere with his personal life another millimetre. In his own shorthand. What he'd said to him the night he proposed to Ruri was in confidence. And also what Senku had told him when Chrome asked about half a dozen questions over the years since Gen moved in with them.
"It's not that."
Senku suppressed a brief panic, knuckles white on the pen. "Oh. What? Did Chrome notice something else?" he said flatly. He was ten billion percent certain that there wasn't a tremor in his vocal cords. "About the machine. He needs to tell me."
"Not that either," said Gen casually. "You really aren't entimental-say, are you, Senku dearest?"
Glancing sideways, he saw the mentalist was distracted by the posters now. While he stared his fingers flicked invisible cards between them, fidgeting elegantly with sleeves rolled up. He was distracted and vulnerable. He hadn't noticed a millimetre's difference in Senku's composure.
"Of course not!"
He laughed in relief, but Gen only blinked at him.
"Demolishing the time machine…Senku." He used his name. That felt funny. "That's far more serious for you than it is for little old me."
"What are you saying?"
"You'd lose your link with dear Byakuya," Gen said quietly.
Dust motes drifted through the wide room as time stopped without any mass-energy interference.
Blink.
The angle of the sun was simple to find with one skylight.
Lose.
Senku had already marked out a mental sundial.
Link.
It was early summer. Long days. The sun was close to its furthest northward point in the sky, in this hemisphere.
Dear Byakuya.
Accounting for the door facing one point east by two points south, the light barely missed the mark he'd made at the precise centre.
Byakuya.
Eleven o'clock. Eratosthenes had measured the circumference of the earth from the angle of the sun at two separate points.
Dear.
One point alone was useless.
"Yeah," said Senku.
Gen hopped up on the countertop, toes brushing the ground as his long legs dangled.
"I don't know if I could make that call," he said. "You're strong."
"Of course you could," Senku scoffed.
He busied himself with cleaning part of the lab bench. There was no immediate need to have some of his notes out on the surface. There was an immediate need for a distraction.
"Ah, true. But if there was someone I loved so ery-vay much," said Gen, "Choosing not to go to them would be hard."
"Byakuya's already long gone." Senku knew his voice was too husky. "He said what he wanted. I'm ten billion percent sure he knows anything I could've told him."
"It's not something you practice for, grief. The second time can be worse."
"Yeah, and I've been dealing with it."
"I know."
Senku tried to remember if anyone had told him the mentalist was coming. There wasn't any evidence that anyone else had observed Gen in the lab, that he wasn't the product of extreme stress and grief causing hallucinations of someone he trusted implicitly, but Senku couldn't deny his own evidence as he added it up. Gen had the same duality as light, he made it possible to see things that weren't in Senku's visible spectrum, but Senku could never actually see him.
His head was aching trying not to look at Gen. The moment he did, he'd lose all grip on where this was going.
"Did Chrome think I'd give him up, then?" he said. "Trade my own labour force just to have my—have Byakuya back?"
"Ertainly-cay not! After everything you did to get here…I guess he just thought I should be helpful," Gen said. "It's my role."
Senku's notes were shoved into their binder. He had started counting the decimetre-scale density of warp and weft reeds in the composite building material through the welling tears. Was Gen reading the posters again? Senku just hoped he couldn't see his face.
"Besides," Gen added sadly. "I wanted to come home."
"Home. Hah."
Home? Their home?
There wasn't anything the mentalist said that he didn't think about before. It was one of his tricks. Either you had to trust everything he did, or you trusted nothing. There wasn't a millimetre's difference between his casual comments and his calculations. Right now the spotlight was far-off at the centre of the building and Gen was next to him. That had to mean something.
"Even the great mentalist gets homesick sometimes, dear Senku."
Gen had come to him, and he said that. What the hell was Senku supposed to think? How was he supposed to take that? The damned mentalist had found one point defect in him and applied pressure until he came apart.
Pushing away from the counter, Senku faced him. He opened his palms at his side and stood straight. That would send his body into a high-stress state by activating the sympathetic nervous system.
"It's not that." He forced himself to laugh. "You want to share a hut with me again?"
"Japan is my home," Gen countered, arms sheathing into their sleeves. "But if you really missed me, darling Senku…"
"Don't be gross," Senku said triumphantly. "I need to convince the old worlders on the Science Team to destroy our time travel capabilities. I'm not that good at talking."
"How uel-cray! You send me away for months, then you only take me back when I'm useful?"
Gen gave him an exaggerated swoon, but he sounded...hurt. Senku had hurt him. There wasn't a millimetre's chance he could take it back. Time travel was ethically and logistically infeasible.
"For seven hundred and eighty-three days," he said.
He cocked his head at Gen, challenging him to take another shot. It didn't happen.
Instead, the mentalist left him dangling like a magnet in a solenoid coil.
"You were away for seven hundred and eighty-three days, minus sixty-five days total spent in Japan between the depetrification and the current date."
Senku's heart drummed against his sternum.
Was it too late?
"Gen—"
"Yes, dear Senku?"
Senku kept an eye on Gen's smile, the kind he'd seen stay on in every possible sort of peril if he wanted to. There was no guarantee of anything with the mentalist apart from his kindness. For all he knew, Senku was walking right into a trap. He just couldn't make it out! It was impossible to observe the message Gen was conveying and know the position he was sending it from at the same time.
"Are you leaving Japan again?"
"After the time machine negotiations?"
"Yeah," he breathed.
Moving like a sea snake, Gen slid into the space behind Senku head-first. It forced him to twist his neck to the limit to keep watching him in the low light, then shuffle his body around like a kid watching planes overhead. Now he was just making him dance, the damn magician. It was a good thing Senku was a lot more agile here than in the old world.
"You told me to leave in the first place, Senku dear."
"It was the most rational choice that I had," he said. "Tell me. Please."
"I could be lying to you."
Senku searched Gen for any of the signs that he was ten billion percent certain he wouldn't find. He would be more productive looking for atoms using a magnifying glass.
"You won't."
"I don't know," Gen sighed.
And Senku's body shuddered. Flesh and organs maintained low brittleness even when completely frozen, he knew, which is why he didn't consider that moment to be heartbreak. It was heartcrunch at best. He put a hand out to steady himself.
"It's going to be an ong-lay time until this new world settles down," Gen continued.
"You," Senku stopped. "Where are you staying? You didn't arrive before today, not unless someone's hiding you."
Bowing his head, Gen smiled suspiciously at Senku.
"Little old me? I'm rooming with dear Kaseki and Suika. I only have to pay rent there in manual labour, you know," he said.
"I've got more work for you," Senku offered. "You could take Chrome's room."
"I wouldn't want to mess with his things. You know as well as I do, dear Senku, how particular dear Chrome is about his collection," Gen said airily.
"Nah, he's moved in with Ruri already."
They were following predetermined paths of orbit around one another, back under the known rules of the universe. Senku prepared to break them a second time.
"They're moving erribly-tay ickly-quay, don't you think? Cohabitating after what, sixteen years?"
The fine ends of Gen's bangs hung too close to Senku's face. Every breath he took few the stray strands close through suction, partially, Van der Waals' forces, and electrostatic attraction.
"Hah." The choppy hairs swayed. "Science has to come first. We'd be missing discoveries if everyone just mooned over other humans."
"All of dear Chrome's exploration and collecting, that definitely had nothing to do with dear Ruri," said Gen.
"You know I didn't say that, mentalist," Senku argued.
"So efensive-day!"
Gen stepped back without a microsecond's warning. It opened a vacuum between their two bodies. Barring any counteracting force, gravity drew two masses in empty space together.
Gravity would take too long. Senku stepped across the gap. If Gen wanted to make this difficult, then he'd make his way to him one millimetre at a time. Xeno's paradox could suck it.
"Will you stay with me, or not? I can take 'no' for an answer," he said fervently. "I just need the data."
They were face to face again. Again Gen stepped back. What was he doing? Why did he come here from so far away and then back off now? The gravitational forces pulling them together stopped at some point, balanced by electromagnetic repulsion.
Gen's head tilted curiously. The mentalist shouldn't look so sad. Strike that. He should look exactly as sad as he felt, because Senku prided himself on being his equal. He didn't have to treat him like another patient. Senku hoped. He hoped like he'd practised, over three thousand and seven hundred years, waiting for the day he could stop counting. Gen shouldn't look so sad because Senku couldn't stand looking at the annoying way his eyebrows scrunched.
"Please, dear Senku. I'm more than willing to take a spare room if you don't make me pay for it. That's not what you're asking," said Gen.
"Isn't it?"
"Tell me in your own words:" Gen's eyes drew him in like black holes. "What do you want from little old me?"
His own words.
Him.
What did he want?
Hah!
Energy flooded Senku from his fight-or-flight reserves. Didn't he know? Senku never said anything he wasn't ten billion percent sure of. There wasn't a millimetre's chance Gen would catch him in a lie. Talking in circles like this wasn't the same as avoiding the truth. He was only ever giving Gen a way to weasel out.
Senku grinned. "I want you."
The look on Gen's face was something he'd savour for the rest of his life.
"Keeping the world peace is still the most important thing. I need you as a diplomat more than I need you as a sounding board. It's not the best use of your skills. So, we'll have to decide that together," said Senku. "But I want you around. With me. Indefinitely."
Gen's eyebrows had climbed halfway up his skull. His eyes were wide and his pupils dilated like a cat's. Senku took advantage of the silence to make his argument.
"I won't stop my research if I think I can come up with something that will help humanity or advance knowledge. I won't abandon my work to keep you company. I won't stop talking about it if you don't want to hear it. If you get sick, then I'll leave you in bed to go make a cure."
"Senku, what are you—"
"I'm confessing my feelings," he said. "Keep up, mentalist. Now, Taiju can keep you company in an emergency. If you break your leg, I'll make you crutches. The doctors are the ones who'll stay by your bedside. If you go missing at sea, then Saionji and the radar team can look for you. I'll be working. I'll check our charts for the ocean currents where you went down."
"Okay. Okay, fine. What else?"
"I will promise that I'll listen to you," Senku swore. "I'll explain what I'm talking about until you understand it. If you tell me something that I don't get, then I'll take notes and come back with questions. I'll take work home instead of staying at the lab. I won't let you come home to an empty house. Not by a millimetre."
Senku barrelled on before the manic high ran out.
"And, if you ask me to do anything, I will do it. The only thing I won't do is hurt people, or let them get hurt. I never lie," he explained. "I never leave my margin of error. I want your brain to be the other half of mine because you know things that I'll never understand. I want to talk to you at regular intervals because I miss you when you're gone. The most important thing is: I want you to know the exact significance you have to me and its order of magnitude. Those are the controlled conditions I can set for you."
Gen looked obviously shaken. That meant that he wanted Senku to see that he was. Senku was ten billion percent certain that the mentalist was being sentimental. It was a habit he'd never given up.
"Tell me if you can accept those parameters," he finished breathlessly.
"Senku—dear Senku."
That was the second time today that Gen used his exact name. He was stationary, unmoving for once in the ever-expanding universe.
"That's an ary-scay amount of power."
"I didn't lie."
"What if I ask you to do something you don't want to? What if I say, Senku, dearest, I need you to go get healing crystals for me? What if I make you convert to spiritualism?" Gen laughed. "Eally-ray, that's a stupid thing to say!"
A shockwave of relief knocked the tension out of Senku's face. He couldn't stop himself from grinning.
"Oh yeah?" Senku advanced on Gen again, one step at a time. "Mentalist, you have a good memory. Tell me—"
He planted a foot on the pockmarked floor, right between Gen's legs, and stepped into his space. Even when Senku had the advantage of surprise, Gen still leapt back before they ever so much as brushed against each other. Senku never drew close enough to do more than feel Gen's breath. It blew hot on his cheek.
"—when have you ever touched me?"
"Are you azy-cray?!"
Satisfied, Senku straightened up.
"It's not hard. You know I don't like being touched. You know I'm unable to resist it," he declared. "Not with a high success rate. You still try not to touch me. That means that when you know I have a boundary, mentalist, I can trust you to never, ever move past it. Am I wrong?"
"You've got me," Gen said ruefully.
"Yeah. So, what's your answer?"
The different moving components that made up Asagiri Gen shifted like the hemispheres from winter to summer. Senku looked on with the same wonder he felt for those stars.
"Senku. Dear, dear, Senku. When have I ever refused you?"
"I know what you mean, but I need you to tell me what you want. Exactly," he said. "Without bias or error. Do you want to be with me?"
"Yes!. As eird-way as it sounds, I like you. I really like you. So, because I want to, I think I'm going to move into Chrome's old room, and because I like talking to you, I'm going to stay there until you leave me. Is that acceptable to Doctor Ishigami?"
"Whether I gain or lose from it," Senku recalled, "Yeah. I can work with that."
A childish smile crawled from one side of Gen's face to the other, and once it was done Senku felt his face doing the same thing.
"Good," said Gen.
Senku raised a hand, pushing it over the line between them. Gen didn't flinch back as he raised it to his cheek, running a thumb along the line where his scar used to be.
"To be ten billion percent exact," he said. "I love you."
"Gross!"
Flicking his now-lab partner on the cheek, Senku grabbed Gen by the hand.
"Oh shut up. Come on, I need to mark the angle of the sun at noon. You're going to make me late."
"I would never do that, dear Senku. You are in perfect control of your own schedule," Gen teased. "Or, don't tell me you're getting sentimental?"
"Not even a millimetre," he said.
