Archive of Our Own ^beta

Chapter Text

It took just the slightest touch, his knuckles grazing the other's as he came to stand beside him. Just one touch, and he knew.  

Knew that this was the boy he had been mentoring over the internet for years — now a young man. Felt his awe at the piece of elegant machinery that stood before them. Sensed his desire for... funding?

Well. It's a good thing he happened to have his wallet with him.

Senku knew just as suddenly, the thought appearing in his mind as organically as one of his own, that this was the man who had been his mentor all this time — even though this was the first time they had ever met in person. He sensed his pride in him, the feeling making a small smile pull at Senku's lips.

When the older man held out a credit card to him, an expectant look in his dark eyes, Senku didn't think to question it. He takes it, and after holding his gaze for a moment, the older man walks away without a word. Senku doesn't find his voice until his father walks up seconds later.

An odd encounter, for sure. But not an unpleasant one. Senku had never felt so at ease and connected to anyone that quickly before.

The wordless understanding between two men of science, eh... ? Heh.

See you later, Dr. X.

Many, many years later, Dr. Xeno has been captured by Senku's Kingdom of Science, his hands bound behind him as Senku and his crewmates make a quick getaway in a stolen yacht.

Xeno isn't thinking about that, though; not right now. Right now he is thrilled that his mentee and him are on the same page, and have both come to the same conclusion about the one who dwelled on the moon.

They're both about to engage in an exchange of information — but Xeno has a better idea of how to go about it.

"Senku," he says, meeting the eyes of the young man who had pulled up a chair to sit directly in front of him. "Could you come a little closer?"

Senku complies, sliding his chair closer.

"A bit closer?"

Senku frowns, pulling his chair closer still. His mind wanders to that moment of their meeting, thousands of years ago... that wordless connection. Could they achieve that again... ? It would certainly be useful right now.

Their knees are barely touching now, and Senku feels a small spark of connection, the thought coming to his mind at the same time Xeno voices it. "Closer."

"Senku... ?" Chrome says, a concerned tone in his voice. Senku waves him off. He stands now, placing his hands on Xeno's thighs as he faces his former mentor.

The connection is faint — the cloth of Xeno's pants interfering with it — but it's there, and Xeno smiles at Senku. "Can you come a bit closer? I'm a little tied up at the moment."

Senku smirks, resisting the urge to roll his eyes at the pun, and leans in closer, putting his face directly in front of Xeno's.

Xeno's smile widens as he gives a small nod of approval. "This will be more efficient." Skin-to-skin contact is best, Xeno's mind supplies for him, and Senku hesitates, just for a moment.

Even if this is a ploy... perhaps it would help quell this pesky attraction he felt for the man since he had laid eyes on him at long last.

Xeno leans across the distance, and Senku is surprised at first, but doesn't pull back — especially when he feels the surge of information entering his mind as soon as their lips meet. Even if he didn't want this, the information is just too intriguing to pull away from.

(That's what he focuses on, at least — to distract himself from the other feelings that kissing his mentor brings forth within him)

He hears the shocked and surprised reactions from his friends and crewmates behind them, and he holds up a finger to indicate to them to wait a moment before trying to separate them. He reaches his hands up, grasping Xeno's upper arms to pull him closer as he straddles the man, deepening their kiss as he effortlessly offers up all the knowledge he's gathered so far on Why-man, it being met with Xeno's intel.

Everything that matched up, the details that didn't, what Xeno had been able to find out that Senku and his team hadn't yet... it was all so exciting. Senku can feel his face heating up in a fevered blush, especially when he can sense Xeno's pure pride and admiration directed at him through their connection. 

The information, the raw emotion, the physical sensations he was feeling... it’s all too much, and when they finish exchanging what they needed to, Senku pulls back, panting softly and wiping his mouth as he sits on the couch next to Xeno, giving him a look.

Xeno needs no more cue than that, and turns to the confused crewmates. "Allow me to explain. Dr. Senku and I were merely exchanging information in the most efficient way possible." When met with the crew's dubious looks, Xeno chuckles. "Have any of you heard of the concept of soulmates?" At Luna's spit-take, Xeno smiles. "Well, some of you have. It turns out that there's a scientific principle behind the phenomenon — it's referred to as the instinctual pair bond. It developed to improve the chances of human survival; if two humans have similar enough brain waves, even small physical contact can enable their electromagnetic frequencies to connect, transferring information to one another in an instant-" He pauses, seeing that even Francois is struggling to translate Xeno's words.

He sighs. This is when Stanley would have told him to sum it up already. Ah. I miss him. Xeno hopes Stanley isn't worrying too much about him — he's having a great time, really. He frets at the thought of him anxiously smoking cigarette after cigarette while he searches the waters. Though he isn't Xeno's soulmate in the technical sense, he is in every other way, making up for what Xeno lacks — street smarts versus book smarts; instinct versus logic; skill versus intellect. He really did love him.

But this new bond, with his mentee who was on the same wavelength as him in more ways than one? It was downright exhilarating.

And why couldn't he have both?

Xeno tries again. "Basically, Dr. Senku and I are soulmates, and that bond has allowed us to transfer a large amount of information to each other without having to speak a word."

A gasp goes up from the gathered crew at that.

"We'll worry about that later," Senku spoke up, having recomposed himself. Xeno's speech had given him the time to parse the new information he received, and he was now able to sum it up for his entire crew in words they could understand. 

He gives a large, slanted smile. "What I just learned... is going to get you all excited."

Chapter Text

“Xeno-chan, I suppose you had an inkling that Araxá was our ultimate destination in South America, right?”

Xeno gives a small smile. “You could say that. I knew Senku wouldn’t overlook the valuable resources he needs… We’re both rocket specialists, after all.”

Something about Xeno’s words strikes Senku, and he turns subtly to watch him… and he hears a familiar metallic tink.

He whirls, and grabs Xeno by the arm, clutching it tight when he sees the magnetized screw stuck to his metal fingertip. Senku’s next words are severe. “What have you done?”

Caught off-guard, Xeno’s thoughts are open for Senku to read… the curled coil, the magnetized metal claw… a rudimentary signal.

And his mind’s-eye vision of Stanley, winking in and out...

Xeno smirks at him, closing his mind to further probing. “It’s too late now. It’s already done.”

Senku glares at him, and gives his arm a firm shove. “I need a rope,” he says, raising his voice to his crew members. Tsukasa brings him a length of rope, having it constantly at the ready in an event like this. “Tie his arms.”

“That’s a little spiteful, isn’t it, Senku-chan?” Gen says, sidling up to him. “It’s as he said, what he did is already done.”

Senku doesn’t respond, thinking over what he had seen.

The memory of Stanley… that was after we made the bikes. Why was it winking in and out? His other memories didn’t look like that…

“Morse code,” Senku realizes with widened eyes.

“Come again?” Gen says. “I think I’m familiar enough with Morse code by now, and I don’t think what Xeno-chan was doing was that.”

“Not that,” Senku shakes his head. “When we made the bikes. Hyoga put him on the tire, tied up and gagged. Facing Stanley’s gang.”

“Yes, that’s right.”

“That was a mistake,” Senku says, feeling a dawning sense of dread. “He sent Stanley a message.”

“...By blinking,” Gen says with a frown.

“Yes. And most likely… he told him where we were heading.”

Xeno laughs as he’s being tied. “Brilliant deduction, Senku. I knew you could figure it out. Just not soon enough,” he says with a wicked grin.

Senku sighs, a weariness showing in his eyes. “Just… get him out of my sight for a while.”

Tsukasa nods, and leads Xeno toward the other end of the ship. Gen gives him a sideways glance.

“Senku-chan…? This is rather unusual.”

“I just… need some space,” Senku says, before walking away from him, to the front end of the ship to join Ryusui, in hopes of some much-needed distraction.

Later that night, as the stealth ship sped away, Senku sat alone in the back of the ship, sleep evading him. 

He hadn’t quite gotten used to having a soulmate. 

Or, more specifically, existing in the same space as his soulmate.

Since the night they connected their thoughts, things between them had been… different. Near-inseparable, and nearly finishing each other’s sentences, even without touching. Their newest crew member, Chelsea, had caught on to their connection right away — in-sync besties, indeed.

But beyond their intellectual connection, Senku found himself being affected emotionally by the older man as well. Finding himself letting down his guard more than he should, and entertaining thoughts like What if we could go on the rest of this journey to the moon together? Can I make him give up wanting to become a dictator? What if… he stayed by my side?

Sometimes he could swear he felt the other man’s emotions as well, their combined excitement amplifying itself two-fold, a feeling of pride washing his way sometimes like lapping ocean waves on a sandy shore, and some feelings that he couldn’t quite name or place.

And for some reason, this betrayal by him stung Senku more deeply than any other ever had.

(Even more than the betrayal that had left him momentarily deceased.)

It made his chest ache, and made him want to act irrationally toward Xeno… both urges frustrating Senku deeply. This wasn’t like him.

While he was thinking over this, he heard someone approach.

He looks up, and sees Xeno walking toward him. His hands were untied now; after that heated moment, Senku realized how futile it had been, and let the man go again. It wasn’t like he could do more damage at this point.

Senku glares in his direction, not hiding his aggrieved expression.

“What’s the matter?”

“Just wondering why I had to have a soulmate like you,” Senku snipped.

Xeno frowns, and strides over to where Senku is seated, sitting down next to him. He reaches over tentatively, to place a hand on Senku’s arm.

“Don’t touch me,” Senku says, flinching away.

Xeno deflates somewhat, lowering his arm and straightening in his seat. “You’ve scarcely touched me since that night,” he says, feigning hurt. It wasn’t for lack of trying; he had been lingering close to Senku ever since, standing near him every chance he got, but the younger evaded his subtle movements to touch him every time.

Senku gives him a look. “I wonder why,” he says, laced with sarcasm.

Xeno reads his expression for a moment. “...You never wanted to find out who your soulmate was.”

“Nope,” Senku says. “All I ever wanted was to focus on science and getting to space. A soulmate would’ve just gotten in the way of that. They’re nothing but trouble.”

“Well… I’m not exactly against those goals,” Xeno says coyly.

Senku ignores that. “Now, in this stone world, it just makes everything more complicated. Sure, it was great at first. Sharing all that information was ten billion percent faster than doing it verbally. But… I forgot what a risk that could be.”

“In all fairness, I think I would have figured out your intentions even without reading your thoughts. They just filled in the blanks.”

Senku sighs heavily, lolling his head back. “Why couldn’t I have a soulmate who doesn’t use what I share with him against me?”

Xeno sighs too, reclining and crossing his legs. “Even if it were anyone else, that possibility would still be there, you know. People can be fickle creatures.”

“You’re right,” Senku says wearily. “Then, why does this bother me so much…”

“Everything’s more deeply felt when the person with the complimenting half of your soul is involved… hm,” Xeno muses, remembering the intense surge of joy he had felt at seeing Senku again, very much alive.

Senku turns his head to look at Xeno. “What is it with you and Stanley, anyway? Is he your soulmate, too? Can you have two?”

“No. Though he’s my soulmate in every sense but literal. We’ve been the best of friends since I was ten years old… longer than you and some of your friends have been alive,” Xeno says with a fond smile. “Even a soulmate is no match for that. We may have chemistry, but he and I have history. I can’t so easily choose you over him.” 

Xeno pulls his gaze away from Senku’s, his crimson gaze making his own resolve waver; a part of him strongly wanted to make just that choice. “Just because two people have an instinctual pair bond doesn’t mean that they are the only right ones for each other,” he continues. “Compatibility has far more factors than that. A pair bond like this had its use in the prehistoric age, but in this new age of science, we can choose our partners for ourselves, on our terms. Us being soulmates doesn’t change a thing, Senku,” he says, while feeling a pulling yearning somewhere in his chest that told him it very much did.

“You don’t really believe that though, do you, Doctor?” Senku says with a smirk.

Xeno sighs. “What gave it away?”

“You couldn’t hide how excited you were about it when we touched on that old boat. How you wondered what we could do if we were partners,” Senku replies. “And the vibes you’re putting out right now? They’re making my skin rot.”

Xeno gives a scoff, used to Senku’s sense of humor by now. “Do you hate it? Having me as your soulmate?”

Senku thinks on that. The answer wasn’t a simple no or yes. “...It’s uncomfortable. Like some force of nature is pushing us together. I want to control it, not have it control me.”

“That’s understandable,” Xeno nods.

Senku looks at him then. “How did you block me from reading your thoughts earlier? I didn’t think that was possible.”

“I didn’t know it was possible either. I merely imagined a brick wall between myself and your mind, as a test. I suppose imagining any kind of barrier would work just as well-”

Xeno’s words were cut off, by Senku’s lips on his. Stunned at first, he quickly takes advantage of the situation, softening his lips and matching Senku’s movements. Before their kiss deepens much more, Senku pulls away.

“Well?” he asks, wiping his mouth with the back of his hand. “Did you get anything?”

Xeno blinks, bewildered, a pink hue now coloring his cheeks. “No. Nothing at all.”

Senku smirks. He had been imagining Tsukasa brutally attacking Stanley, while envisioning putting a large door between himself and Xeno’s mind. If he didn’t react at all to that, then it was likely he was telling the truth, and the technique worked. “Looks like your theory holds up, Doctor.”

Xeno smiles. “Feel like you have more control now?”

“Yeah. Takes a lot of mental effort, though.” Senku leans his head back again. “I’ll manage.”

Xeno’s smile turns wan, as he looks away too. “It’s understandable that you distrust me. Especially now. It would be unwise not to.”

“Yep.” Senku peers at him from the corner of his eye. “ You seem to trust me a little too much, though.”

Xeno smirks. “You know that’s been a strategic decision on my part. A wise one as well, as you’ve kept me alive and well thus far.”

Senku looks at him a moment, before looking away again. “I don’t let anyone die on my watch, if I can help it. Could you say the same?”

“Fair point,” Xeno says with a shrug.

“So… you’re really determined not to let… this,” Senku says, waving his hand in the space between them, illustrating the invisible connection between them, “influence you at all, huh?”

“That’s right. I’m a man of science, and science will be what decides this battle, once and for all. The fate of the world, our countries… and us. It all hangs in the balance right now. I’m not giving an inch in this fight, as I’m sure you’re not, either.”

“You’ll put off the issue of us ‘til then, huh?” Senku grins crookedly.

“Naturally.” Xeno stands then, and looks back at him. “I’m giving this my all, Senku. You had better be giving it yours, as well. And in the end, when there is a victor… we’ll decide then.”

Senku grins at him. “Alright. Now I’m even more excited. Just don’t let Stanley put any more holes in me, eh?”

Xeno chuckles. “I can’t promise that, unfortunately. But… I’ll try.”

As Xeno walked away, bidding him goodnight, Senku felt more at ease than he had all night.

In the face of all these pesky feelings, we’re placing our bets on science, huh?

He smirks again.

How exhilarating.