"You couldn't just, you know, ask me." Senku commented. "I would've gave you his email, I wouldn't have cared."
"I was thirteen dude!" you glared at him. "You always interrupt me when I tell a story - You know the good part's about to start!"
You wanted to sass him a little more, but with Luna right there, you didn't want to show too much banter.
"Right, I'll stop now." he leaned back a bit and gestured for you to go ahead.
You huffed and continued.

'Dear NASA scientists, I'm looking for a certain Dr. X. My friend has been talking to him for years and didn't tell me anything about it so now I'm seeking revenge and I want to steal his American friend from him. Also, the name "Dr. X" sounds very evil, so if he is indeed evil, let him know that I would still like to talk to him, so that I can threaten him to leave my friend alone. For clarity sake, the entirety of this email is a threat. Thank you in advance. Best wishes, (L/n) (Y/n), 13 years old, Japan.'
Yes, your English has always been impeccable. With a proud smile, you clicked send.
Meanwhile, in an incredible coincidence, Xeno was at his computer. He's just finished reading Senku's reply when he received a notification in the NASA's general email address. He chuckled to himself as he read your message. He had a suspicion before that Senku was actually an adult, but given what you wrote, he figured he really was just a kid, just like you. He usually wouldn't reply to children (Senku being the obvious exception) but he was simply amused by you, that plus the fact that you were Senku's friend intrigued him a bit. He replied, half-joking:
'Dear (L/n), this is Dr. X speaking, although I understand your suspicions and will call myself by my real name in your presence: Dr. Xeno. Rest assured that I have no evil intensions discussing with your friend. It is merely an elegant exchange between two passionate scientists about rocket science. I do admire your dedication and hope to rest on good terms with you so as to not suffer your wrath. Kind regards, Dr. Xeno.'

He smiled to himself and sent it. You flinched in the middle of cooking your dinner when you received the notification, you didn't expect him to reply so soon. You read it and wrote:
'Dr. Xeno, my deepest thanks for not being evil. Now I can return to my initial plan and steal you from my friend.'
'Dear (L/n), sadly I very much enjoy my exchange with Senku and wish to continue. But we can still have a discussion you and me.'
You thought for a moment.
'Dear Xeno, I have decided to keep our messages a secret. So that, after we become best friends, I will tell Senku and the look on his face will be the sweetest revenge of all. So please don't tell him, okay?'
Xeno quietly laughed.
'Dear (L/n), you have my word.'

A few days later, the conversation continued.
'Tell me (L/n), I heard of Senku's friend lending him a hand with his experiments. Are you a science enthusiast like Senku, or are you also assisting him with the more physical work?'
'I am helping him with the best of my abilities, but I'm no scientist. I do lend him musical instruments for him to study and reverse-engineer. Although I refuse that he touches my harp, it is far too ancient and delicate to go through the risk of breaking it.'
'You must have a lot of instruments if you provide them for him. Are you from a family of musicians?'
'No, I'm the only one in my family besides my grandpa who used to be a professional violinist. My parents buy me all the instruments I want so they're easy to get.'
'What instruments do you have?'

It was then that you forgot about your plan and went on a tangent about your music stuff and the shenanigans you and Senku went through because of it. Like that one time someone stole your precious lucky gold harmonica and it turned out that that someone was a yakuza, so you both infiltrated a venue where a wedding was happening and that the yakuza was attending, talking to each-other via those plastic walkie-talkies that you bought on the way for five bucks at the supermarket's toy section. But when you finally cornered the yakuza it turned out the harmonica was supposed to be a wedding gift and that he was broke and in debts but still he wanted to give his dear daughter a gift. And she used to also have an golden harmonica that she loved a lot (maybe it was the exact same one now that you thought about it), but he had to sell it for money and lied about it saying it just disappeared. You were touched by his story so you let him have it.
'And the two of us went home just in time for Christmas.'
Xeno chuckled as he read your email. He wondered if you were lying, but on the other hand, if it was true, then he would understand why Senku kept hanging out with you even outside of anything science-related: You were very entertaining to be around. He was curious and asked you to tell him some other "interesting" story (an elegant way of saying that they were batshit crazy), and you happily obliged.

For a long while, this was the type of conversations you'd have with him: just telling him about your crazy adventures with Senku and him having fun reading your stories. And sometimes, he'd tell you about his wacky colleagues too. It was nice and fun.
Then one day, he stopped replying. You were used to wait a couple of days, maybe a week for his response, but not four whole months. When you saw Senku checking his phone for the third time today and frowning, you figured Xeno wasn't replying to him either. You sent him several emails telling him that you hoped he was okay and doing well, but still no reply. You were getting worried. Did something happen? What if he got tired of talking to kids?!
Just when you started your internal freak out, he replied:

'Dear (L/n), I apologize for not reaching out to you for these past couple of months. I appreciate your concerns and assure you that I am fine. If not a bit ticked off; You see, in a meetings with my higher ups, I've proposed to take our newest project to a new direction, something that could've greatly advance our researches and could've been very beneficial for future projects. Yet, despite all my proof of the contrary, they told me it would be "too risky" and that "the public liked our initial plan better and they didn't want to disappoint them". Ridiculous. Keeping up their image at the cost of precious scientific advancements, all so they can keep getting funded. It is in those times that I'm reminded that NASA isn't the elegant place I first believed it to be. During these four months I've been working in this project, the fact that my heart wasn't in it has made me a bit frustrated and so it was difficult to focus. I have sadly still not finished but have allowed myself a short break and will be able to reply sooner in the future. Again, I apologize for worrying you and hope you are doing okay as well. Warm wishes, Dr. Xeno.'

Reading his message, you could tell he was still worked up by all of this. You could relate to being forced to do something you don't want to, especially when it's in the realm of something you usually love. The times your parents forced you to enter stupid competitions when you were younger popped in your mind, forcing you to play a piece exactly right and not putting anything extra into it or else it'd be labelled as "bad" and sometimes "tasteless" (you huffed just thinking about it). You checked the world clock on your phone to see what time it was in America. Because where you were, it was the middle of the afternoon, and you have yet to get used to the different time zones.
'2:30am.'
You felt your chest tightening with an expression of sad empathy on your face. You quickly searched through your computer and found a track you finished a while back. You attached it to your email and typed:
'Xeno, thank you for telling me about this. I know how it feels when the thing you love becomes bitter, I hope you feel better soon. I won't take too much of your time, you must be tired. I'll just give you this track I made (I recorded it in an empty parking lot), I hope you like it. Your friend, (Y/n).' you stopped, realizing you just wrote your first name. Blushing, you kept typing. 'P.S.: just (Y/n) is fine.'

Meanwhile, in his dark apartment only lighted by his computer screen, Xeno read your email and opened your track. It started with just the muffled sounds of the city in the background, then the music started, the reverberation of the instruments plus the slow tempo made it all very calming. It was very lofi-ish, but somehow, Xeno could tell you made this music with a mindset similar to his at the moment, maybe even the exact same. It was sad yet serene. He leaned back and listened, drinking his warm coffee with his eyes closed.
It was the first time he listened to your music, and he realized: you were good, really good.
'Dear (Y/n), thank you.'

"Did he tell you about it?" you looked at Senku.
"Nope." he casually said. "He just replied to me as if nothing happened and I was just glad he didn't ghost me."
You looked down for a moment, unwillingly feeling happy that he opened up only to you that day. You shook off that feeling and kept going.

After that, the discussions you had with Xeno didn't have anything to do with Senku anymore. It was just the two of you, talking about each-other's lives. You'd send him some other tracks of yours from time to time or you'd recommend some songs and albums for him to listen to. (Though, he always said he'd listen to them later because he was busy, by now you suspected him to have never listened to anything you've sent him.) As the years passed you've indeed developed a crush on him but it never came up in your conversations (except maybe a few invitations for like a friendly date without saying it'd be a date, but they never led to anything), so it naturally went away with time. You weren't upset, he was an adult after all and you were, what, fifteen at that point?

'I'm curious (Y/n), what do you think would be an appropriate instrument for me to have?'
You thought for a moment.
'The pipe organ for sure.'
He chuckled.
'Is this a callback to when you thought I was evil?'
'Maybe! The thing about pipe organs is that they are the most difficult instrument to play, so you have to take years and years just to play correctly. So if you were able to play it while still working as a NASA scientist, you would be a complete freak not gonna lie. Really evil energy!"
'Do you know how to play?'
'Xeno please, I'm insulted. Of course I know how to play the pipe organ!' you both chuckled. 'Although, I only learned how to play Bach's Fugue in G minor because it's my favorite one. After that I didn't want to bother. For real though, if I could give you an instrument it'd be:' you looked around your big instrument room, which had little furniture and mainly just instruments. 'an otamatone!'

"A what?"
Xeno made a quick google search and frowned slightly when he saw the instrument. Thinking you were joking again, he kept reading.
'A lot of people say they have an annoying sound, when I brought mine to class people would get mad and ask me to stop playing. I think they're underrated! They sound like a tiny robot, though I guess you need time to get the hang of it: like violins, there's no indication where the notes are. Still they're a lot of fun! And you could put it on your desk, it'd make for a neat decoration.'
'I'm still a bit confused as to why you'd say this instrument would fit me.'
'I don't know, it's a feeling in my heart!'
Xeno sighed, smiling.

"And yeah, it was fun." you said. "Well, except that one time when it got kinda weird. That was the time I realized he could be pretty shady..."

'(Y/n), today I was asked what I would do if I were to suddenly to go back to the stone age. I'm curious to know what you would do in this situation.'
"Uh..." you thought for a long moment.
'To be completely honest, I have no idea. I have zero survival skills so I would probably die within days. What about you, what did you say?'
'I would re-create weapons of science from scratch and rule as a dictator. And in that primitive world, we would learn that science truly is power.'
"Huh?" you blinked twice, taken aback by his answer, and kept reading.
'And, if it cheers you up dear (Y/n), know that you wouldn't be useless in a stone world. On the contrary. Tell me, have you heard of soft power?'
"Soft power...?" you mumbled to yourself.
You remembered your teacher mentioning it in your geography class, but obviously you weren't paying attention at the time.

'Countries use it to put other countries on their good side via their cultural values. Japan used this soft power after World War 2 to rebrand itself, which is why it is now associated with colorful, crazyness and cuteness. A more recent example would be the growing popularity of Kpop: because of it (whether intentionally or not, I only know about it from a colleague of mine), South Korea became a very idolized place despite its many issues. But to go back to our stone world hypothesis: with your skills and knowledge, you would be the best musician on Earth. People would love you and hold you and your opinion on a high pedestal. To put it simply: soft power is used to 'seduce' people into cooperation using entertainment. In a stone world, you yourself would be the most powerful soft power of them all. You'd be a necessity to keep the people docile.'
"Okay...what the fuck?" you said to yourself, weirded out for sure.
'Well, that sounds like a lot of responsibility.' you replied, not wanting to continue this conversation. 'No offense but I'm good just being a casual musician, in my house made of cement with my electric heater and all of my twenty-first century things.'
Then he went 'haha of course, anyway' and changed the subject as if he didn't just say something completely insane.

"Well, not that I say this out loud," you said. "I should've seen this coming, the whole 'serve under me' thing."
"So..." Luna said, making you turn towards her. "You're a musician?"
You nodded.
"That side project of his was a bunch of instruments."
"I see..." she fidgeted a bit.
You tilted your head. She looked like she was really curious about something but was really trying not to show it and instead making it very obvious.
"I-I hope your mind cleared up about him now." she said, acting like she wasn't very interested.
"Not really." you paused. "There is one thing I know for sure now:" you looked at her with a serious expression. "Your science leader is a hypocrite."
She blinked twice, not understanding. Then left without saying a word, which you found suspicious and you wanted to keep an eye on her but then Magma started to make noises.

"That, is, in-sane!" he exclaimed. "Don't tell me you kept talking to him after that!"
"Okay I won't."
"...Did you?"
"Yes."
"God dammit (Y/n)!"
"W-well, the subject was never brought up again! How the hell could I have predicted his dictator fantasy would come true?!"
"Your little tale gave me an idea." you turned to look at Senku. "We have a thing Doc Xeno doesn't have that'll be sure to be our ace in the hole." he paused and smiled. "The medusa!"
'Oh thank god I thought you were gonna say me.' you sighed through your nose. 'Because I am done playing bait!'

"C-Can we use it again?!" Ginrou asked.
"Nah, battery's dead remember?"
"Then how is it gonna help?!" Taiju asked.
"Like a bluff maybe?" you suggested.
"More than anyone, Doc Xeno knows how strong scientific weapons can be. And he's the type to take over this new world with 'em." he explained. "The medusa is a piece of super science, so there's no way he can ignore it."
"Haha! So it doesn't matter if we can't use it ourselves!" Ryu snapped his fingers. "Because this enemy is a talented science-user, we can make out the medusa to be some ultimate invincible weapon!"
"Oh! So I was right!" you happily pointed at yourself. "Nice!"

Just then, Namani called via the communication pipes.
"I was about to send out the hourly broadcast, but when I went to tinker with the equipment, it started making weird noises."
Senku switched to another frequency, the sounds was indeed not pleasant to the ear. Though thankfully, nothing like one of 'why-man's messages.
"It's scrambled." Senku said. "A message sent via an actual encryption device."
"Passing secrets to each-other?! Not fair!" Taiju exclaimed.
"Must be Xeno and his people!" Ryu added.
"Can't we crack the code?" Nikka asked.
"Not without a spectral analyzer..." Senku thought.
Meanwhile, you felt that something wasn't right.
'If they give each-other coded messages, then they must've gotten new infos.'
You and Ryu immediately looked at Luna, she was looking out towards the trees.
'Wait...' you followed her gaze. 'Then-'
"A sniper!!!" Ryu shouted. "We've got a sniper!"

While everyone panicked and took cover, you just stood there. You figured you and the other girls were safe. After all, snipers are usually for one single target, so Dr. Taiju would be the-
"A sniper?" you just realized, your heart dropping.
They intended on killing your science leader. Wait, no. No way! There's no way he'd go to that extreme! Killing a teenager? That's just insane! Right? Right?!
And those new informations must be...
Your heart pounding, you looked over at Senku, who took cover, and saw him intensely shaking a bag like his life depended on it. Because his life did depend on it. Without thinking, you ran towards him as fast as your legs could. You crouched next to him.
"Senk-"
Then, the bullet went through the ship's wood, through the bag, and through Senku, some of his blood spilling on your clothes. Pale as a sheet and frozen with shook, you watched as his body fell over backwards. And because bullets are faster than sound, only then did the loud bang rang in your ears.

Under direct orders from Xeno, Senku has been shot.