My Own Science (Dr Stone Senku x reader)

Penpals

"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.