Serotonin {Senku x Reader}

By _sxtsunai_

424K 21.2K 17.6K

"Sometimes reality is too complex. Stories give it form." More

Prologue
Part 1 - Rebirth
Part 2 - Senku
Part 3 - Taiju
Part 4 - Tsukasa
Part 5 - The Lion's Wrath
Part 6 - Girl
Part 7 - Friends
Part 8 - Civilization
Part 9 - Iron Age
Part 10 - Detective Suika
Part 11 - Mental
Part 12 - Good and Evil
Part 13 - Goddess
Part 14 - Worry
Part 15 - Ruri
Part 16 - Chief
Part 17 - Ishigami
Part 18 - Stone Wars
Part 19 - Cellphone
Part 20 - Light
Part 21 - Tungsten
Part 22 - Stone Day
23 - A Voice Sent Across Millenia
24 - Final Phone Call
25 - Killing Time
Part 26 - Nikki
27 - Steam Gorilla
28 - Tank
Part 29- Ukyo
Part 30- 20 Fateful Seconds
31- Lost Hope
32- All is Fair in War
Part 34 - Stone Wars: Epilogue
Part 35- A New Era
Part 36 - Nanami Ryuusui
Part 37 - Information HQ
Part 38 - Money is the Universal Language!
Part 39 - Becoming a Millionaire
Part 40 - And the Winner is...!
41 - Leader
Part 42 - Desire = Justice!
Part 43 - Protasis
Part 44 - Epitasis
Part 45 - Catastrophe

Part 33 - The Ending and The Beginning

6.2K 365 335
By _sxtsunai_

Y/n looked up to see Tsukasa standing in front of her and Mirai, Hyoga's spear gone clean through his chest. Y/n felt the panic quickly rise as she jumped out of the way, the sight before her eyes traumatizing her. 

Hyoga pushed the large man off the cliff they were standing by, but Y/n was frozen. She couldn't even think of how she had been right, or that she should be fighting back, or even trying to catch Tsukasa. All she could do was sit there, eyes wide, as she watched Tsukasa's body

Fall

          Fall

                    Fall.

A hand grabbed onto Tsukasa's limp one, and all of the sudden, Y/n snapped out of her shock. Senku had managed to catch Tsukasa, struggling to hold onto him. As Y/n struggled to get up to help him, Hyoga hit Senku square in the back, making him lose his balance.

And they fell down, down into the water.

Y/n screamed, and started running towards Hyoga, knife drawn.

"YOU BASTARD!! YOU PIECE OF HORSE SHIT! I'LL KILL YOU!" She screamed as she propelled herself towards him, only to be shoved down, looked down on by Hyoga with disgust. 

"You really are quite unsightly."

And with that, he ran off, followed by Kohaku and Chrome, but it was no use. He jumped off the cliff, landing in the water with a splash. Y/n pathetically sat on the ground, stunned. Were they.. Were they all dead? Could they have possibly survived that drop? Had she just lost her best friend, as well as the man she wanted to murder?

She felt empty.

Kohaku, Ukyo, and Chrome finally caught up, staying shocked for just a moment before bombarding Y/n with questions.

"Are you okay?!"

"What just happened?!?"

"Do you know where Hyoga went?!"

Kohaku and Chrome kept asking relentlessly before Ukyo stopped them.

"Guys! Be quiet for a moment, will you?! Go find out who caused the explosion!" He gave them both irritated looks as he sat by Y/n, giving her a pat on the back. He was gentle and calm, like a soft breeze on a nice summer afternoon. "Hey... Y/n. You know when you told me how I had been brave for staying silent so long? Well, I think you're very brave too. You did everything you could in that moment. So, no matter what happens, it's not because of you."

"I..." Y/n felt her lip tremble, her emotions coming back as if it were a tornado, swooping her up in her feelings. No, she couldn't. Not right now. If there was any chance any of them were alive, she needed to find them. She took a deep breath. Be logical. What would Senku do?

"Y/n," Ukyo looked her in the eyes, noting her newfound determined expression. "You can't go off and be the hero right now, even if you want to. If you're trying to be rational, going off and dying from overexertion won't help anyone. The most rational thing you can do is stay here and help us figure out a plan. Hyoga wouldn't have done that unless he was sure the three of them would survive. They have to be alive, right?"

Y/n nodded. She felt useless again, which only made her want to cry more. Not yet. She still had to help. She was still useful, even if she couldn't fight. She pressed at the bone right under her eyes, a pressure point to calm down, then took a deep breath to clear her head.

"Right. For now, the best thing to do would be to find who blew up the cave. I'm almost certain Homura found her way out somehow, since she works closely with Hyoga. If by some chance Senku is unharmed and Tsukasa is alive, they might be able to take Hyoga. Even if it's just Senku, he'll find some way to stall. However, it'll be the end for them if Homura finds them too. Disarming Homura needs to be your top priority. 

"After that, follow the stream with the rest of the battle team and find Hyoga. Worst case-scenario, he's already killed both Tsukasa and... Senku, and will kill us all if it means he stays in power. Hyoga might be powerful, but if you and the rest of our team gangs up on Hyoga, he'll lose and we'll be able to imprison both him and Homura. We'll go from there," Y/n instructed, to which Ukyo nodded.

"That sounds like the best course of action," he said, gathering his bow and quiver. "And Y/n?"

"Yeah?"

"Stay strong," Ukyo gave her a little fist bump and a smile before standing up and running off to join the others. Y/n smiled, feeling a little more confident, before the overwhelming urge to cry came back. Mirai, who had been sitting a few feet away alone, looked at Y/n with wide eyes.

"Are you.. Some kind of leader here?" She asked, right before Y/n could let herself have a mental breakdown.

"Wh-What?!"

"I-I didn't mean to assume things! It's just, you looked very sure of yourself, and you came up with that plan like it was nothing!" Mirai exclaimed nervously, "So I thought you might be some kind of authority figure here..."

"...Oh. Well, unfortunately I'm not," Y/n smiled a little, "Now, if you'll excuse me, I've been on the verge of sobbing my eyes out for too long, so I'm going to do that now."

And right as Mirai tried to offer comfort, Y/n followed through on her word, tears spilling from her eyes and choking on a sob. As a means of consolation, Mirai hugged her and patted her on the head, only to feel the same overwhelmed feeling as Y/n, and the two ended up comforting each other as they cried. Y/n, after a while, calmed down and wiped her eyes, feeling much more relieved.

"Heh... Y'know, I can see why Tsukasa wanted to revive you so badly.. You're a great little sister," she laughed, rubbing her eyes. Mirai giggled a little, despite everything. She gave Y/n a big hug, trying to keep herself from crying anymore now that Y/n had stopped.

"Do you have any siblings, Y/n?"

"Ah... Unfortunately not. I always wanted a little sister though," Y/n smiled, remembering when she was a small child, begging her parents over and over for a little sister to play with. Mirai smiled with her, letting go of her.

"Well... I can be your little sister, then! And Tsukasa can be your big brother," Mirai giggled. "We'll be a big, happy family then!"

Though both Y/n and Mirai knew the painful truth about Tsukasa's fate, Y/n kept up a cheery tone and patted Mirai on the head.

"Yeah, I'd like that," Y/n affirmed, then gave Mirai a look of surprise. "Wait, does this mean I can call you Imouto(little sister)?!"

"Yeah! And I'll call you Ane(big sister)!!"

"I love you already!" Y/n squealed, feeling a lot better for the time being. "Heh, that means Tsukasa is Ani(older brother). I miiight have to wait a while on that one."

"Oh? What happened between you two?"

"Oh, he just tried to murder Senku and was at war with him for a year or so," Y/n grinned, to which Mirai got a scolding look on her face.

"Seriously?! Oh, I am so going to lecture him when he gets back!" Despite her energy, there was a lining of sorrow to her tone. They both knew this lighthearted bonding was only to distract them from the fact that their loved ones could very well already be long gone.

If Tsukasa came back at all, he could've very well have bled out a long time ago. Y/n's wound wasn't nearly as severe, but it had still affected her stamina and endurance immensely. Mirai seemed to give up a little, her smile faltering.

"...Y/n. He's not going to survive, is he?"

"I... I doubt he will, honestly," Y/n sighed, then offered an optimistic smile, "But you never know. Your brother was called the 'strongest primate highschooler' in the modern world. When we first revived him, he killed a whole pack of lions with his bare hands to save us. He's a strong guy, so I wouldn't lose hope completely just yet. Even if he doesn't make it on his own, Senku will find a way."

"He did all that? Tell me more, please!" Mirai looked at Y/n pleadingly, and so Y/n continued to tell Mirai all the good things about Tsukasa before the Stone Wars, for so long that she had lost track of the time.

"...And he hunted all this food for us! Honestly, I don't think I had been fed better since the modern era then," Y/n smiled, feeling nostalgic. "Despite everything, he's truly a kind and caring soul. He's very loyal, and true to his word, not to mention he'd do anything for you."

"Well, I'm glad he's a good person," Mirai said wistfully, "I just wish I could've talked to him more..."

"I'm sure you will, Imouto. Tsukasa wouldn't give up that easily. Especially not when it comes to you."

"Yeah... Thanks, Ane," Mirai smiled, sniffling. Y/n felt a pang of sadness for poor Mirai. She gave the small girl a big hug as the sun started to rise. They had really stayed up all night waiting. As if the universe took pity on Y/n, right as she thought that, she heard multiple footsteps headed towards them. 

Both exhausted and weak, Y/n stood up with Mirai's help to see Senku and the entire battle team (who were carrying Tsukasa), walking over to them, a tied up Homura and Hyoga walking behind them shamefully. Y/n grinned, overwhelmed with joy to see everyone— but especially Senku— safe and sound. Once they were close enough, Y/n let go of Mirai to run to Senku, throwing her arms around him as her legs gave out, knocking them both down.

"Senku!! You won, and you're safe! You're not hurt, right?! I'm gonna murder Hyoga if he hurt you! Actually, scratch that, I'm gonna murder him regardless!" Y/n cried, still holding onto the poor scientist for dear life.

"Where was all this energy before?! Also, get off of me! You're heavy!" He barked back, but Y/n was too happy to bother listening. With a little help from Kohaku and Kinrou, they managed to help Y/n back up, carrying her.

"Wait! Take me over to Hyoga, I need to kill him!"

"You're not killing anyone in your state," Kohaku chuckled, "You should just be happy, anyways. It's finally over."

"Kukuku, you're wrong. You should be saying, 'at last, it begins!'" Senku exclaimed, Yuzuriha's Kingdom of Science flag in hand. Y/n grinned, pumping her fist in the air.

"Yeah! At last, it begins! This moment forward marks the end of the tedious Stone Wars!"

***

The next few days for Y/n were fairly unexciting, though, she actually enjoyed it. For once, there was no task at hand which had their lives on the line. It made her overjoyed.

Mirai kept her company during most of her recovery. Y/n would tell her stories as Mirai would make them both flower crowns and braided Y/n's h/l hair. Y/n felt like she really had a younger sister, which she now considered Mirai to be. 

As promised, Yuzuriha and Taiju forced Senku to visit Y/n for some of the 'nostalgic bonding' that she had yelled for over the phone. They ate together, talked about the modern era, and ultimately had a fun, sentimental day stuck inside with no work, much to Senku's disdain. They stayed up, laughing into the hours of the late night, until Senku insisted that Y/n needed her rest and ushered Yuzuriha and Taiju out.

Of the long few weeks, Y/n also spent a lot of time with Gen, who often came to visit her out of boredom and because he "missed her pretty face." Together, they gossiped about the happenings of the Kingdom, new romances and the like, as well as Y/n learning new magic tricks in return for stories, which she happily obliged to.

Then, there was Senku. He was busy most of the time, planning out new projects on blueprints, but whenever he had free time, he would come and bring ramen and project drafts to share with Y/n, which she struggled to understand, but enjoyed her time with him nonetheless. There were even times where she insisted he stayed the night, and so he did, working on sketching out ideas by a dim lightbulb while Y/n fought to stay awake, and inevitably failed to do so every time.

All in all, Y/n was happy for the time being, though there was still a lot she wanted to do, it would have to wait. She still wanted to take her revival fluid and revive Val, that way she could meet for, really meet her. She was also concerned about information being lost during her recovery, but Ukyo had promised her he would document things for her, so she felt she could rest at ease. Though, as she had joked, she doubted the quality of his work could match up to her own "supreme writing abilities."

And so, on one morning during her recovery, Gen came to visit her yet again, bringing a little bouquet with him, which was new. He handed it to Y/n, smiling innocently.

"Flowers, for the lady," Gen chuckled as Y/n smiled and set them aside. "I thought you could use something to decorate your space a little better~"

Well, he had been right. The small hut that Y/n resided in was drab, lacking much color or decor. In fact, it was barely big enough to fit her bed, a desk, and a shelf, which she stored spare clothing and her journal on. Y/n took a spare jar which had been lying around and set the bouquet in it, placing it on her shelf once she did.

"Well, you weren't wrong. It does make the space look nicer, doesn't it? Anyways, why are you here, mentalist?"

"Ehh? You're so cold, Y/n, and even after I brought you flowers~ Fufufu, just kidding. I'm here because I noticed you and Senku spending an awful lot of your time together. Are you perhaps... and item yet?"

"You came to gossip, then," Y/n chuckled and flopped down on her pile of blankets, staring at the ceiling. "You're forgetting one thing: I'm not confident with stuff like that. I'll probably be in my forties before I even consider confessing, y'know."

"I'll take that as a no~" Gen sat down at the foot of her bed, grinning. "Well, you gotta do it sometime. You can't wait forever, or you'll never get closure~"

"Well, I mean, I did promise him I'd tell him something important once the war was over, but I didn't specify it was about anything to do with my feelings."

"And why did you wait this long to tell me?!"

"Because it's none of your business?"

"So mean~" Gen pouted. "Well, he'll probably be expecting you to tell him something, if he hasn't already figured it out yet. That, or he'll just assume you forgot~"

"Ugh, I would love it if he just did that," Y/n sighed. "Then I wouldn't have to tell him anything. I can just say it's not important anymore, right? Then I'll get over him, easy peasy. I'll live a happy, single life with ten cats and a library and that'll be the end of it. The end, story over."

"That's so boring though!!" Gen whined, laying down with her. "We live in a stone world. You've fought people several times your size, won a war, went down into acid pits to make sure your friends stayed safe, and you're too afraid to confess your feelings to that stupidly logical scientist?"

"Yes," Y/n scoffed. "What if I lose him as a friend? We're not exactly living in a world where I can just cut him off and be done with him. I'd still have to see him every day!"

"You underestimate Senku's maturity, love," Gen sighed. "Worst case-scenario, he rejects you and you both go back to the way things were. Even if you get rejected by him, I know for a fact that he wouldn't want to lose you as a friend."

"Right..." Y/n exhaled, then sat up. "I shouldn't be so worried. But, can I ask you something?"

"Anything, dear~"

"Why are you so insistent on me confessing to Senku? I mean, if I'm as cute as you say, wouldn't you want me all to yourself?"

"There's a number of reasons, dear," Gen chuckled. "The main one being you've never even remotely shown a romantic interest in me. I mean, seriously, it's like you only have eyes for Senku."

"I do."

"Ah, such a pity. Well, I suppose normally I wouldn't care, but you've forgotten one key fact: You and Senku are my dearest friends, and I want you both to be happy. That being said, you two make each other happier than anything else! And you'd make the cutest couple."

"Are you saying... He might have feelings for me too?"

"Hmm? Well, I wouldn't know."

"God dammit, you're a mentalist! Can't you at least tell whether he might feel the same?!"

"Senku's a very reserved guy, Y/n⁓ It's almost unfair of you to ask me to try and read someone so closed off..." Gen grinned slyly, "Is what I would say if I were a crappy mentalist."

"So you do know?!"

"Well, not exactly. With you, it was easy to tell— you're an open book. Senku's a bit more complicated than that, though. He obviously cares about you more than others, I can tell that much, and I know that it'd take more than a love confession to change that for you two."

"...How can you tell?"

"He spends most of his free time with you, Y/n. That's just common sense. I mean, you must be very important to him if he's okay with you staying in the same room as him while he works in his free time, y'know?"

"That's nonsense! I'm just there for him to bounce ideas off of!"

"Well, you certainly aren't as experienced in science as, say, Chrome. No offense to you, of course," Gen laughed sheepishly. "If you really are there to help him work, why wouldn't he have more geniuses join you? After all, the more the merrier, right? Logically, it'd be more efficient."

"You're... Right."

"Of course I am, darling. Either way, you both will be fine," Gen stood up, stretching a little before walking towards the door, "Well, I'll let you think about it. Anyways, don't be so dismissive of the thought that he doesn't feel the same, because it's possible⁓"

"Right..."

"You're overthinking it already, fufufu. Well then, bye for now⁓" Gen said cheerily as he left Y/n's small hut.

Was what he said really true? Taking his words into account, Y/n did suppose that the pros outweighed the cons. And she did promise Senku she'd tell him after the stone wars were over, which they now were. Would he find it too odd if she just told him it was no longer important? Probably. Y/n sighed.

How would she even go about confessing? It wasn't something she'd just want to bring up casually— in fact, she'd want to make her confession something cheesy or romantic, even though Senku wouldn't like it nearly as much as she would. 

She didn't know what to do.

<><><>

HI

The new chapter is finally here!! I know it wasn't all that eventful in Y/n's perspective, but then again, she's kinda injured so there's not much she can do. Either way, I'm loving the idea of Mirai being like Y/n's little sister anD I SWEAR TO GOD IF I GET ALABAMA COMMENTS ABOUT TSUKASA X Y/N I'm gonna laugh my ass off. 

Anyways, next chapter is gonna be kinda sad, so grab your tissues and blankets if you cry easily ✌😗

Also, now that we have 35k reads (which still blows my mind) I feel like I should have a name for y'all, so gimme some suggestions for what you all want to be called!

I edited this late, so if there's some typos please forgive me. Also, I noticed some mistakes in previous chapters, so you might get the notification that it got reposted. 

Uhhh but that's all, so stay safe and have an amazing rest of your week!!

-Bitter ❤

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