Growing Pains

Haikyuu!!
F/F
F/M
M/M
Multi
G
Growing Pains
Summary
Sugawara has a baby sister and that baby sister is YOU!The boys at Karasuno are all super protective of their senpai's sister which leads to some issues.Tying to navigate finding your own way and establishing boundaries with your friends and family can be tricky but when you throw in a guy they don't approve of into the mix it can turn out to be a little hellish.Bonding over your nerdy backgrounds you find yourself drawn to side of Terushima the boys did not get to meet.He's not perfect but he's fucking adorable much like yourself.Your best friend Inuoka Meiko and her boyfriends try their damndest to help you around the prying eyes of your friends at Karasuno.Chaos seems to follow
Note
HOWDY! I hope you enjoy this chaos!!I just really love the potential of Terushima and I think he deserves a slow-ish burn bc like he's absolutely a disaster bi and maybe a lil bit of a hoe but he's such a sweet dork too so like.... character development????
All Chapters Forward

Who Needs Instructions?

You toyed with the thick cable-knit sleeves of your sweater anxiously. "You cold," Akaashi asked. "No, I'm okay," you reassured. "You nervous to see the boy," Akaashi asked. "No," you said defensively. He nodded maintaining the deadpan but you could see the mischief in the cheeky little shit's eye. "Shut up," you grumbled, pouting. "I didn't say anything," he defended.

"Sunshine," a voice called before you could retort. Your head shot up to spot Terushima. Cuffed mom-jeans and a flannel shirt over a turtleneck. Admittedly the fitted black turtleneck looked very nice as it hugged his muscles. You glanced down at your own sweater and looked back at his flannel, to see you were both wearing the same color blue. "Was the matching planned," Akaashi commented. Terushima broke into a fit of laughter as you both answered, "No."

He pulled you into a tight hug, "As promised for making you watch Your Lie in April." "You finally got her to watch it," Akaashi asked. "Yeah and I cried like a bitch! Just like I said I would," you defended hugging back. You pulled back and turned, "Proper introduction! Akaashi Keiji this Terushima Yuuji and Terushima Yuuji this is my roomie Akaashi Keiji. We're all second years. So is Mei." "Nice to meet you Terushima-san," Akaashi greeted politely. "Likewise Akaashi," Terushima greeted playfully.

He seemed to be factoring in the response from Akaashi before he proceeded. Like always his mind seemed to be racing faster than his mouth but slightly disjointed.

"Bokuto and Mei should be back from the corner store by now," you thought aloud. "Lead the way then," Terushima suggested.

~~~~~

You walked in with Akaashi and Terushima. Bokuto perked up excited. "Bokuto Koutaro and Inuoka Meiko," you shared before motioning to Terushima, "Terushima Yuuji!"

"Dude! Your hair is sick! Did you dye it yourself," Terushima asked as he excitedly examined Bokuto's head from afar. "Yeah! With Akaashi's help for the back," Bokuto shared proudly. "It looks so fucking dope! You kinda look like a horned owl. It's cool fucking look," Terushima gushed.

You could practically see literal stars in Bokuto's eyes. Bo turned to you declaring, "He stays forever." Terushima looked a little shocked to get such a positive response. "I told you that you're charming," you teased. His cheeks grew a bit red. You smiled at his reaction as he started stammering before scratching the back of his neck sheepishly.

~~~~~

You all sat in the living room as the group had started talking before going into the topic of volleyball. Terushima's brows knit together for a second as his mind seem to start racing during Bokuto's story. You glanced over confused by his reactions since it was one you had noticed he gets when he sees something that shifts information he already has.

The boy's brain seemed to never stop. He had been, seemingly, trying to suppress his constant fidgeting the whole conversation. You also weren't sure if your constant nonverbal checking in on him was helping or not.

Bokuto finished his story and Terushima questioned, "I- you don't have to answer! Uh- I just- I keep noti- um... are you guys- I don't mean like- it's totally cool if you are I have no issu- um," Terushima stammered. "Just ask it," Meiko cut in. Terushima bit at a hangnail before asking, "Are the three of you, like ...together?"

You looked at his genuine and nonjudgemental expression of curiosity starkly contrasting the looks of shock on your three friends. Mei's and Akaashi's shocked expressions both had mixes of horror.

"Did you tell him," Mei asked you. The hurt in her voice slit through your heart as you froze up panicking. Mei wasn't a trusting person. You would never risk destroying that bond you had spent years fortifying.

"No," you said the same time he did.

"She didn't," Terushima added quickly as you froze up. "Fuck! I'm sorry. I didn't think! Well did think, but not all the way through," he started rambling. Meiko eyed you both, her expression suspicious and hurt.

"I didn't um- No, no, no! She hasn't. I just noticed- I don't even know how to articulate what I noticed any more. No, she did not tell me- actually anything at all about you guys other than she really cares about the three of you. I'm so sorry! I didn't mean to. This just goes too fast so it comes out here," he said pointing from his forehead to his mouth, "And then I end up my foot in my mouth like a total jackass."

A tense silence loomed in the air for a moment as Akaashi was the first to break it with a fit of laughter. You glanced at Bokuto and Mei confused before looking back at Terushima who seemed lost.

"That's anxious, gifted-kid rambling if I've ever fucking heard it. What class are you in," Akaashi asked. Mei looked at him bewildered by how relaxed his tone was.

Terushima sighed out in relief before answering, "Year two class seven." "Bullshit," Meiko declared with an incredulous scoff. Terushima seemed to tense back up. "That's a good reaction," you noted feeling his hand slide into your hand that had been resting behind you.

"I think we have two different definitions of good," Terushima commented. Bokuto laughed nodding, "Mei-chan can be hard to read at first."

"I'm right here," Mei declared.

"I guess since you already noticed there's no point lying," Mei pointed out, "Yes the three of us are together but it's complicated because... family." "Got it," Terushima said quickly and pulled his hand from yours seeming to relax again as he pantomimed sealing his lips.

"Did you take psychology or a body language reading course," Akaashi asked curiously. He seemed to light up at the premise of having someone else at the same caliber in terms of intellect.

"I took psych this past year but it was kinda boring because I knew it all. I've kind of just been studying it in my free time for a while now but that doesn't exactly translate academically so the courses are all like two years or so behind where I am," Terushima shared.

You looked between them feeling the same curious awe as when Akaashi would debate with Mei. You were in class four with Kino and Nari but Mei and Enno were in class five. Despite being above average you knew you were rarely the smartest in the room and that was relief because people didn't have to rely on you.

But watching the gears shift in the minds of your friends who were just naturals when it came to academics amazed you. The way their faces always lit up when there was a topic they normally didn't get to discuss or debate on because they were always the only one to fully grasp the concepts warmed your heart.

"That's my same issue with language," Akaashi shared. "I got kind of bored of english so I'm hopping between French and Spanish," Terushima shared. "If you want a challenge try Mandarin, Arabic, Korean, or Hungarian. They've been the most fun to toy with but I think I'm leaning towards Korean for studies," Akaashi shared. "K-pop," Terushima asked. "Yes," You and Bokuto outed.

"Look at them nerding out," Mei said proudly before pausing, "Wait, so you studied psych and body language right?" "Yeah. I mean I'm not an expert but I'm at least decent at it," he laughed. "Then were you... aware you were scaring Kiyoko," Meiko asked.

You thought back to the conversation where Mei had asked the boys about Terushima when they thought you were gone. The chaos crew had actually gotten serious when sharing how Kiyoko felt backed into a corner and Hinata of all people had to step up.

"Kiyoko," Terushima asked. "Manager for Karasuno," you shared. He took a second before asking, "Oh! Glasses and mole by mouth. Black hair, right? Kinda short," he asked. You nodded to confirm.

"Scared," he asked looking back at Mei, "Was I too much? Why didn't she say anything," he asked. "She doesn't do well with socializing. It took like three years for her to say a sentence in front of the whole team," you shared. "Oh fuck! I completely miscalculated. I had guessed she was more like Meiko," he shared. "Way off the mark," Meiko chuckled.

"Ah fuck," Terushima muttered resting his forehead to your shoulder. "That's so fucking bad," he complained seeming to cringe before sitting up, "I did the totally strai- fuck boy flirting."

"What was that," Bokuto asked teasingly. "What was what," Terushima a little panicky. "Totally straight," Meiko questioned. Terushima did finger guns with a slightly stressed expression you had seen Kuroo, Noya, Akaashi, and Sugawara all do a million times.

"You're bi," you asked. Terushima's head whipped to you wide eyed. He started panicking. "Disaster bi," Meiko chuckled. "Y-you're not weirded out by that," he asked.

"You have seen who her three best friends and soon to be flatmates, right," Bokuto asked. "Yeah I'm like, the boring one, even Koushi's bi," you laughed off. "You could never be boring sunshine," he replied earnestly.

"This was fun but my brain hurts I'm going to go to sleep," Bokuto declared. "Night bo," you called after him as he pressed a kiss to Meiko's and Akaashi's cheeks. "Nice to meet you," Terushima said. "You too dude," Bokuto agreed.

~~~~~

"So far, this has been the best and worst introduction of myself to other people," Terushima chuckled as you both sat on the bed.

A good deal of bickering had transpired before eventually you both said fuck it the bed is big enough to share.

"I'm sorry it was so awkward," you apologized. "It was worth it," he shrugged.

You finished setting up your laptop. "Are we really starting this now," he asked chuckling. "I watched You're Lie in April. You promised you'd watch Demon Slayer," you insisted. He sighed, "I did didn't I?"

An excited smile tugged at your face as you started the show, your laptop resting on your chest so the screen would be right in front of you both. You smiled as you hit play. "O-okay starting off intense from the very beginning," he noted. He shifted curling up to your side to see better.

You looked back to the screen your mind and heart ran rampant. It was the first time you were fully on your own, with the people you chose, in a house that felt like home. You were the one free to make your own decisions and that freedom sent a terrifying electricity through your veins. For the night, you were unstoppable, invincible. Life was wonderful and beautiful and so much brighter than the seventeen years prior.

~~~~~
~Terushima~

He looked over. Her head had softly rested on his and sure enough, five episodes in, she was asleep. He smiled at the soft half-smile on her face. Her hands curled up on the laptop as she took steady slow breaths. He smiled to himself. Even after all of the bullshit of dumb things he had done up until this point, every possible thing he had worried over, she still accepted him for who he was.

Putting together the manager mishap and her trusting nature he could understand why her brother was the way he was. He didn't like it, nor was he going to accept it though. She was bad at standing up for herself and protecting her was never going to fix that problem. But if anything hurt this pure Hufflepuff ass bitch, he was certainly going to throw hands.

He slid the laptop slowly and she snapped awake looking worried and startled. "Sorry, I was trying not to wake you," he apologized. "I fell asleep," she asked. "Until you jumped up just now, yeah," he replied. "Sorry, habit," she muttered. That comment didn't sit well in his stomach. To be such a light sleeper and so sensitive to movement was usually tied to a lot of not nice things.

"Bad mood."

The tone had been hushed and urgent. Sure her brother was overprotective but he couldn't help but worry where that stemmed from. They were in their own home. Who was in a bad mood? Why did he sound so worried? Why did she grow just as urgently panicked?

She didn't stray away from many topics, but getting her to talk about herself was like pulling teeth. He'd read, witnessed, and studied enough to have a good thirty, worrisome, possibilities running through his mind.

"Night Yuuji," she mumbled in a small voice. "Night sunshine," he replied softly as she hugged her pillow. Before she fully drifted off he wrapped an arm around her side to keep from startling her later.

She tensed and his brain woke up more. He's coming off too strong again. Isn't he? He went to pull his arm back but her hand gripped onto his arm keeping it in place.

She startles really easy doesn't she?

He relaxed again and settled into the pillow he'd be using for the night. What was Koushi protecting her from? The question nagged at him again like the night before. He had played it off like a joke earlier, but he was really worried when she didn't call or text him back after that shady exit.

He was really glad it worked out for him to be able to physically see her. He was also really glad Futumata cancelled on him and yelled at him to try and figure out some way to see or talk to her. In all honesty, his intention was to invite her over instead if she was comfortable with it.

Why does his mind never stop?

He just wants to go to fucking sleep.

How long has he even been spiralling?

He watched as she shifted and rolled over. "You think loud," she giggled sleepily. His heart melted at the sound. "Sorry," He mumbled. He looked down as she wrapped her arms around his neck. Heat rose to his cheeks as she started to stroke his hair.

He wanted to hold her close, to kiss her, and learn everything there is to know about her. He felt like he was stumbling blindly as they bounced through drastic swings of very flirty and practically acting like a couple, to incredibly platonic. He liked her so god damn much but it didn't mean shit because you need two people for a relationship.

How do you make someone fall in love with you?

"Yuuji," she mumbled tired as her hand rested on his face. He opened his eyes, which he hadn't realized he had closed. Did she just call him by his first name? Again?

Her patient kind smile was waiting for him when he opened his eyes. He felt guilty for keeping her awake when she seemed so tired. How does one think loudly though? "You fidget when your brain gets all zoomy," she shared in her tired sleepy voice.

She was so cute.

"S-sorry," he apologized still flustered by the small, gentle hand that was so tenderly caressing his cheek, "It takes a while for my brain to unwind. I can sleep on the couch or the chair in here if I'm keeping you up." "No, it's okay. I've been a little hypervigilant the last few days. I usually stay out and sleep like the dead when there's another person with me," she explained, "Talk about it."

He looked at her confused, "Talk about what?" "Everything, nothing, somewhere in between. Surprise me," she mumbled, "Also, your cheeks are very warm." "You know how some people can blush softly," he asked. "Mhmm," she hummed in the dark and dim lighting.

The only glow coming from the moon out her window had cast them in cool dark blues where they could see each other yet shadows hid the colors they had been enveloped in earlier.

"Okay, well, I can't do that," he shared. He watched the tired smile spread across her face. "I blush very loudly. Like Tamaki giving Haruhi the cover ups, kind of loudly," he shared. "Why are you blushing," she giggled. "The human embodiment of sunshine and joy is caressing my cheek," he shared. "You're sweet," she mumbled before burying her head in his chest which prompted the heat to flood to his cheeks once more. "How'd you get into volleyball," she asked, sounding muffled.

Somehow this tired angel had prompted a lengthy story which did result in both actually falling asleep.

~~~~~

"Yuuji," a voice shouted. He groaned hugging the heat source in his arms tighter as he tried to bury his face. A round of laughter filled the room and he cracked an eye open. (Y/n)'s blinding smile greeted him. If he had to wake up, this wasn't a bad way to do so. "It's almost eleven we have to get going," she reasoned. He just shook his head and buried his face into the red fabric of her sweater.

He felt a sharp jab to his side and yelped as he jumped up. (Y/n) laughed as she scrambled up with a pillow in hand now. It was the pillow he had been using. "You brat," he complained, laughing himself. He tried to roll back to sleep when he was assaulted by a flurry of hits from a surprisingly dense pillow.

He turned and caught a hit before pulling the pillow toward his chest. (Y/n) gripped on and toppled onto the bed on top of him. He pulled the pillow off of his face and stared up like a deer in headlights as she was braced on top of him. Butterflies fluttered from his pounding heart up through his chest and face as heat followed. Almost as if he had downed a shot of sake. Her look of shock traded for a soft smile and his heart stopped as it melted.

Damn he had it bad.

"Come on I need to turn this place into a hufflepuff common room," she insisted. "Wait seriously! Are you a hufflepuff," he asked proud to have guessed correctly. "What, could you not tell by the everything about me," she asked laughing as she rolled over, flopping onto her back. "Hey hey, I was just proud to have guessed accurately, sunshine," he defended.

~~~~~
~Your POV~

You smiled to yourself as Yuuji and 'Kaash debated over theoretical physics that could make time travel possible and the ramifications of that.

Bokuto looked between you and Meiko, his hair was drooping as steam poured from his ears as he failed at following along their conversation at all. "Hey, Bokuto-san what do you think would look better in the hanging planters I got. I'm between the english ivy, string of pearls, and marble pothos," you shared pointing to each of them.

He perked up before looking between each of them. "Thank you," Mei mouthed. You nodded smiling. "Ooooh I really like these two. This one kind of scares me," Bokuto shared. You laughed asking, "String of pearls scare you?" "They're all lumpy and weird," he defended. "Then they're definitely out," you declared.

"I think this one. It feels more happy than this one," Bokuto concluded. "Marble pothos it is," you declared. "Can we name it," Bokuto asked excited. You laughed and nodded, "Absolutely! Since you helped me pick this one you can name it." "Really," he asked excited. Bokuto was now bouncing on the balls of his feet. "Yeah," you nodded smiling back.

"Can I get back to you on the name," Bokuto asked making his serious thinking face. You nodded trying to bite back the full force of your smile at how serious he was taking this and how excited he was.

"Okay so we got the rug, the bedding, the desk chair and desk, fabric, upholstery, blankets, plant, wood stain, and a lot of wood," Mei listed off. "And I have the drill, and drill bits at the apartment. And the nail gun I smuggled from the props weekend. Ooh. Screws and nails. I need to get nails, screws, washers and nuts to be safe," you thought aloud.

"Didn't know you were so handy, Sunshine," Yuuji said beside you. You jumped before laughing as he managed to sneak up on you. "Props and costuming since I can remember," you shared. "Don't let the modesty fool you, she's incredibly talented," Meiko insisted. "I wouldn't say incredibly," you countered as she pulled up her phone. "I have pictures saved of some her best pieces," Mei insisted, showing Yuuji like the proud mom-friend she was.

"How are you going to cut the wood when we get back," Akaashi inquired. "I took the measurements before. That's why I asked for the specific pieces. And whatever is left over is going to go into making the sectional thing next weekend," you shared.

"And the wood and desk set are going to be delivered around three right," Akaashi asked. You nodded to confirm. "So then we should wrap up here if you want to stop in the dollar store because Kou is going to get distracted," Akaashi shared. "He might still be thinking up a plant name, but I'm good to head over after we grab some screws and nails," you shared. "Sounds good," Akaashi nodded.

"Dude you made all of these," Yuuji asked. "Maybe," you replied. "So cool! Dude," he exclaimed looking back and forth from the phone to you. You laughed nervously before he shook your shoulders excitedly. "Who needs instructions!? You're like a prop and clothing pro! That's so cool," he exclaimed. You laughed but it was brought to an abrupt halt as Yuuji froze.

You turned to see Enno with his girlfriend. "Every fucking time," you mumbled trying to stay calm. "This is awkward," Chikara strained. The ball to Yuuji's tongue piercing was poking out meaning he was, quite literally, biting his tongue.

An icy pit formed in your stomach. "H-hi Meiko-san and (Y/n)," Kana greeted timidly. "Ito-chan. Do you mind if we have a word with your boyfriend," Meiko asked wearing her faux polite smile. "Please don't murder him," she pleaded. "Kana," he exclaimed, betrayed. "Do you not remember when Noya pissed her off and he went missing for three days," she reminded.

"Mei, please relax. It's fine," you pleaded. You motioned for her to stay. "I promise not to murder him. Sorry to bother you Kana," you said politely before nodding for Enno to follow you. You avoided the rest of their eyes as you braced yourself to face the consequences for trying speed up living your own life.

"What is he doing in Tokyo," Enno asked. "Helping me set up in Akaashi's apartment so it's ready to move into when Koushi graduates. He okayed me moving. He does not know Terushima and I met again at Akaashi's Halloween party," you shared, "Which is also why he isn't questioning you about Kana, or you pretending to be my boyfriend to scare him off."

Enno's face paled. He was as white as a sheet. "Yeah, when I saw him and struck up a conversation he was asking where you where. He didn't want to risk giving off the wrong idea, especially after having been confronted by you and Koushi just a few days prior," you shared.

He avoided your gaze unable to confront you. "Chikara," you asked trying to hold back the hurt in your voice, "Please don't tell Koushi." "(Y/n), he's an asshole," Enno warned. "He's really not. Even if he was why can't you all just let me figure out for myself. It's not even like we're dating, Chikara," you stressed. "Have you told him that," Enno asked glancing up.

Your patience snapped. "Are you going to tell Koushi," you asked, pulling up the walls. A numb feeling washed over the ache in your heart. Enno looked back at you petrified by your expression.

He sighed in defeat, "No." You nodded mostly to yourself. "But we're going to talk about this later. Otherwise I will tell your brother," he warned. You tried to keep from rolling your eyes. "We're just trying t-," Enno started. "Save it," you cut off, "Please. I don't- if I- Just don't."

"(Y/n)," he softened. "I'm really tired and... I just want to finish getting stuff for my room. I really don't feel like fighting with a friend right now," you strained. He clenched his jaw before asking,

"Is he going back with you?" "Yeah. I'm not going to fuck him if that's what you're asking," you remarked bluntly. "That's not-," he started with a grimace. "It's not? So what? I'm just not allowed to-," you started and bit your tongue, "No I'm not- I'm not arguing this now. Yes, he is coming back to the apartment. So are Mei, Bo, and Akaashi. In case you decide to change your mind and report back to Koushi."

You felt eyes burning into the back of your head. "I have to go. Or I'm going to be late to pick up my desk," you said before going to turn. "(Y/n), please," Enno started. "What? Please what? I thought you were my friend too," you countered turning back to him. "Of course I'm your friend," he insisted. "Friends don't try to control friends," you strained taking a breath to maintain your composure, "Hope you have a good rest of the day."

You walked back to the group without stopping to see Enno's reaction. You knew it would crack the thin walls meant to protect you from the barriers you failed to create in the first place.

~Meanwhile: Terushima~

He couldn't catch much, as Ito tried her best to hold a pleasant conversation. He just knew he saw that Ennoshita guy go pale, get shocked, and jump between worried and mad. It definitely could pass for a fight between exes if he didn't know better.

Did he know better?

Of course he did. Why would she lie about that?

Guilt settled in his stomach for even considering that. The only person of the group who seemed unaffected by everything going on was Bokuto who seemed to be staring thoughtfully at the marble pothos.

"You came all the way to Tokyo to see (Y/n)," Ito asked dragging his attention away from making sure Sunshine was really okay. He scratched the back of his neck nodding. "It's just a couple minutes by train I used to take a longer walk to see my friends in junior high," he shrugged off. "Most people wouldn't put forth the effort. You must care about her a lot," Ito pointed out.

More than you can fucking imagine, but your boyfriend is kind of a prick about this whole situation and he's trying to make this as stress free for her as possible but somehow all of the Karasuno kids keep showing up at the WORST god damn times.

Could he say ANY of this? NO! But fuck, he wished he could.

"It was really nothing. I was bored and she seemed kind of off the day before so I wanted to check in on her one way or another," he said glancing back over. He caught Enno saying something like "of course I'm your friend" when Ito seemed to continue her never ending stream of conversation which must be wonderful in any other circumstance.

"Yeah the guys are all super protective of her," she said warmly. "Noticed," Terushima strained.

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