SUMMARY: Middle school is going well for our boys so far. That is until someone decides to ruin it.

THE GREEN-EYED MONSTER

Izuku wanted to say he can take of himself because he's not a scrawny kid anymore. He's been training to become stronger for months now, even learned some awesome moves from Kacchan. But he had one weakness when facing bullies, he lacks the conviction to stand up to them with physical violence. Katsuki's voice echoed loudly in his head, stand up for yourself! Fight back, shitty nerd! Don't let these losers beat you up!

He dodged a fist aimed for his face. He turned to the bully and raised his hands in surrender, "C-Can we not resort to physical violence?"

"Shut you mouth and fight back you quirkless loser!" said the other boy. He's round and short, and he has a pair of wings on his back. His companion, a tall lanky kid with long stretchy fingers, tried to take a hit and Izuku danced away.

"C'mon guys! L-let's talk this over!"

"Talking's what got you into this, what makes ya think it'll get you our huh?"

"A shitty quirkless kid like you don't belong here!"

Honestly, Izuku should be immune to such insult but he's not. They still stung and he gritted his teeth, don't let their words get to you. He dodged their attacks again, and he's actually quite impressed with himself. Maybe these goons weren't quite as coordinated as him. He could escape. He just needed an opening.

"Why is Bakugou even friends with someone like you?"

"Yeah, you're only going to hold him back! He can't be a great hero if he has to watch over your back all the time!"

Izuku faltered, his thoughts betraying him. Maybe they're right. In his distraction, the skinny guy hit him in the face and he fell on his butt. They laughed at him as he sat on the ground, holding his cheek.

"Hey, leave him alone," said a voice. The bullies turned around to see a third-year student approaching. They sneered at him, "Another quirkless loser. Hey Midoriya, why don't you be best pals with him instead?"

"Yeah! You losers should stick together!" said the winged boy with a snigger.

Sasayaki narrowed his eyes and whispered, "I have informed a teacher. So, why don't you turn around and skedaddle?"

The bullies cursed under their breath and quickly made their escape, "Watch your back losers!"

The third-year sighed as he approached Izuku. He offered a hand which the younger boy took and pulled him up to his feet. Izuku smiled sheepishly at the older boy, "Thank, Sasayaki-senpai."

"You need to be careful. A lot of the students here don't take kindly to quirkless people like us. Even teachers. They'll turn a blind eye to you."

"But you said you told a teacher?"

"I lied."

"Oh."

They fell in an awkward silence. Izuku moved to pick up his yellow backpack. It's covered in dust and he patted at it. He turned to the senior student, "Uhmm, I guess I'll be going now."

"Where's Bakugou?"

Izuku paused, "Uh, Kacchan's got extra-curricular class outside of school."

"I see."

"Do you need to see him? I can text him and tell him that you-"

"No, it's alright. I'll talk to him when I see him."

The younger of the two nodded his head and walked away. Sasayaki's eyes followed him calculatingly until he disappeared outside the gates. He stuffed his hands in his pockets and went on his way, no luck again, huh?

Katsuki wiped the sweat of his chin with the back of his hand. He stared at the stacks of five crates and made some mental calculations. He inhaled deeply and ran towards it. He swung both his arms behind him and a pair of explosions from his palms propelled him upwards and over the crates. He landed in a roll on the other side and stopped on his back, gasping for air. A grin split his face and he threw his arms up in victory, "YES!"

"Well done. Now you need to work on your landing," said Kitamura with a proud smile.

Katsuki raised a thumbs up before his arm flopped down. He lay on his back and stared at the ceiling as he tried to catch his breath. Kitamura appeared over his head and dropped a towel over his face. He sat up to wipe the sweat off and thanked the man when he offered him a bottle of water. AS usual, after taking a few gulps he poured the remaining water over his head. He shook his head and send water droplets spraying. Kitamura chuckled and he heard the mains something about him acting like a dog.

"Hah?!"

The man smirked in amusement, "Nothing. So, you up to try go over the next obstacle?"

"Heck yeah, I am!"

"Keep in mind not to overuse your quirk."

"Yeah, yeah, I know the drill," said Katsuki as he got to his feet. He shook his arms at his side and flexed his fingers, "I'm still good to go."

Kitamura nodded and took the bottle and towel from him. He stood aside to observe the boy as he attempted to go over a stack of seven crates. He watched him took off in a starting run before his hands sparked and let out an explosion. But it's weaker than before. He started running as he heard the boy curse and brought his arms forward to shield his face before hitting the crates head on. There was a loud crash as the crates toppled over, "Bakugou!"

Katsuki got up from under a pile of splintered woods, "I'm fine!"

He brushed off some of the debris off him and picked out woodchips from his hair. Kitamura's eyes scanned the boy and let out a relieved sigh, "I think that's enough for today."

"No. I can still-"

"You've reached your limit."

Katsuki looked away with a pout. He finally realized the tremors in his hands and he clenched his fists, "Okay."

"I'll call your father. Go get cleaned up," said the agent as he motioned at the door. The boy sighed as he headed for the exit, grumbling to himself. Kitamura took out his phone and called Masaru to come get him. He hung up and pocketed his phone. He took out his tablet from inside his coat and typed in new data from the day's exercise.

Katsuki was progressing well. He can make bigger controlled explosions and now they moved on to exercises where he tries to control short bursts for a short push while he's in midair. It was the boys' idea. He suddenly spoke up about wanting to use his explosion to fly. He said he got an idea after watching one of Endeavor's battles on record.

"I don't know if I can do it but I wanna try and use my explosion to propel myself in the air. You know? Like rocket thrusters. Might come in handy if I'm going to chase a bad guy."

Kitamura had agreed to watch over him and help out on this little experiment, and it looked like the kid can do it after all. Just needs more practice and get the landing right. He typed on his tablet what kind of new obstacles he should set up to challenge the boy. He went through Katsuki's data and made some updates. He noticed that the boy no longer has any appointment set up with Mishima. He wasn't aware of that.

He exited the room and took out his phone again. He called the therapist, "Mishima, I noticed Katsuki doesn't have any scheduled appointment with you. Why is that?"

"Oh, he's actually getting better. Though I would like him to come for at least a couple more sessions but the boy insisted he's feeling better. His nightmares had stopped for a while too and his anxiety doesn't get to him as bad as before. His tests are positive."

"I see. That's good news."

"I made him promise to come see me as soon as he starts to have problems."

Kitamura smiled, "I'm not sure he'll do that."

"Oh, he will. I've talked with both of his parents and made it explicit that he needs to come see me if something happens."

"Well, thank you for your hard work. I'll keep an eye on the boy as well."

He ended the call and held his phone in his hand, staring at it for a few moments in thought before pocketing it. He sighed and headed for his office. He needed to get some paperwork done before he goes home.

Katsuki jolted awake when his father shook his shoulder. He pulled out the earbuds blaring in his ear and turned to him, "What?"

"We're stopping by to buy some groceries. Do you want to wait in the car?"

The boy thought about it and then shook his head, "Nah, I'm coming along."

"Alright."

Masaru drove the car down into a basement parking and luckily found an empty spot soon after. He parked the car and both he and his son got out. He watched his boy stretched his arms over his head and scratched his head, "What're we getting?"

Masaru showed him a list scrawled with his mother's neat handwriting. He memorized the list and nodded, "Alright. I'll get the dry food and meet you at the fresh produce?"

"Sounds like a plan," said his father with a wide smile.

They entered the supermarket and took their separate ways. Katsuki grabbed a basket by the entrance and stalked toward the aisle where he remembered they have the rice and spices. He was looking at the shelf when he felt a presence behind him. He turned around and raised his brows nonplussed, "Oh, it's you."

Sasayaki smiled at him, "Hello, Bakugou-kun. It's been a long time since we met. Are you shopping for groceries too?"

"Uhh, yeah."

The senior student nodded as he picked up a pack of rice, "How are you doing?"

"I'm fine."

"Midoriya-kun mentioned you were busy with extra-curricular activities outside of school. May I know what it is?"

Katsuki was hit a sudden wave of dizziness and he grabbed his head, "I, uh, I was training."

He blinked. Huh? What am I saying?

"Training? Oh, you must be aiming for UA! I wanna go there too but then you know, I'm quirkless and all. Quirkless people can't go to UA, right?"

Katsuki blinked slowly, "Deku's aiming for UA too."

Sasayaki tilted his head curiously, "Really, now? What's a quirkless kid like him doing, aiming for UA?"

Katsuki could feel tingling on his fingertips, he looked down at his hand, "He wants to be a hero. Deku said he'll try for Gen Ed or the Hero Support Course."

"I see. Say, how close are you two?"

"We're… we're pretty close. I think."

"You sound unsure of yourself, Bakugou-kun. Is it possible that you find him holding you back from being your best?"

Katsuki frowned at the ringing in his ears, "Deku's not… he's… not… he's holding me back?"

"Well, you had to run around and save him every time he gets in trouble, right? Must be tiresome. I'm surprised you haven't ditch him. A weakling like him doesn't deserve you."

"Wait. What're you… what're you saying?" asked Katsuki as he pressed a hand against his temple. Sasayaki was staring at him with cold eyes. The blond blinked his eyes when his vision got fuzzy, what's going on?

"Why don't you just ditch the loser? You called him Deku for a reason, right?"

Katsuki gasped at a stab of pain in his head. His internal alarm bells were ringing, telling him something's wrong but he could grasp onto it, "I-it was because I read the kanji wrong!"

"Why would you deny yourself freedom, Bakugou-kun? He's holding you back."

"SHUT UP!"

Sasayaki took a startled step back. He sighed and swept his hair aside, "I'll see you around, Bakugou-kun. Why don't you forget this meeting, alright?"

The older teenager watched as Katsuki's eyes glazed over. Sasayaki grinned evilly as he walked away, "Torment Midoriya-kun for me, won't ya? Get rid of him."

Masaru got worried when he didn't see his son for a while so he hurried toward the dry food aisle. He saw his son standing alone, all spaced out, "Katsuki!"

His son blinked slowly, "Huh? Dad?"

"Katsuki what's wrong?" asked Masaru as he put a hand on his shoulder, squeezing gently.

His son blinked again, slowly. Masaru noticed how flush he looked. He put a hand to his son's forehead and cheek, "You're warmer than usual. Are you feeling well?"

"I uhh… I don't…" the boy frowned, "What am I doing here, dad?"

Masaru frowned with worry. His son was fine a few minutes ago. Maybe he missed something? He grabbed the boy by his elbow and led him toward the counter, "C'mon, we're going home."

"Mhmm, okay."

Masaru sent a quick text to his wife to prepare the things needed if their son truly came down with something. It's been a while since he got sick and Masaru remember well how it's often an uncomfortable ordeal for his son, because of his quirk. He gently pushed his son into the passenger seat and buckled him in. His worry spiking at how complacent the boy is. He loaded the care with the groceries then hurried to the driver seat. He blasts the AC to keep his son cool and the drove out of the parking, "Hang in there, son. We'll be home in a few minutes."

When the reached home, Mitsuki was waiting. She rushed forward to take her son from her husband, "C'mon, brat. Let's cool you down."

Katsuki nodded mutely and Mitsuki shot her husband a worried glance. She cursed under her breath and led the boy up to the bathroom where she had filled the tap with tepid water. She peeled off his sweat soaked t-shirt and his pants, leaving him in his boxers. She frowned at his flushed skin, "Let's get you cooled down, okay?"

She gently led him toward the filled tub and maneuvered him so he had his back resting against the cool wall of the tub. She scooped some water with a pail and poured it over his head. She repeated the action three times and her worry was beginning to inch towards panic when her son remained quiet. She turned on the tap to fill it with cold water.

Mitsuki looked over her shoulder when she heard footsteps, "Masaru!"

Her husband appeared holding a thermometer, "What's wrong, Mitsuki?"

"He's... he's so quiet. I don't know what's wrong."

"He was fine when I picked him up and when we reached the store."

Mitsuki worried her bottom lip, "You think he got hit by a quirk?"

"I don't know. But let's get his temperature down. One step at a time."

They ended up having to give him an ice bath to finally get his temperature below 38 degrees Celsius. Masaru had to rush to a nearby store to buy ice for that. They dressed up their son and lay him down on his bed. Throughout the event, Katsuki remained silent and unresponsive. He now lay sleeping with a cool rag on his forehead. His parents decided to wait until morning before making any calls. Masaru volunteered to watch over the boy all night.

Morning came and Katsuki groaned as he grabbed at the rag on his forehead. He squinted at it confusedly. He struggled to sit up, everything was fuzzy from yesterday. What the hell happened?

He glanced to his bedside and blinked at the sight of his father dozing on a chair. He grimaced, old man's gonna ruin his back. He threw the rag in his hand and it hit his father's face. He grinned slightly when his father snorted as he woke up in surprise. His father stared at him, "Katsuki. You're awake!"

"What happened?" he asked hoarsely.

"You had a sudden high fever last night. Did you remember?"

Katsuki frowned and shook his head. Masaru sighed and pressed the back of his hand against his son's forehead, "Well, you don't seem to have a fever right now. How are you feeling?"

"Like crap."

Masaru's brows hitched toward his hairline. His son rarely admits it when he feels horrible. He grabbed the bottle of water on the bedside table and handed it to his son, "Here. You better drink some water."

"Thanks," rasped his son as he took the bottle.

There was a knock and Mitsuki opened the door, "Oh, good. He's awake! How is he?"

"I'm right here and I'm fine," said Katsuki.

"Well he seems to be back to normal," said Masaru.

Mitsuki sighed, "Yeah? But let's keep him here for today. Just to be sure."

"I ain't skipping school!"

"Shut it brat, it's for your own good! You were pretty out of it yesterday."

"Your mother's right, Katsuki. You had us worried. Stay home, alright? Just for today."

"Fine," said the boy as he rolled his eyes.

Mitsuki sighed, "I'll call the school. You better text Izuku-kun so he doesn't wait for you."

Katsuki accepted his phone as his father handed it over. He unlocked the phone wrote and opened the chat app. He frowned when he felt unreasonable anger at the sight of Izuku's nickname on his phone. Masaru noticed, "What's wrong?"

Katsuki shook his head, "I dunno. I just felt… nevermind."

LordExplosionMurder: Oi, shitty nerd. Don't wait up for me. I'm stuck at home right now.

It didn't take long for the three dots to appear.

Deku: What's wrong, Kacchan?

He was hit with a strong sense of anger at the sight of his childhood nickname. He bit his tongue, What's wrong with him?! He took in a deep breath and exhaled slowly, like how Mishima had taught him.

LordExplosionMurder: Got fever.

LordExplosionMurder: And stop calling me that stupid name.

Deku: ?

Deku: You mean "Kacchan"?

LordExplosionMurder: Yeah. It's dumb and childish.

Deku: …ok.

Deku: I'll bring your homework over later.

Deku: I hope you feel better soon.

Katsuki closed the app and put his phone on his lap. He didn't realize his father had left him alone in the room. He frowned in thought, what was that? Why did I feel so angry at Deku? He shook his head, maybe he's just grumpier than normal today. Yeah, that's it.

Katsuki looked up from the homework he was doing when there was a knock, "Yeah?"

"Kacchan, it's me," replied Izuku's voice.

Katsuki gripped at his pencil hard until it snapped. He hissed in annoyance as he threw it in the bin, "Hold up!"

He walked to the door, his heart beating rapidly and blood rushing to his ear. Why? Why am I feeling like this? What's going on? He thought in confusion as he held onto the doorknob. He did the breathing exercise again. He gulped and tugged the door open.

Izuku smiled brightly at him, "I got your homework! I'll help explain what you-"

"Get. Out."

Izuku frowned at the ground-out words, "Kacchan?"

"I told you… to stop calling me that."

Izuku took a step back, fear creeping into him as Katsuki glared at him fiercely. Those eyes were never aimed for him. Always the bullies or someone the blond would see as a threat, an enemy. The blond boy's body was trembling as if he was trying to restrain himself, "Kaccha-"

Izuku slammed against the wall as an explosion erupted between them. Izuku coughed at the smoke he inhaled. He looked up at his friend fearfully but what he saw stabbed at his heart. Katsuki was staring at him with wide disbelieving eyes. His red eyes moved to stare at his trembling, outstretched hand in horror. Izuku got up to his feet, "Kacchan."

"Stay back, I-Izuku!"

"Look, I'm okay! Don't worry about me."

Katsuki shook his head, his hands rising to grip his hair tightly as he retreated into his room, "But I… I don't know why I… I didn't mean to blast you."

Izuku's head snapped to the stairs when he heard hurried footsteps, "Katsuki?! Izuku?!"

"We're fine! It's an accident."

"It wasn't."

Izuku turned to Katsuki who was sitting on the floor with his knees drawn to his chest, his back pressed against the bed. Izuku approached the room but stopped when Katsuki's fearful eye met his, "Don't. Stay back!"

"What's going on here?" asked Masaru. His eyes widening at the soot on Izuku's face.

"It was an accident. Kacchan, didn't mean to do it!"

"Katsuki?" asked his mother bewildered. Her son used his quirk against his best friend?

The boy stared at them with wide eyes, "I don't know why…. But seeing you," he paused as he stared at Izuku, "I feel so angry. I want to hurt you so bad right now, Deku."

Mitsuki rushed into the room, "Katsuki, what's wrong with you?!"

Tears streamed down Katsuki's cheeks, "Get out of my sight before I hurt you for real. P-please."

Masaru led Izuku downstairs to look him over. He let the boy sit on the couch. The man wet a rag and returned to wipe the soot off the boy's face, "Tell me what happened."

"I was talking about his homework but he got angry for some reason. I called his name and he suddenly…. He suddenly used his quirk on me. He's never done that before."

Masaru frowned, "As we have feared."

"What is it? What's wrong with him?"

"We think he might be hit with a quirk yesterday evening. I'm going to make a phone call."

"Could it be an emotion-related quirk? Or mind manipulation?" asked Izuku, his mind racing with random quirk facts he knew. He looked up as Mitsuki descended the stairs. She rushed toward him, her face worried, "Are you alright, Izuku-kun?"

"Y-yeah."

"I'm really sorry for what he did."

Izuku shook his head, "It's an accident. Your husband thinks Kacchan might have been hit with a quirk."

"I'm afraid of that. It could be any quirk and we won't know how long it'll last."

Masaru returned, "Dr Shiozaki wants us to bring him over."

Mitsuki nodded and went back upstairs to get their son. Masaru turned his attention to Izuku, "I'm sorry Izuku-kun. But since it seems you're the trigger, I think it's best you go home now."

"O-okay. Can you text me about his condition later?"

"I will."

Izuku grabbed his backpack and left the house. He gripped the straps tightly in his grasp and his brain began to make theories and connections. So far they know Katsuki couldn't control his anger when he is nearby. So, the one who hit him with the quirk must have something against them. But who? They kind of made a few enemies over the years. None of them have any mind manipulating quirk. But there was someone who was always asking about Katsuki's whereabouts. A voice echoed in the back of his mind. Words said many months ago.

I'm kinda jealous of you now, Midoriya-kun.

Izuku frowned, no that's impossible. Sasayaki said he's quirkless. Maybe he had someone who helped him? But he didn't seem to have any friends. The third year student was always seen alone in the school. Izuku's eyes widened when a thought popped up, but what if he's not quirkless? He clenched his fists. He'll confront him tomorrow!

Izuku found Sasayaki at the library the next day. He approached the third-year student, "Sasayaki-senpai, can we talk, in private?"

The older boy closed his book with a sigh, "What it is?"

"I need to ask you something."

"Can't we talk here?"

Izuku shook his head. Sasayaki rolled his eyes and stood up, "Alright. Let's talk in the literature club room."

Izuku followed him cautiously. They reached the club room which was situated in one of the quietest blocks in the school. Izuku closed the door behind him. He chose to block the entrance and exit. The senior student crossed his arms over his chest as he stood by the window, "What do you want to ask?"

"Did you do something to Kacchan?"

Sasayaki raised a brow but Izuku could see the slight twitch at the corner of his lips, "What makes you think that?"

"You've been asking me about him, regularly. Something happened to him two days ago and I have a feeling you're involved," said Izuku as his brows knitted together.

The third-year student sighed, he looked to the side and rubbed his neck, "Care to share your thoughts?"

"You're not quirkless, you did something to Kacchan with your quirk," said Izuku firmly.

Sasayaki's eyes glanced to meet his, "You have no proof."

"It's true, I don't. But I have a hunch."

The blue-haired teenager guffawed, "Hahahah, you're relying on your hunch? Tell me, what do you think I've done to dear little Bakugou?"

"You… you manipulated him. I'm not sure if it's his thought or emotions, and I became the trigger to his outburst."

Sasayaki's eyes widened in mock surprise, "What did he do?"

Izuku bit the inside of his lip and glared at him. Sasayaki smirked, "Oh, did he hurt you? How? Verbally? Physically? How did he react?"

"You're not denying you have a quirk."

"And I'm not saying I have one."

"I know you have one! Make it stop! Whatever you do to Kacchan, make it stop!"

Sasayaki hummed as he brought a hand up to cup one cheek, "No."

Izuku stepped forward, "Why are you doing this?!"

The older boy's eyes narrowed, "Why? Because life's not fair! I hate that you get to have a friend who watches your back! Me?! I have no one! No one wants the quirkless loser!"

"But you're NOT quirkless! Why are you even pretending to be one? Why are you hiding it?!"

Sasayaki's hands slammed on the table and he shouted, "Because it's a VILLAINOUS quirk!"

Izuku froze as he stared at the glowering teenager. Sasayaki was breathing heavily, "I was shunned by everyone because of this accursed quirk! My parents even abandoned me! Too scared their little Hibiki would turn on them! So, I decided to be quirkless! At least people don't fear me this way!"

Izuku clenched his fists, "But you use it for bad things."

"So what? It's my quirk! I'll use it for my own advantage!"

"If you keep using it like that, you're becoming the thing you hate about it! Your actions ARE villainous!"

"WHY DON'T YOU SHUT YOU MOUTH, MIDORIYA-KUN?!"

Izuku's mouth involuntary snapped shut and his eyes widened in shock. Sasayaki grinned dangerously as he approached. Izuku tried to move away but he froze when he heard the teen say, "Stay still won't ya? Good boy."

Sasayaki stopped in front of him, chin tilted up and eyes glaring down, "You see, this quirk has a few pros and cons. Why don't you have a seat?"

Izuku sat on a chair, his body moving on its own. He glared at the third-year student. Sasayaki leaned against the door, "You're a bright boy, I'm sure you've figured out how this quirk of mine works. It's really bothersome that I have to deliver my commands as a question or else it doesn't work. Would you like to talk?"

"What are you going to do to Kacchan? What do you want with him?"

"I don't want anything from him. I just want to destroy what you two have: trust. So, listen well Midoriya-kun," said Sasayaki as he leaned closer, his eyes glinting mischievously, "Why don't you tell him how you feel? Tell him the truth. All of it. Let him know all the little details that you hate and fear about him, can you do that, Midoriya-kun?"

Izuku tried, he really did. But without control over his hands, he couldn't cover his ears in hopes to protect himself from the teenager's quirk. He was a fool for coming unprepared even though he guessed the teenager's quirk correctly. He could hear a ringing in his ears as his thoughts began to mesh together in a confusing conundrum. The command being planted into his brain and its roots growing deep, consuming his consciousness. His last conscious thought was an apology.

I'm sorry, Kacchan!

A/N: Dun, dun, DUNNNNN! You know it! Sasayaki's bad news! He's a jealous prick. Oh, dear. How will this ruin Izuku and Katsuki's friendship? Will they be able to stop what Sasayaki's plan?

OC Profile UPDATE

Name: Sasayaki Hibiki (The name Sasayaki means 'whisper' and Hibiki means 'sound, echo')
Quirk: Persuade
Quirk Description: Sasayaki's quirk is a mental manipulative quirk. To activate it, he needs to have intent and call the name of his target at least once to gain their attention. The downside of this quirk is that he can only deliver his orders in a questioning sentence. It's also less effective on someone who has a very strong mental fortitude. Sometimes his quirk can make his target experience high fever especially when they're subconsciously trying to cancel his orders. The effects usually wear off between 24 to 36 hours.
Character Description: Sasayaki is a senior student at Izuku and Katsuki's middle school. He has a thin body and has a short stature for someone his age. He has dark blue hair with long bangs that tend to cover his grey eyes. He appears to be stoic and unsociable as he doesn't have many friends and gets bullied often for being quirkless. He shows great disdain at the friendship Izuku and Katsuki shared as he never experience such a thing. He has a strong need to destroy other's happiness, especially ones he couldn't have himself.