Chapter 1
A young Izuku was crushed in a hug by Aunt Mitsuki, the tears still fresh on his face. She did her best to comfort the distraught child, but to little success. Uncle Masaru showed up not too much later after picking up Katsuki from school. A jarring stop to the first day. They too joined the hug, a rare moment of emotion for the young boy. Perhaps one of the first (his parents had been racking their brains to try and think of a moment before this, nothing came to mind) moments of sympathy from him, as he too, somehow knew the long lasting effects this would have on the remainder of Izuku's life.
Neither he, nor anyone who enjoyed living, would admit it, but the aggressive spiky blond has a soft spot for the green haired boy. Izuku slowly managed to compose himself but continued to cling to the Bakugos.
After a solid 5 minutes, they separated and the distraught stricken Izuku is in a daze, running on autopilot. Aunt Mitsuki gently carries him into the car, before going to our green haired boy's now empty household. He mindlessly took his notebooks, a number of clothes, and a small photo album before taking the keys, and locking the door behind him.
The sombre crew went to the Bakugos' household, and while Mitsuki made dinner, Masaru and Katsuki set Izuku up with his room. Formerly the guest room, it now belonged to the new member of the Bakugo household. He quietly put his bags down, before curling up on the bed. It was getting dark, and he had not eaten anything since breakfast, but he felt no hunger.
Ah breakfast. A simple time that was, Izuku, together with his family. The family was going through their normal morning routine, involving various cereals, conversations, and unconditional love. Before long they had entered the car, and his parents bid him farewell as they dropped him off for his first day of school. He knew it would be his most exciting day for a long time to come, the next one hopefully being when he got his quirk. How naïve he was to expect that to happen. Unfortunately, the day was cut short when a police officer came to the school and took our little green haired child to the police station. And then his life changed.
Of course, it upset him. His parents were dead. He was distraught, but also on the inside he was kind of alright. His parents left him with a happy memory, and he remembered the last words he said to them before running out of the car to go to school. That kind of made everything alright. Right?
As he lay in the bed, quietly embracing his thoughts. He always was a thoughtful child in both senses of the word. He remembered the last things he said. The promise he made. He would fulfill it, and he would become the best of the best. Sure, he had his doubts, but he didn't have time for that. He had a promise to keep.
Katsuki quietly walked through the door and sat next to the grieving Izuku. He did his best to comfort the boy, but he could see something was different about him. Something other than the grief had struck the kind boy. It wasn't really anything to worry about, at least that's what Katsuki hoped, but it seemed as though the boy had a new glint in his eyes. Sure, there was still the Izuku they all knew and loved, although Katsuki would never admit it, that was going with him to his grave, but the boy was determined. Not an evil glint of vengeance, but one of certainty.
He smiled inwardly, looking back to his best friend turned adopted brother before quietly making his way to his own room. It had been a big day for the small Katsuki, and he was immediately out like a light. Izuku soon followed suit shortly after writing a few notes on the hero that had captivated him. His new brother.
Not long passed before the boys had signs of their quirks appearing. The ecstatic Bakugo family, they considered Izuku one of their own and he was more than happy to accept, took the young boys to a quirk doctor. Katsuki had explosions. It was fairly simple. He sweat, he make boom. He was happy with that.
Izuku on the other hand had a much more... interesting quirk as the doctor put it. It was unique, and a mutation of his parents' quirks (his father being basically a human battery, and his mother having weak telekinesis) and the doctor got to see it in action.
He was shocked, not literally but almost, and was writing up a short explanation from what he observed. Izuku could create a green lightning, which was what the quirk was dubbed as, and store it in his body at the expense of stamina. He could also direct it to various body parts to change various abilities of his and he could expel it in a fashion similar to Electrification, a more common electricity quirk. Rather than having his brain fried as a result, it drained his stamina and energy very quickly and overexertion could potentially lead to nerve damage of varying degrees.
The boys were thrilled by their quirks, and before long started practicing with each other. The next day of school, Bakugo was more than happy to show his off. However, when prompted, Izuku was far more reluctant and simply gave off a small green bolt. It left a mark where it hit, but it was so quick and weak that barely anyone noticed it. Some of the other kids started to tease him for it, but Katsuki shut them up. Rather quickly.
Perhaps this explained why the boys were inseparable for their schooling years, Katsuki had a deep care for Izuku and wanted nothing more than to protect his timid brother. At the same time though, Katsuki knew what Izuku's quirk was capable of, and they sparred frequently. None of the other kids minded it though, they much preferred the marginally tamer Katsuki when Izuku was around compared to the alternative. It wasn't much, but it was something.
Despite their obvious differences but also the fact that they hung out all the time, not a single student knew what happened that first day, and the situation they were living in together, but they were happy with that. They didn't mind. Of course, it definitely confused some students how much Izuku would change when talking to Bakugo (what they knew him as).
Them calling each other by first name was one thing (rather calling Bakugo by first name, everyone called Izuku that), but the way the timid Izuku suddenly changed into an entirely different person who was, somewhat, more confident but would also take shots at Bakugo despite it never being nearly as much as the shots Bakugo took at him.
Bakugo also changed, from someone arrogant and intimidating, to someone who had all the same qualities but with less of an edge to his insults, a much more back and forth and friendly albeit still challenging atmosphere. They had a very unique relationship, but no-one really paid much attention to it.
Bakugo's other... friends (but even he wouldn't call them that, they were more just people who wanted power) and many of Izuku's classmates all had the same question for him whenever Izuku wasn't around, "what is his quirk?". Bakugo, being the ever kind and thoughtful person, simply said that he wasn't going to say, and if they continued bothering him, he would blast them. Some kids asked regardless. They soon ended up with small burn marks on their hands after trying to stop him after he started walking away.
Bakugo did this for several reasons. One was that he knew Izuku didn't want to tell anyone, but the second was because he knew that Izuku was always training it to the point where he was ready to use it. Izuku was always concentrated in class, but even out of class and even if he were lying on the couch, and not writing his notes like his life depended on it, he was focusing on something.
That and the green flashes that came out of Izuku's room every night at the end of the day. He knew his brother well enough to see that he was building up his storage for his quirk, trying to make himself as strong as possible. But what interested him most was that every now and then there'd be an ever so brief arc of green lightning coming off Izuku by the end of the day. This only happened once he either stopped focusing on his storage, hence why it never happened at school, or if his storage started being exceeded. It would also show frequently during use whenever they were sparring, coming off of the appendages in question.
Chapter 2
Fast forwarding a couple years, and we can see our aspiring hero brothers on their last day of middle school. Their bond grew, and despite the unique family dynamic they had Izuku would happily call himself a Bakugo if it didn't raise so many questions. It was one of the final tests before the end of the year. Izuku then did something he had only done once before. He used his quirk in class.
It was a fairly simple maths test, but the way it worked was that there were 100 questions, and you would only be marked on those you attempted. Of course, you had to do a minimum of 20 and it was incredibly rare, maybe once every few years, someone would get around to completing all of them, and rarer still someone would get it all right. Let alone at the speed Izuku was going at.
Most of the class watched in amazement as Izuku's eyes began to seemingly crackle with a green lightning, and his hand had a few streaks of lightning in it too. His floppy green hair began to lighten and stand on edge as he blitzed through the test (and most of his pencil) in a matter of minutes.
Bakugo, sitting behind him, simply smirked as he watched the class's reaction. He also knew there was a part of the quirk they couldn't see, that Izuku was using it to speed up his thought process. He watched as the greenette quickly and quietly finished the test, handed it to the teacher and return to his desk where he began idly playing with the smoky remnants of his pencil. Everyone looked at each other in shock, before remembering that they had a test to do.
Bakugo remembered their last sparring session where Izuku seemingly developed a new quirk all together, with inhuman reactions. He brushed it off initially, but when the news later came on with reports of a villain attack and his mumbling had reached a whole new level of motor mouth he set a small blast off next to the boy to startle him and told him to spill (the new information, not the drink. That was already spilt).
What Izuku explained was that by directing some of the lightning to his sensory organs and brain, or mouth in this instance, he could accelerate them the way he could accelerate and enhance his other muscles.
Back at the test, Izuku was starting to yawn. The speed at which he made himself move was excessive, along with needing to make sure his eyes and mind could keep up with it, especially considering how little charge he had to run off of. The school day had only just begun. That's when he remembered.
He was in class. Suddenly he couldn't help but feel like wanting to melt through the floor. Maybe an invisibility quirk would've suited him better. But he did his best to ignore his internal worries as he focused on keeping his eyes open. He still had half a school day to go through. Great.
As soon as the rest of the class finished their tests, they directed their gaze to the now incredibly sleepy boy. Luckily for him, the attention was the perfect way to wake him back up. And remind him why he didn't use his quirk at school. He heard Bakugo whisper something in his ear, but he didn't register it. He was too busy panicking. At least until he felt an explosion next to his ear.
"Oi nerd! You finally manned up enough to show it eh?!" Bakugo... berated? They interacted... peculiarly with each other, but they seemed happy and the class didn't mind.
"Y-y-yeah I guess..." Izuku whispered in response. Bakugo proceeded to slap his back with a slight explosion.
"Took ya long enough!" He continued, startling the greenette.
"Yeah no thanks to a certain spiky haired blonde." Izuku snapped back. Bakugo smirked, his brother was back to himself and no longer dying of embarrassment. The class and teacher were baffled by their behaviour. They just sat there watching until Bakugo called out to them "Oi you extras are gonna catch flies with your mouths like that!", snapping them back into reality. "SINCE WHEN DID YOU HAVE SUCH A POWER- oi wait where'd the green haired boy go?" One of Bakugo's "friends" shouted. All that was left of the boys however, was a the faint noise of crackling lightning and the echoes of explosions.
The two had raced to the next class, the final class for the day. Bakugo noticed his brother still drowsy, if somewhat more alert. They had a P.E examination this lesson, with a twist to the normal ones. They could use their quirks, as long as they don't hurt anyone or damage anything. Whilst this did slightly irritate Bakugo, he was curious as to how his brother would treat it, considering that he just exposed his quirk to the school.
Meanwhile Izuku was doing his best to not panic and just focus on charging his quirk. From what he knew the P.E examination was nothing more than a beep test and a baseball toss. The simple stuff. He should be able to get away without using his quirk, right? He then looked over at his brother, who was smirking back at him. "Hey, wanna bet I'll throw further than you?" Bakugo challenged, trying to entice him to actually try his hardest. Izuku knew this, but wasn't going to let his brother better him this time. Today would be day zero of the new him. Well, sort of. The more confident him. Marginally, but still. "You're on." Izuku plainly responded.
Chapter 3
Izuku and Bakugo were so similar right now, it scared the teachers, let alone their classmates. Bakugo had a scarily calm aura to him, and Izuku was more confident and determined than they had ever seen him.
They had become so similar, both determined to do something. During the beep test Izuku dropped out early on, whereas Bakugo made it furthest in the class. Bakugo shot a determined look at his brother, both knew exactly what the other was up to.
After all, sparring, arguing, playing and competing with and against each other for their entire life meant you knew basically everything about the other. Then came what they were both looking forward to. The baseball toss.
Bakugo knew the longer Izuku took before his toss, the more power he could store, the further he could toss. But of course, Izuku knew this too and before you could say "You damn nerd!" Izuku and his motor mouth had secured last throw. He smirked at Bakugo, with a look in his eyes seemingly teasing him. Bakugo shot back a look that, quite simply, said "Get fucked – Sincerely your brother" which was his normal look but with slightly more aggression whilst also having slightly more playfulness and friendliness.
On the inside though, Bakugo was panicking. He knew Izuku had been charging for the better part of the last hour, and knew he'd have at least another 15 minutes before it was his turn to toss. Bakugo's mind was spinning, trying to think of something. He had an idea, it was desperate, but it might work. "Oi teach, I'll go before Izuku!" Bakugo called out. He had to plan this carefully, otherwise it wasn't going to work.
"And next we have... Katsuki Bakugo! Do your best, and feel free to use your quirk." the teacher called out. Bakugo knew he had to do this perfectly. He could already feel Izuku's taunting, he could feel the gaze on his back. "Yeah you can keep stalling Bakugo, but you can't stop the inevitable!" Izuku called, reminding Bakugo that the longer he took the more likely he was to lose. A smirk spread across his face, as he screeched at the top of his lungs, powering his quirk in his hand as the ball left. A fraction of a second too late for his liking, but he knew it was too late to go again. He launched the ball hard, the quirk propelling it. There was a brief cloud of smoke, and the ball was nowhere to be found. "713 metres." the teacher called out.
"Hell yeah, beat that Izuku!" He screeched, only to be met with a gentle, but determined smile from his adopted brother.
"Oh, I will."
Izuku moved to the throwing block, he had been charging for about an hour now. Nowhere near his capacity, and he couldn't dedicate everything to charging as he knew it would reveal the surprise early.
He smirked as he could feel arcs of lightning coming off his arm, with flashes of green in his vision. He heard the shocked gasps off his classmates and teacher, Bakugo excluded (who promptly yelled at them to shut up cause they were nothing but extras), but did his best to ignore it.
Time slowed down, he could feel his anxiety rise, slightly changing his plans. He could feel the power coursing through his right arm, up until the moment of release. He knew Bakugo sensed this as he heard a grunt from his adoptive brother, but he still threw the ball. Hard. Far. The lightning had not only given him speed, but strength, and with that he launched the ball.
Moments after release he shut his quirk off again, shooting a smirk at his brother. "Izuku, you got... 714?!" the teacher called out in surprise. His smirk only grew, has his brother admitted defeat.
"God damn it, fine, you win." Bakugo said, sticking out his hand.
Izuku responded with a fist bump instead "No need for the formalities, just do better next time." He replied with a gentle smile.
"Don't need to tell me that nerd!" Bakugo replied with a wide smirk. No matter how much of an effect he had on Izuku, he was still Izuku regardless.
Thankfully for his anxieties, Izuku managed to dodge a majority of questions, and Bakugo's presence definitely did ward off a majority of them to begin with. They were getting the stuff from their lockers, knowing they wouldn't have another day here. Leaving the locker lifeless and empty was a different sensation for both of them, but it was all put down to the same thing. Time for high school.
On the way home Bakugo and Izuku talked about their plans for the next few months. Izuku was lost in thought when it hit him. Rather when she hit him. He felt a rush of air, and in the few seconds he managed to turn around and brace himself, some of the lightning arcing off of his legs as he braced against the ground, and some off of his arms as he prepared to catch her. Time had seemed to slow throughout that, and suddenly it sped up again, and she crashed into him.
Thankfully from his quirk Izuku didn't completely crash into the ground, but only barely as he felt the strain on his legs. Looking down at the person who crashed into him, he didn't see much more than blue hair, and what appeared to be a UA uniform.
He could hear Bakugo stifling his laughter as Izuku began to go red, but he was quick to suppress his emotions before asking if whoever crashed into him was okay. "Yeah I'm okay! My name is Nejire Hado-" she broke off with a yawn. Izuku saw this and gently put her down but she seemed like she would collapse any moment.
"Ugh, I don't wanna see your sad ass attempt to flirt, I'll see you when you get home Izuku!" Bakugo called out over his shoulder, a smirk broadening across his face.
"Y-y-yeah okay, I-I-I'll see you later." Izuku called back in response. Izuku could feel his tiredness increasing as he had used his quirk more than usual. Making a mental note to improve his stamina whilst using his quirk throughout the day, he prodded the girl who had just crashed. "Hado-senpai, do you need help getting back to UA?" He asked, surprisingly confidently.
"Yeah, that'd be great but yo-" she broke off again, yawning as she collapsed towards him, her hair wrapping around herself.
Luckily with his quirk the journey was quite quick, and using slightly enhanced strength he was easily able to pull her onto his back and dart through the streets towards the imposing hilltop school.
He had made it to the entrance, where there was a cartoonish blonde boy and a shy, slightly emo, boy both anxiously waiting, along with an incredibly tired looking teacher. They saw flashes of green from the corner of their eyes as the greenette gently placed the periwinkle blue haired girl next to them, before using the remainder of his energy to get the hell out of there. He had recognised the teacher and was afraid the teacher would recognise him from his nightly... adventures.
The teacher noticed the flash of green but brushed it off, but soon noticed the girl lying there peacefully, delicately placed on the ground. He smirked, he had a pretty good idea of what happened but quickly wiped it off his face before the other two started asking questions. They had their focus directed towards the girl, who they carefully carried to recovery girl. She soon awoke, her first batch of questions were swift but all related to what just happened.
"Where am I? What happened to the boy who helped me? I wonder what his quirk was, it looked cool. Did Aizawa-sensei scare him off?" The boys and teachers did their best to answer as many of her questions, but she noticed Aizawa's deadpan expression had shifted slightly whenever she mentioned the boy. She was about to let the second batch fire off before the boys and recovery girl told her she needed rest. 'I just hope I can see him once he gets to UA. He referred to my name with formality, so he probably isn't in high school yet, but recognised the uniform so he definitely wants to come here.' She thought to herself, absentmindedly nodding along to Recovery Girl's and Aizawa-sensei's scolding.
Izuku, who had now made it home to be scolded by his adoptive mother, who was interrupted by Katsuki. "Oi old hag! He was busy helping someone out!" Katsuki called down the stairs, in his ever so loving manner. Despite her glare at her biological child, his mum softened her gaze to Izuku. "Alright then, well, just be careful and let me know next time." She told, to which he swiftly nodded in response. He then, using the last of his energy, dragged himself to his room and collapsed on the bed.
He reached out to his notebook, where he started a sketch of the girl he saw today, along with predictions of her quirk and what it would seem she'd be able to do. Based on her tiredness, he could tell that she, similar to him, used her stamina and energy to power her quirk. He soon fell asleep, the notebook in his left hand and pencil in his right. It had been an alright start to the month, but there was only so long before the entrance exam.
Chapter 4
A sleepy Izuku and his incredibly determined brother dragged themselves out of bed to go eat breakfast, before continuing their game of chess from a few nights prior. A surprise to everyone, Katsuki was actually an incredibly powerful strategist, only thanks to Izuku, however struggled to keep his head cool in most situations, so you didn't normally see this.
Izuku was still superior in this, although Katsuki wasn't going to admit this until one of their deathbeds, as he had an incredible ability to analyse, interpret and predict. Both of them knew this, so games they had typically took a very long time, having had spent so much time together they knew the other better than the other knew themselves and so they were incredibly competitive.
Even without using his quirk to accelerate his brain, Izuku was able to perfectly lure Katsuki and take advantage of his aggressive nature to take out piece after piece. "Checkmate." Izuku said, sticking his hand out. Katsuki smirked, responded with a fist bump and simply said "I'll get you next time."
"Bring it." Izuku responded, before stifling a yawn. "So what are we gonna do today?"
"School's out, time to prepare for the entrance exams I guess."
"Alright, so sparring, general quirk training, and..." Izuku trailed off, looking at the news. It was a report about Takoba beach, once admired for the natural beauty of it, was currently overrun by trash, both washed ashore and illegally dumped.
His mutterings were interrupted by his brother tossing a pair of ankle and wrist weights to him, a smirk on his face. "Let's go clean it then." Katsuki stated, knowing that would be the question at the end of his brother's ramblings.
They arrived at the beach, seeing large amounts of small litter, hard rubbish, even what appeared to be fragments of a shipwreck. They helped each other put the weights on and established the schedule. They knew they had to train both their ability to use their quirks, their raw physical abilities, and their combat abilities.
They decided they would spend the first week developing their quirk amidst sparring and cleaning the rubbish. The final three weeks before the exam would be dedicated to strength as they cleared the rest of the rubbish, and once their muscles were sore, they would take a 'break' by focusing on improving their capacity to use their quirk. For Izuku this meant dedicating time to charging his quirk faster, whereas for Katsuki focused on using his quirk repetitively.
During their first week of sparring, Izuku spent most of his time trying to develop a way to target from a range. He knew he could fire through the air but that was difficult to control at the moment, and it was far too easy for his sparring partner to dodge. During one of, probably several dozen spars between the brothers, Katsuki had initiated by flying through the air with one of his explosions propelling him, and Izuku directed lightning to his feet and head as he propelled away with a dodge and started trying to come up with a plan.
That's when it hit him (along with a ranged attack from one of Katsuki's explosions). Directing his charged energy to his feet, Katsuki could see the arcs coming off of his legs, and as soon as it appeared, it disappeared. Leaving Izuku with a smirk on his face. Katsuki knew this meant his brother had a trump card ready to play and swiftly backed off.
Izuku had directed a single streak of his green lightning through the ground, the shock hitting Katsuki hard. He smirked and came over to help his brother up. It didn't take long for Katsuki to realise what had happened, and knew he had a new challenge to overcome. Izuku had a few words of advice, and it sent gears in Katsuki's head spinning. "Why do you make explosions from your hands?"
Katsuki and Izuku returned to their positions, both knowing Izuku's plan. Because he was sparring with his brother, he didn't worry so much about hiding his quirk and stopped hiding the charged energy, and it began to arc around him, and hair began to stand on end. Although it looked like more effort, it was less because he no longer had to suppress the energy inside him. It was just an aesthetic difference. However, he did this to hide his plans from his brother, because he knew that, after sparring for so long, Katsuki would immediately notice the change in the arc patterns when he activated it on a particular target.
Katsuki on the other hand was lost in thought by what Izuku said. Of course, to him, it made logical sense that explosions came from his hands. It was easier to direct and control. But with his brother attacking through the ground, he needed to be able to propel himself upwards whilst still being able to attack.
A smirk broadened on his face as he understood what his brother said. Focusing on his feet, he started making small explosions, carefully propelling himself upwards. It was difficult to control, and jumpy, but it served its purpose Izuku smirked as he knew his brother had just unlocked new potential.
They charged towards each other, continuing the sparring bouts. They had become less about knocking the other out, but more about landing a single blow as that was hard enough in itself.
As the day went on, they finished sparring and began work on moving the garbage laid on the beach. Bakugo trying to fly around and collecting the smaller rubbish, Izuku using his quirk to improve his strength to move the fridges and freezers. They daren't open a single one, for all they knew there could a body in it (maybe their excessive horror movie watching had made their imaginations somewhat overactive).
Their first week of training continued like this, although occasionally being scolded by their mother for their use of ice and heat packs after pushing themselves so hard. They had barely gotten a quarter of the way through the piles of rubbish, although they did spend a lot of time sparring.
Then came along the next few weeks, where the ankle and bracelet weights would become more important. Raw strength and quirk capacity. This was going to be rough.
They started with different routines, whilst one was moving the various large objects the other was pushing their quirks to the limit.
For Izuku, it involved him using his quirk whilst supressing the arcs, charging it at high speed and using it whilst still needing to be able to move afterwards. For his brother, he was straining the sweat glands around his body, rather than just those in his hands.
After about two weeks they were almost done, both of the boys exhausted. Katsuki was kept home by their mother after he insulted her one too many times, so Izuku was off working on the beach himself. He was fitting the bracelet on his left hand as he saw a flash of blonde hair.
He thought it was Katsuki but knew even he wouldn't dare go against their mother's direct will. Finishing fitting the bracelets and ankle weights, he ignored it and began to charge his quirk. With no-one around and him not fighting anyone he didn't bother supressing the quirk. The charge was low, so the arcs of lightning were less, but still undeniably there. His hair didn't stick up completely but wasn't the same floppy hair he had without it.
He started moving the fridges and freezers before he saw the hair again. So he definitely wasn't imagining it, or he was definitely going insane. Great. "Wait, were you waiting out the front of UA the other week?" Izuku, feigning confidence, called out in the general direction of the hair.
"Yeah I was waiting for my friend, she had accidentally flown off into town. How do you know though?" The person, who had now stepped through the wall of hedges to reveal himself as the cartoonish boy from the other day.
"Oh y-y-yeah, I-I-I think I, uhm, saw you! Yeah! Waiting outside the f-f-front of the g-gates," Izuku nervously stuttered, knowing his lie would probably be caught but just tried to sail through, "S-s-sorry, I'm, uhh, not great with new people."
"Nah it's all fine man, but I swear I've seen your quirk somewhere before," The blonde boy had his suspicions, but knew he had friends like that. Well. A friend like that. He gave a thumbs up before continuing, "Like, electrification is common but green, and the way yours forms more akin to lightning, if I'd seen it before I'd definitely recognise it... wait... are you-?"
"Sorry, gotta go, cya later!" Izuku cut him off, blitzing away with streaks of lightning behind him.
The blonde smiled nervously but, in his head, knew that was him. He smiled to himself. 'See you at UA lightning boy'.
Izuku meanwhile was on the way home, taking a slightly different route. In his panic, he had managed to get himself slightly lost.
He knew the streets, but he wasn't anticipating going out of his normal path. Wandering around slightly slower than normal as he glanced around, he haired a scream that was quickly muffled. Something wasn't right. He could feel it.
He still had some energy at least and quickly directed this to his legs and head in an attempt to single out the noise. He heard the same scream, this time muffled. He felt the energy in his legs flow as he ran towards the noise.
Eventually he made it to a shady alley way. He had a decent reserve of energy still, but his muscles were aching. Luckily, his brain was fine and the moment he saw what was happening he immediately started planning. He saw that the sludge guy had someone has a hostage, but after watching All Might fight them before he knew if he was fast enough he would be able to go through the sludge guy and grab its hostage, hopefully being able to immobilize it with the slime solidifying around him from friction.
Seconds after taking in the situation, Izuku dived in with his quirk running full power on his legs and arms. He felt as though time slowed as he started moving at an incredible speed. He felt himself slow down as he reached the sludge villain, but still was capable of maintaining enough speed to burst through and grab the victim. He grabbed the victim using his lightning to make sure his grip was enough and focusing more of his energy on his legs he ripped them out of the villain's grasp with a burst of speed.
Time started to speed up again as he heard the villain screeching in pain. The extreme speed he moved at was producing so much friction, it made so much heat that the villain was solidified in the place he had moved through. "YOU LITTLE BRAT I'M GONNA TEAR YOU FROM LIMB TO LIMB!" It screeched, but despite it's threat it was in too much agony to move. Izuku knew this, and swiftly jumped away with the sludge victim's victim in his hands.
Eventually he made it to the open street in a less shady part of town. Taking a moment to think, he assessed the situation. He called the cops and directed them to the area he was just at, and then moved to the park. He was near the hill that UA stood on, next to a niche café and a construction site in its very early stages. He looked down at the person he had just saved, who were finally coming to. He recognised her as the girl he had caught just a couple weeks ago, as his eyes widened. "Hado-senpai?"
"Oh hey, it's you again!" She responded, "I think you can put me down now."
"Oh, R-r-right. S-s-sorry about t-t-that," Izuku stuttered as he began reddening and putting the girl back on her feet, "Are you okay now Hado-senpai?"
"Yeah I'm fine but y-" she broke off with a yawn again. And then fell asleep. In his arms. Again. This time, Izuku once more pulled her onto his back, his face reddening, before making his way back towards the school gates. He wasn't meant to be here until next week! Wait the entrance exams were next week. Crap. He just ignored that for now, and focussed on charging his energy once more, in order to get out of there fast. Again.
Once more he made it to the front of the school, charging his quirk, numbing his legs further and in no more than a matter of seconds the girl with periwinkle hair was lying next to her friends and teacher after a flash of green.
"What the?!" the shy, emo looking boy called out. Once more had one of his best friends gotten into trouble, seemingly disappeared, before reappearing lying next to him and his other friend and teacher with a flash of green. His blonde friend seemed to be lost in thought, as Aizawa-sensei picked up the girl and carried her to the nurse's office. "Problem child," He muttered under his breath.
Izuku had made it home a little later than usual, but not so late as to arouse suspicion. His mum welcomed him home as Katsuki merely grunted (he was fairly restless) and motioned to the chessboard, which he had set up. Izuku absentmindedly moved the king's pawn, which his brother mirrored. It was a fairly standard game opening for them, so he was flying on autopilot. His mind was preoccupied by the events of the day.
On one hand he knew that he had definitely developed his strength and his quirk (he just remembered to take off the weights), on the other he couldn't get that girl out of his mind. His brother was too focussed on the game at hand, so Izuku was able to be left to his thoughts.
"Check." Katsuki called out with a smirk.
"Check." Izuku called back effortlessly, simultaneously taking the offending piece and countering. Katsuki's face went back to the serious, if eternally scowling, face that Izuku was accustomed to when the brothers were together.
Back in his head, Izuku still had the blue haired girl in his mind. He wondered if he'd see her again. I mean, it's happened twice so far, who knows what'll happen next?
On the other hand, the girl had just woken up and was trying to figure out the location of her green haired saviour, to no avail as the boys and teacher both just shrugged and were trying to figure out if she was either delusional, or had a secret second quirk. The latter seemed really likely to them, as they saw but a flash of green and suddenly, she reappeared, unharmed and unaccompanied.
She sighed in defeat as her usual energetic nature was drained by the events of the day. She mumbled something about going back to sleep and that she'd prove them wrong, before returning back to blissful sleep in the nurse's office.