A/N: On Our Way - MercyMe
I adore this song and if I had to pick a single song to carry this entire fic, this is it!
I can see Izuku and Katsuki bonding at the beach house. I can see them running and laughing across the sand and fighting in the water playfully. I can see them becoming a team and learning to rely on each other. I can see them working through all of their problems together and running through the city with smiles as they get to follow their dreams as pro heroes. I can see them battling villains and winning...and when the song drops to something a little less upbeat I can see what happens after that fight.
The annual class New Year party.
Katsuki hated it, but it was the one social event each year his so called friends would not let him bail on. One year the pack of them had even showed up at his door to drag him out to attend despite his grumbling and threats to blow them all to pieces. Annoyingly, after years of making such threats and baring his teeth at them, they hardly batted an eye at it now.
The annual event was the one time a year Katsuki would glimpse Deku before he had moved back up his way for work and although Deku wouldn't approach him at all, their eyes had connected more than once over the years before both diverted their gaze – Katsuki making a point of stubbornly holding the glare until Deku was the one to glance away first so the blonde could call it a win at least.
This year though was the first time he was attending with the nerd. They lived close enough to one another to catch a train together to the next city over where a fair few of their old classmates lived and worked and the rest of their class would find their way there for the evening from all over the country. It was the one time each year practically everyone from their class A days would be together in the same space as many of them were given holiday time over the Christmas to new year period.
But this year was to be different.
It was the first time Katsuki had found himself in such a compact yet crowded space, everyone buzzing away with conversation and yet to him it was silent. Usually the noise would have been annoying, everyone having to lean in close or yell to one another to be heard over music that Sero and Kaminari would always gain control of and turn up too loud. Katsuki figured that this was what a silent disco must look like to an outsider. Some old classmates were dancing, others visibly raising their voices to be heard by one another and louds bursts of laughter as some tipped back their heads with wide smiles. Yet it was completely silent.
Deku was right by his side as they stood in the doorway having just arrived and surveyed the area. Seemed they were one of the last to arrive. Kirishima was there and Katsuki could see the red head smile and wave their way before starting to come towards them.
Deku nudged at Katsuki's side gently to get his attention, his green eyes and soft smile patiently waiting for Katsuki to look his way.
Will you be alright? He asked and of course that got Katsuki's blood boiling. As if he wouldn't. Rather than signing a response Katsuki just lifted his lip in a sneer to the greenette and flipped him off before Kirishima was before him with a wide smile and already lifting his hands to sign away at him. Deku's smile widened at Katsuki's response. He turned and nodded a greeting to the red head and then stepped further in to no doubt find his own friends among the crowd.
Katsuki turned his red eyes, narrowed with annoyance, to Kirishima who signed him an enthusiastic greeting and moved to usher his towards the cluster of friends he had been with moments before. Behind him he could see Uraraka raise her hands with a wide smile to celebrate Deku's approach and the green haired idiot smiled back at her.
Katsuki followed the red head till he came to a stop among a cluster off people on the far side of the room beside the floor to ceiling windows that over looked the city scape. From memory, Deku had spelt out that this was Jiro's place, her design taste consisting of a lot of sleek black furniture with a splash of red here and there. The cluster of people consisted of his old social group at high school, an enthusiastic Kaminari smiling his way with a pathetic attempt at signing a hello and Katsuki rolled his eyes in return. Now that it was common knowledge that he was deaf, he hadn't stopped to think what everyone else would do with that information. He hadn't really thought that any of them would start to teach themselves sign language, Katsuki had just figured that he would be free from their nonsense.
Hello B.A.K. –
Katsuki slapped away the other blonde's hand with a scowl, growling out that the idiot didn't have to spell out his entire fucking name because that was just wasteful time wise. That and he was the only bloody deaf person in the room. It was pretty obvious who the sign language was for.
Sorry, the blonde tacked on with a grin. Irritating Katsuki was still one of his favourite things to do and annoyingly the less often they saw one another, the more eager the zappy man was to piss him off.
How have you been? Waved about an exited Ashido, her hair bouncing with her excited movement. Katsuki was sure that if it wasn't for the proper wording of the sign language that she would have said it more along the lines of 'how've ya been' and Katsuki couldn't decide if he preferred it that way yet or not. Katsuki looked her way, his irritated face relaxing some as her joyful racoon eyes waited for him to respond with almost bated breath. Katsuki merely gave a nod and grunt that roughly translated to a 'fine' because saying more would probably just encourage them to continue conversing with him and their sign language was so rough that he doubted they knew much beyond the basic greetings and phrases. Ashido grinned at his response.
You and, she raised a hand to point beyond Katsuki's shoulder and the blonde turned to follow the direction of her finger to see it pointed Deku's way across the room as he smiled and talked with Uraraka, Todoroki having come to join them as he sipped at a drink and listened to his words with that same damn old stoic face. Katsuki turned his head back to look to Ashido as she lowered her hand again, but her smile was still wide and bright.
The pinkette floundered with her hands for a moment, not knowing how to sign what she intended to say so Kirishima stepped up from beside Katsuki, the blonde's eyes turning his way, as his more experienced hands translated her words.
She's asking about when you and, he jerked his head in Deku's direction too, decided to become a team.
Katsuki rolled his eyes with what felt to be a light grumble in his throat. They had already covered this shit when they had first gotten their solo permits and he said as much with crossed arms. Ashido rolled her eyes with a smile.
She waved her hands about again with an eye roll and Katsuki had to narrow his eyes at her movements to get the gist of it. Her flailing movements roughly translated to: Yeah, but how?
Figures. Always the gossiper and needing to know everyone's business. But Katsuki refused to budge and say anymore than had already been said because he just couldn't be bothered and he already knew Ashido's nosey questions would never end.
A cold touch to the nape of his neck made Katsuki flinch forward, turning a glare to face a grinning Sero holding a chilled can of beer his way in offering. He snatched at it with a snarl before the raven haired man with a stubbled chin came around to stand with the others who were giggling at Katsuki's reaction. The blonde only glowered at them and sipped at his beer, irritated that he couldn't hear someone sneaking up on him.
They chatted, or more so everyone else chatted around Katsuki for some time, Kirishima making an effort to sign for his old classmates whenever they failed at it or directed words his way. After a while though Katsuki stepped away. Outside of the old gang, very few others had learnt sign language to communicate with Katsuki with. It's not as though he had hoped or expected them too and right at that moment, being away from flailing hands that he was supposed to give his undivided attention to was nice. If everyone did it he would wish himself blind too.
His wrist buzzed and Katsuki lifted his watch to read text rolling along the bottom of the screen.
Deku: Done with the night already?
Katsuki frowned at the watch before letting his arm fall back to his side and turning away from the window to look across the room for Deku. He found the nerd in a far corner, among some sort of curvy sculpture that made no sense to Katsuki whatsoever. It looked like Yaoyorozu was talking about the apparent piece of art to the small group gathered there but Deku's green eyes were solely on Katsuki across the apartment. The greenette shot a smile Katsuki's way who refused to flash his teeth in return, turning his back on the nerd to continue nursing his beer whilst he watched the view of the surrounding city buzz with life despite the cold outside.
His peace didn't last long before an elbow gently nudged at his and Katsuki slowly turned a glare Deku's way, the greenette having joined him. Deku had no drink in his hands, leaving them free to sign.
You didn't reply, he signed to Katsuki with a small grin, clearly not actually annoyed about it. Katsuki just sipped at his beer some more, turning his attention back to the window. Deku's hands moved and despite the want to ignore the other man, Katsuki's eyes still looked to the side to read what he had to say.
Are you bored? He asked
Katsuki inhaled deeply and let the can down at his feet before raising his own hands to reply. He had no intention of trying to regulate his voice here while he couldn't here how loud the surrounding noise to compete with was.
Are you? He threw back Deku's way, you wouldn't be bringing it up unless you wanted to leave.
That's not true, he rolled his green eyes, I would leave if you weren't enjoying it and –
You think being stuck on a train for an hour with you would be more fun that being here, Katsuki interrupted him with an eye roll of his own. Deku shook his head lightly at the attitude.
So what, you want to go? Katsuki added on.
You do seem bored, Deku insisted, and I'll admit I don't feel at my best. Katsuki frowned at Deku with judgment at that.
You drink too much again like an idiot? Katsuki signed at him, but Deku simply shook his head with a small smile.
Fine. Let's get out of here then. I'd rather sleep anyway. A roll of the eyes and a lifting of the corner of Katsuki's lip with a sneer was all that had to be done for Deku to nod his agreement before Katsuki bent to pick up his can to throw in the bin on his way to the door, the nerd taking an extra moment to say his farewells. While Katsuki waited at the door with his hands in his pockets and a frown on his face, Kirishima spotted him there and lifted his hands to sign from across the room. Another useful thing about sign language Katsuki supposed.
You leaving already?
Katsuki merely jerked his head in a way of a nod and the red head went on the sign that he was sad that Katsuki was leaving so soon - despite it having been at least two god damn hours - and said his own farewell before Deku finally made it to the door and away from his clingy friends and they left for their own city.
Deku had always gotten on Katsuki's nerves, that was a given with his bright optimism and smiles that were almost blinding at times. They were such opposites in so many ways that it almost made Katsuki's head hurt and ever since agreeing to partner with the nerd he had spent more time around him than he had since, well, ever. When they had been tiny brats they would play every chance they had and beg their parents for sleepovers and everything. They saw each other five days a week at kindergarten and spent at least one day over the weekend playing and promising to be hero partners when they grew up. In elementary school they weren't in the same class but still glimpsed each other walking to and from school, though at that point things were starting to get rough between them. Because despite Katsuki's shift in attitude, he had also felt betrayed back then and lied too. Deku had broken their promise of being a hero duo, because how could he when he was diagnosed as quirkless. Back then Katsuki hadn't understood and he had begun to lash out at his old friend to vent his own frustrations.
In middle school they were in the same class two of the three years there and then come high school, well, they were stuck with each other for three years straight, both in class and in the dorms. They didn't always interact during class and during their evenings and weekends in the dorms but they generally saw each other each day. Then went by the years of nothing and then back to this. Now Katsuki saw Deku six days a week for hours on end. They would meet for meals, patrol together, train together, go to interviews and catch up with friends together. All in all they spent at least more than twelve hours with each other each of those days and Katsuki sometimes thanked his ears for not working because he doubted he could be around Deku that much if he had to endure his mumbling and voice that long each day. As it was, their one day off a week was the only day they didn't see one another.
Everything was going great. After being back on the hero scene for four months they had narrowed down their choice of agencies to join once the year was over - unless a better offer came along. Their gruelling solo work was paying off and Katsuki felt a sense of deep calm inside knowing that as long as Deku was at his side, he had a secure future as a hero.
That was until it all came crashing back down.
It was late February when they had been patrolling and got the call. Or more so, Deku got the call and then passed on the information to Katsuki via their watches. An SOS of sorts. A group of heroes facing a villain on the other side of the city were getting their asses kicked and had sent out the call for backup. Katsuki sent back a message of his own to Deku who was no doubt somewhere up high where he could see Katsuki and much more around them. All Katsuki had to do was raise a thumb into the air above his head and his wrist buzzed with Deku's acknowledgment and then they were off, the message having already given the location. Working with Deku was good because even when taking to the air, Katsuki never had to look back to see if Deku was keeping up with him because he already knew the nerd was.
The scene they came across was a mess. They had passed over a police barricade where nosey reporters and stupidly curious civilians gawked on from. Beyond the barricade were crushed cars and damaged buildings, their faces pulverized and the chunks of debris littering the road. Not far up ahead was the villain, a large bulky individual who stood almost three times the height of the struggling heroes surrounding them, their attacks going almost unnoticed by the muscle swollen villain. Deku's message had said something or other about an attempted robbery that the villain must have gotten busted trying to pull off before turning into the monstrosity that was before them. Not that Katsuki cared. All he cared about was the chance to show the stupid heroes of the city just how much better he – and Deku – could handle the bad guy.
They were smooth, a well trained duo, as they swept in to attack the villain from above on either side. Katsuki didn't even have to look back to know that Deku had peeled off from behind him to his right to land his own blow on the villain because with a simple vibration along the right side of Katsuki's smart watch, Deku had communicated his movements to him with ease. It was thanks to the pair's long history of sparring that Katsuki already knew Deku's intentions in battle without having to ever speak the words.
Despite being unable to hear his own voice, Katsuki blasted himself to the left of the villains head, yelling out a taunt to get the fucker's attention. It's big ugly snarl turned Katsuki's way and he returned the look with a smirk as he brought his hands forwards and released a Stun Grenade attack to blind the villain, who tipped back their head with what Katsuki could only assume was a roar. Katsuki had closed his eyes before his attack and the moment he had ended it, his body still in mid-air, he opened his ruby eyes in time to see Deku swinging his leg wide and landing a blow across the back of the villains head with a sparking green kick, his eyes still closed as he did. The villain was pushed forward from the impact with what looked to be another, probably more pathetic roar as he began to fall forwards, stunned twice over in a matter of mere seconds.
Deku's green eyes shot open, taking stock of the result of his strike and opened his mouth to call some warning to the extras below, but being pro heroes, they were already clearing space for the body to fall into the street, the nerd having gone so far as to strike the villain with the intention of them not landing on any more structures. Katsuki was looking forward to the moment his feet would touch the ground and he could bark at the extras for being so useless when he and Deku could clean up their mess so quickly, but before the body hit the ground, their arms came forward to catch themselves and began to rise again with a snarl. Katsuki narrowed his eyes with a snarl of his own. A challenge was always welcome after all.
With a couple of blasts, Katsuki regained his lost altitude while Deku touched the ground, still sparking with green, and pushed off again, coming back up with a raised fist and landing a blow under the villain's chin, knocking them back and off balance to fall down the other way. To drive the point home, Katsuki positioned himself above the falling villain, bent his legs at the knees to point his knee guards downwards and blasted behind himself to bring himself down with force, his armoured knees colliding with the villains chest and pushing him down faster to the asphalt below. Katsuki landed with a fierce smirk, knees bent and at the ready to dive into action again if needed as the villain's head finally collided with the ground. Deku landed only meters away, sliding to a halt with green eyes fixed on the villain, watching for movement. After a moment had passed, Deku let his body relax a fraction, turning his face to look to Katsuki who smirked the nerd's way and the greenette shot him a smile in return.
Then the ground shook.
The villain was roaring with enough volume for Katsuki to feel his eardrums quivering, Deku and the other extras in sight raising their hands to cover their ears against the audible onslaught. The bad guy was rising again, grotesquely large arms moving to pick themselves back up and Katsuki could almost swear that the villain had grown in size again or perhaps still was as he was forced to move back to avoid a giant hand coming his way to squish him like a bug. Beyond him, Deku had recovered enough to lower his hands again, the roaring dying back down in time for himself to leap back to avoid being swatted like a fly.
The pair of them along with the extras around them tried time and time again to down the villain, but they had grown in enough mass that Deku's blows couldn't knock them back down again without risking damage to the surrounding area and Katsuki's blasts were ignored as they did little more than sting at the villain. More than one hero weren't quick enough to dodge a swatting hand thrown their way and were out for the count. So they had to up their game.
Katsuki launched himself up ahead of the villain who had been slowly but steadily making their way down the evacuated street and causing more destruction with each step and pointed his gauntlets towards the villain. The villain's beady eyes fixed on him, mouth opening and showing teeth as they let out what Katsuki could only assume was a sound of annoyance, but not loud enough for Deku, who had floated up behind the villain, to need to cover his ears again. The villain raised an arm ready to strike at Katsuki but the blonde had full faith in his partner's Black Whip that lashed out to wrap around the villains arm and hold it in place. Frustrated they gave their arm a firm pull and without his feet firmly on the ground Deku was being pulled along with his quirk before he shot out more tendrils from his other arm to fix himself to a building, his body being pulled between the two as the villain fought on, mouth opening wide with another roar that Deku could do nothing more than close his eyes tightly against, unable to cover his ears as he refused to let go of his hold. And Katsuki wasn't going to waste the opening Deku was giving him.
He let loose both gauntlets at once, the stored up sweat being activated and creating a strong blast, strong enough for the rush of air to push Katsuki's body back, flipping in the air before he used a few quick blasts to right himself and landed on his feet. The blast didn't make the villain fall though, instead they scrunched up their ugly mug and were forced to take a step back, giving Deku's Black Whip some slack to work with. The greenette's feet touched the ground and with more stable footing, he grabbed a hold of the whips still attached to the villain with his other hand and with a grimace gave a strong pull, his movement being the tipping point and the villain finally fell back down. Moment's before the villain's body hit the ground, Deku released his Black Whip only to send it out again, wrapping around the villain's body and binding their bulky arms to their sides before they finally hit the asphalt and with their arms bound, unable to stand again. They struggled though, Deku grimacing as he fought to keep Black Whip focused and strong until another hero arrived who could send the villain into a peaceful slumber with their touch and finally Deku could release his hold on the villain and the police could take over, the greenette's shoulders slumping from the effort.
They were panting and bruised but they had done it while all the others had fallen short. The Wonder Duo stood strong. With the villain out for the count and the police in control, the line holding back the reporters and civilians was lifted and they came rushing forward with excitement, no doubt cheering loudly at the duo's efforts. Katsuki turned his head just enough to the side where he knew Deku was standing and shot the nerd a smirk before stepping forward atop some rubble. A quick glance over his shoulder was all Deku needed to see to know to follow, stepping up to be beside Katsuki again though his shoulders still hung low with exhaustion. The fight had gone on for the better part of thirty minutes, a long time when you're a pro hero as far as Katsuki was concerned, but he didn't feel as tired as Deku looked. Next time they were at the gym together, Katsuki told himself that he would force the nerd to focus on their cardio for a good long while to get that damn stamina up some more. After all, he couldn't have Deku dragging him down.
Side by side like the perfectly balanced team they were, Katsuki lifted a fist to the air, his thumb pointed down at himself. Out of the corner of his eye he could see Deku do the same – minus the thumb part – in victory and the crowd before them lit up in cheer again. Camera's flashed, reporters spoke into their mics, fans waved hands in the air wanting their attention as they both smiled on – Katsuki with more of a smirk than a friendly smile like Deku's.
Movement caught Katsuki's attention to his right as Deku was the first top lower his fist heavily to his side, the limb swaying with exhaustion. It was weird really how exhausted the nerd seemed. Katsuki had trained with him, gone to the gym with him and worked long hours as a pro without the greenette ever looking as tired as he did now. Katsuki was slow to lower his own arm, more movement from Deku out of the corner of his eye catching his attention, not because the nerd was moving as such but more because the movement was just wrong. Katsuki turned his head to point a stare the nerd's way but Deku didn't look his way. The nerd's head hung low, his green eyes almost unseeing as he swayed on his feet, both arms heavy at his sides. It was like everything was moving in slow motion and Katsuki could see it happening before it happened. He could see that Deku was about to drop and more than anything that struck at Katsuki's chest like a spear with concern for his partner because it wasn't like Deku to be so exhausted after a fight like that one. It wasn't like Deku to sway on his feet and look so unfocused. It just wasn't him at all.
The nerd continued to sway unsteadily, the eyes and cameras of the reporters following Katsuki's gaze towards Deku as the nerd shifted a foot back to catch himself but ended up doing to opposite. He slipped but managed to catch his footing rather than fall and for a moment Katsuki felt he could breath again. Deku was fine. Until he wasn't. The greenette may have stopped himself from slipping off the rubble but he didn't lift his head and before Katsuki could open his mouth to call for his attention, the nerd swayed one final time before gravity took a hold of him and he fell forward to meet to ground.
Katsuki had been making his way down the drab hospital halls when he finally found his way to Deku's door having not been allowed to linger after he had been admitted. The door was closed but when he went to open it he paused, bringing a slither of the room into view. Inside Izuku was sitting up in a hospital bed, fully awake and alert from the evening before but he wasn't alone. A doctor stood by the bed, his back to the door and whatever words were leaving his mouth looked serious judging from the tight frown and drawn brows upon Deku's face.
Being sneaky wasn't his style, so Katsuki straightened himself and opened the door fully like he had just arrived, stepping inside before slowing his pace as he neared the bed. Deku's frown withered into something worse for a second before he forced it to relax and the doctor looked from Katsuki back to Deku in silent question. Deku turned his eyes back to the doctor and opened his mouth to say something, probably along the lines of 'he's deaf so you can keep talking' before the doctor gave a nod and continued on with whatever he had been saying with a serious expression. Deku didn't make a move to sign for Katsuki so he stood a little ways off from the other side of Deku's bed with a frown and waited. Deku not making an effort to sign for him when these days Deku signed anything and everything just in case Katsuki wanted to know what words were flying around the room, even if none of those words were directed at Katsuki, was odd. That didn't sit well with him. After another couple of minutes of the two exchanging some words, the doctor finally left and the moment the door closed behind him, Katsuki turned his eyes on Deku.
I wasn't expecting you, Deku signed his way and offered a small smile but it seemed forced.
Katsuki grumbled back that he was the nerd's partner and it would be weird if he didn't come by with crossed arms and a huff. On top of that he asked what the hell was going on with narrowed eyes. The doctor's expression had been enough for Katsuki to know that Deku collapsing hadn't been a case of mere exhaustion.
The greenette pressed his lips together at that and pointed a finger in the direction behind Katsuki, the blonde turning with narrowed eyes to see he was indicating a chair in the corner of the room and Katsuki went to grab it, bringing it to the bedside and sitting down when Deku gestured for him to do so.
Deku tilted back his head, closed his eyes and took a deep breath like he was trying to calm himself before he returned his gaze to Katsuki and lifted his hands to sign. His hands quivering a fraction.
I haven't been honest with you Kacchan, Deku signed,I haven't been well for a while. He paused there like he didn't know what words to sign next and Katsuki found himself sitting perfectly still, waiting with growing impatience and a narrowed stare. Usually he would have snapped at him to spit it out already, yet he didn't. Because something in the calmness of Deku's green eyes made his heart freeze.
I had hoped that it wouldn't be a problem so soon but, he paused, forcing himself to sign the rest, My heart, it's been getting weaker for a while now and –
What the fuck.
Katsuki spoke the words aloud, cutting off Deku who merely blinked at him with lips parted.
Alright, so he wasn't well, something was wrong and the nerd would need time off to recover and get it fixed and then they'd go back to kicking ass together and –
Deku's lip turned up into a small, sad smile and he closed his eyes to shake his head gently before opening them again, looking to Katsuki like it hurt him to do so.
I can't get better Kacchan, he signed and Katsuki sat straighter, eyes narrowing even further.
Asking firmly to know what the fuck that was supposed to mean left Katsuki's lips harshly before he could think better of it and Deku only looked to him like he was guilty over it.
They can't fix it, Deku answered.
Katsuki's jaw tensed and he lifted his hands to sign so he didn't have to unclamp his jaw.
Ask Recovery Girl – who was surprisingly still alive if frail.
Deku shook his head.
It can't be fixed, Deku reaffirmed.
Someone –
They can't, Deku pushed on with a gaze that was trying everything he had to push that message across without it hurting.
Katsuki paused, narrowed eyes scanning over Deku's face thoroughly.
Kacchan, Deku hesitated, I'm dying.
For a moment Katsuki was still.
Then it registered and he stood, demanding to know who had told Deku that bullshit. But Deku just blinked up at him calmly with that same stupid sad smile like he had already accepted it. Katsuki went to turn, to hunt down that doctor and demand answers in writing if he had to and then he would burn it in front of the doctor. Before he turned away there was movement out of the corner of his eye and he turned back with a scowl to see Deku waving for his attention. He pointed to the chair again, asking Katsuki to sit but he remained standing where he was, glaring back at Deku with fire in his eyes, so Deku went on to explain anyway.
You know how my quirk stockpiles power from each generation, his signs weren't perfect but since Katsuki already knew the gist of One For All, he could follow, they told me once that I would be the last holder.
Katsuki's breath caught from the meaning. He had heard that before, back in high school during one of their little group meetings. At the time they had all thought it was said because it meant that Deku was the last person to use the power to finally bring down All For One and that once that threat was gone he wouldn't have to worry about finding a successor and passing it on.
I didn't realize this is what they meant, Deku went on, his gaze lowering as he continued to sign, it's gotten too strong. I didn't know but it's been catching up with me for a while now, he let his hands lower to his lap, his little explanation over. He didn't look back up so Katsuki kicked the underside of the bed to get his attention, choosing to sign, not trusting his voice in the moment as he didn't know how he would sound, whether he would sound angry or upset.
Heart transplant, Katsuki threw up as a solution. Easy.
That wouldn't solve anything. That heart would just become damaged too, Deku signed in reply, all hint of a smile gone.
Then give the quirk to someone else, Katsuki stepped forward. He didn't like the idea because that meant Deku would have to give up being a hero and so would he in turn, but it beat fucking dying. Deku shook his head again. Why couldn't the dweeb just accept a solution.
I can't do that. That person would be worse off than me.
They don't have to use the damn quirk, Katsuki threw back with annoyance. If they never used the quirk then it wouldn't be a problem. Done. But again, Deku shook his head and Katsuki was this close to grabbing him by the shoulders and shaking him.
It's too late for that. It will hurt them even if they don't.
Katsuki bared his teeth.
So what, that's it, you're just going to lay down and fucking die? Deku didn't answer, his eyes closing slightly with sympathy and the corner of his lips turned up with sadness again and that made Katsuki let out a rumbling growl.
Why didn't you tell me? He signed, anger swelling inside him.
I wanted to support you, Deku replied, his smile growing and becoming more meaningful, I didn't want you to give up being a hero.
It's killing you.
You're a hero Kacchan, we both are and we do great together. I don't want to let that go. Deku's eyes and smile were pleading for Katsuki to understand but all Katsuki felt was anger flaring up inside, drowning out everything else. He had tried being calm, being reasonable for Deku's sake but that had come to nothing so now he gave in to his frustration and let it guide him.
Being a hero is what's killing you.
Being a hero is all I've ever wanted. All we've ever wanted. I can't stop now.
The sickening feeling that Deku was being such a stubborn idiot and throwing his health and life away just to keep playing hero – so Katsuki could keep playing hero – tore at his chest. He was to blame. If he had never agreed to partner up with Deku for his own sake than maybe Deku would have given up on being a hero altogether after leaving the agency. Maybe he would have decided to do something else rather than hurting himself further every time he used his quirk.
Even if I wasn't a hero, the quirk would still weaken my heart. I can't escape it even if I just sat at home instead.
That damn nerd. It was like he could see right into Katsuki's mind. But by being a hero Deku was damaging his heart faster than he would if he did just sit at home or have a mundane life.
Katsuki lowered his gaze, hands balling into fists at his side before he made his decision. He pulled at the high tech watch at his wrist, throwing it Deku's way to fall on his lap and just like that, he turned and left, his last words telling Deku what a stubborn idiot he was and that they were no longer partners.
He didn't stop to look back to see what expression Deku wore at that as he stormed away with an angered scowl.
A/N: A little bit on Izuku's health:
Being the 9th holder of OFA, despite preparing his body for the quirk, it takes it's toll regardless as with each generation/passing it became stronger and stronger to the point that even while sitting idlily within it's host, it is causing minor damage to Izuku's heart. Although it took years for Izuku to notice any health issues (beyond broken bones and torn ligaments) once he had noticed them, the damage had already been done and his heart was left weaker than it was before. Using OFA only causes more strain and harm on his heart and the more he uses/pushes himself it the worse it gets. The damage is irreversible in the sense that as long as OFA is within Izuku, the quirk will continue to harm him and although healing quirks such as those from Recovery Girl or Eri could temporarily reverse the damage, it returns faster than it did before and is therefore only a temporary fix. Knowing this, doctors would not allow Izuku to have a heart transplant (plus Izuku doesn't want it) because a new heart would become damaged overtime too due to the quirk's presence. Izuku also refuses to pass the quirk onto a 10th holder because that persons body would be put under even greater stress than Izuku's currently is and would become damaged and Izuku wouldn't wish that upon anyone, not even the worst of villains.