Chapter Text
“Kacchan, I’m not thirsty.”
“Drink it you fuck.”
“Kacchan.”
“What?”
“You’re fussing.”
“I am not. Shut your face.”
“Quit worrying. It’s gonna go fine.”
“I don’t want it to go fine. I want it to go fucking fantastic. Get out of here with that fine shit, Deku—”
“Don’t be a drama queen. Sit down and hold my hand. I’m frightened.”
“No you’re not, you’re playing Tetris on your fucking phone!”
“I think you mean I’m demolishing your high score on my fucking phone.”
“Fuck off you fuck.”
“You should put that on my headstone. ‘Fuck off you fuck.’ It’s beautiful.”
Despite himself, Katsuki felt the anxiety leech from his bones. It was hard to be absolutely terrified when the subject of your terror was gloating about his Tetris score and sipping water from an All Might thermos. He couldn’t eat anything before surgery, so in his head Katsuki was planning a brunch to end all brunches; following what was to be the most perfectly performed open heart surgery in the history of medicine.
Deku’s Doc eventually came in. Katsuki never bothered to learn his name, so he referred to him as such in any and every situation.
“Alright, Izuku, we’re ready for you.” He smiled reassuringly, as if Deku needed it. Calmness radiated off him like he was the fucking Buddha. Meanwhile Katsuki’s own apprehension tickled his lungs.
The scrub team arrived and started their prep. Katsuki was relegated to the corner of the room, awkwardly watching them check Deku head to toe and fit him for surgical scrubs. When they were done, Deku looked to him and silently held out his hand. Katsuki strode over and took it, giving his fingers a squeeze.
No matter how many times they did this it always felt like the first time to Katsuki.
Deku’s Doc was looking over his chart one last time when Inko-san burst into the room, hair in disarray. “Izuku!?” she cried. “Thank goodness. I was afraid I missed you. Oh baby how’re you doing?”
Deku smiled his heartbreaker smile and patted her hand. “I’m fine, mom.” He said. And he was, which was the annoying thing. He never balked in the face of potentially life-changing medical procedures — bravery the likes of which Katsuki could only dream of. “You didn’t miss anything. Kacchan even skipped school to hang out with me.”
Inko smiled tearfully and kissed her son on the forehead. She shot Katsuki a grateful look, which made his face heat up in embarrassment. As if there was anywhere else he would fucking be right now.
“Okay, team, let’s do this thing.” Deku’s Doc said cheerfully. “You ready, Izuku?”
“I was born ready.” Deku replied. “Literally.” That earned him a chuckle from the room.
They wheeled him into the hall and Katsuki didn’t let go of his hand until they were outside the double doors of the surgical suite. Deku tugged him down and leaned in to his space. “Love you, Kacchan.” He whispered.
Katsuki swallowed thickly. “I know, you damn nerd.” He said back.
And then Deku was gone. Whisked away by skilled hands to have his fucking chest cut open.
Sweat gathered in Katsuki’s palms, and he very carefully wiped them dry before going to sit with Inko-san in the waiting room.
Growing up with a best friend who’s sick is a challenge not easily described.
Katsuki and Deku’s moms had them at practically the same time, so even though they weren’t technically brothers, they were close. There was never time when Katsuki was and Deku wasn’t.
When they were four, and Katsuki got his Quirk and Deku didn’t, Katsuki was actually relieved. It was an awful thing to be, and Katsuki felt guilty, but Deku’s heart was no good for Heroics; he could barely be outside for more than an hour because his circulation was so bad.
When the other kids picked on Deku for being Quirkless, Katsuki punched their noses flat and blew them up. Deku never fought. He just smiled and told him it wasn’t worth it, tears and snot running down his face.
It made Katsuki hit the bullies twice as hard.
The first time Deku had an attack, they were in Katsuki’s room playing heroes. Deku fell facedown on the carpet, and when he didn’t get up, Katsuki panicked.
He screamed and their parents came running. Someone called an ambulance, and a man in a black shirt strapped Deku to a board and took him away. He was floppy like a dead fish, face blue and eyes half open.
Katsuki had never felt fear like it. To this day it haunted him. Fueling his worry and making his fussing a neurotic thing.
He learned later that Deku’s heart was broken, shaping the word “congenital” in his mouth until it made no sense. Katsuki thought it was bullshit. No one, no one, had a stronger heart than Midoriya Izuku.
The surgery went perfectly. “Textbook” said the surgeon, but he was a pompous prick so Katsuki waited until Deku actually woke up to make his judgments.
The little shit grinned at him in a drug-addled stupor.
His heart monitor blipped a steady rhythm, but Katsuki still felt for the pressure point in Deku’s wrist to be sure. Inko-san smiled and ran her fingers through his hair.
“Told ya.” Deku slurred. “Not t’day.”
“Yeah, yeah.” Katsuki rolled his eyes. “Congratulations. You lived.”
“I met God.” Deku said seriously.
Katsuki smirked. “Oh yeah?” He chuckled. “How was that?”
“It was awesome. She smells like lavender. And she’s got chainsaws for hands.”
“Sounds like my kinda woman.”
“Mine too.”
Inko giggled. It made the lines around her eyes dance playfully. “You boys.” She said fondly. “I wish I’d brought my camera.”
Deku fell asleep a little while later, so Katsuki politely excused himself and went to get food from the cafeteria. He sent his parents a text updating them on Deku’s condition, which they both responded to with a disgusting number of emojis.
He bought onigiri for himself and Inko-san, she tended not to eat when Deku was in hospital, and trudged back up to the cardiac unit feeling a little lighter. When he got to Deku’s room, Inko was putting on her coat and smoothing out the blankets around Deku’s feet.
“Oh, Katsuki dear.” She said when she saw him. “Is that for me? Thank you. I’m heading home to grab some of Izuku’s things before he wakes up again. He asked for his notebooks, silly boy. Will you watch him for me?”
“Of course.” Katsuki said.
“You’re a lifesaver. Call me if you need anything, okay?”
“Okay, Inko-san.”
She left and it was just him and Deku, who was utterly conked out. Katsuki sat down in Inko’s chair and pulled out the homework he’d been neglecting. He had Deku’s too, and fully intended to bully him into doing it once the bastard wasn’t high as a fucking kite.
He couldn’t let him fall behind now, not when they were so close to graduation. They were going to the same goddamn high school; Katsuki didn’t care if he had to drag Deku there by his fucking nose tube.
After that first attack, taking care of Deku became second nature.
Every morning, Katsuki would go over to Deku’s place and walk him to school. If he was breathing wrong, Katsuki stopped and let him rest. If he was thirsty, Katsuki pulled a water bottle from his back pack. When Inko was at work, Deku stayed with Katsuki’s family, and he helped his mom measure out Deku’s medicine in the morning and at night.
Another kid might have been annoyed by Katsuki’s nannying, but Deku just smiled and accepted it, letting himself be pushed and prodded into health by the world’s most explosive best friend.
He had another attack in the middle of winter, when they were eight. That was the first time Deku had to go into surgery, and Katsuki remembers biting his fingernails into bloody stubs during the long horrendous wait.
The doctors told them that Izuku needed a new heart.
Everything in Katsuki rebelled at the idea. Deku’s heart was fine. It was perfect just the way it was.
“You’re serious.”
“As a fucking heart attack.”
“Ha ha.” Deku was groggy, but lucid. “I hate to break it to you, Kacchan, but my chances of getting into U.A are about as skinny as a coked-up thin mint.”
Katsuki crossed his arms and glared. “I’m going to U.A.” He growled. “Which means you’re going to U.A. Get it through your thick skull, Deku. I’m not leaving you behind.”
“You’re so dramatic!” Deku threw his hands up, wincing when he pulled his IV. “Going to U.A is not ‘leaving me behind!’ It’s following your fucking dream. You don’t need me there pulling you down.”
“Is that was this is about? You think you’re holding me back or some shit? That’s bullcrap and you know it. You’ve wanted to go to U.A since before you could fucking walk, and this is your chance. So stop being a little bitch and say yes already!”
Deku frowned mulishly. The stubborn cuss wouldn’t even look Katsuki in the eye.
“Look.” Katsuki tried again, more gently this time. “I don’t want to do this alone. I can’t do this alone. I don’t want to go to some big dumb hero school if you can’t come with me. That’s just how I feel.”
Deku’s gaze flicked up to his, searching. A moment later he sighed, deflating into his bed. He looked exhausted, dark rings like charcoal around his eyes.
“You realize that me getting in is a one in a million shot, right?” He said. “Even if it’s just the Gen. Ed Department?”
Katsuki grinned sharply. “I’m aware.”
Deku smiled tiredly. “Then let’s fucking do it.”
Katsuki cackled.
Broken heart my ass.