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Part 2 of Nitroglycerin's Parables
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2019-08-07
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Nitroglycerin's Bark Is Deadly (But You Should Still Fear It's Bite)

Summary:

People didn't think about Katsuki's quirk that often. Not beyond the surface level.

He made explosions. It was very straightforward. What else was there to know?

Childhood promises were made, and sometimes children don't get to learn things the easy way.

Notes:

This is a little drabble I've had stuck in my head for ages that I wanted to get out. I don't see the drawbacks to Katsuki's quirk addressed as often as I'd like, so I decided to explore one possible route.

Work Text:

When Katsuki was four years old, he got his quirk.

 

At first he loved it. People told him all the time how impressive it was. How pretty his sparks were. How much good he would do as a hero. 

 

Some of the drawbacks were obvious, he had to be very careful about what he did and didn’t explode. It wasn’t always easy, but Katsuki knew he could figure it out. He knew better than to make people or important things explode. People knew not to try and touch him when he was upset too, that made it much easier. 

 

As it turns out, it wasn’t the explosions they should’ve feared. 



Both he and Izuku were five. Izuku hadn’t found out he was quirkless yet. Katsuki had lots of people who followed him around, but Izuku was different. Unlike everyone else, Izuku touched him. Not uncomfortably, but Izuku liked hugs and holding hands and cuddling. Most boys their age had grown out of that stuff by now. Izuku hadn’t though, he still loved to touch Katsuki. A few times they even practiced kissing together. 

 

When they were five, Katsuki tried to make him stop. It was weird to touch your friend that much, right? Other kids made comments about it. Telling him to stop made Izuku sad though, which was completely unacceptable. Heroes were supposed to make people happy, and Katsuki wanted to be the best hero ever! If he couldn’t make dumb Izuku happy, then how bad of a hero would he be? Obviously he had had to fix this.

 

Maybe, just maybe, Katsuki missed his friend’s touches too. 

 

After asking around on the playground, he managed to find a solution. There was a girl who was a year older than him whose mother married people. Touching someone was fine if they were married to you, so Katsuki had asked the girl to marry him and Izuku. She agreed, but he had to get everything ready first.

 

The rings were made by a boy with a flower growing quirk. Katsuki had some of the kids who followed him around spread the word on the playground so people would come because you had to have people watching. The boy with the flower quirk also helped set up an arch with flowers because you needed that too. With all that ready, he took the rings, found Izuku, got down on one knee, and told him they were getting married. 

 

Okay, maybe the girl had said you were supposed to ask, but Katsuki already knew he’d agree. It definitely didn’t make his heart flutter when Izuku jumped up and down and said yes to the question Katsuki didn’t ask. He shouldn’t need to ask Izuku anything, they knew each other too well for that. 

 

The rules said that Izuku’s dad was supposed to walk him down the aisle to give him to Katsuki. They couldn’t do that since Izuku’s dad had been gone for ages, and Katsuki didn’t want someone to give Izuku to him. Izuku was his because he said so, no other reasons allowed. 

 

So instead, Katsuki walked with Izuku down the aisle. All their classmates and two of their teachers were watching, the two teachers Katsuki liked. 

 

The girl married them, Katsuki made a vow to protect Izuku against any threat. Izuku promised to stay by his side no matter what. They kissed, exchanged flower rings, and that was that.

 

He should’ve known better than to make a promise like that.




Izuku touched him a lot more after that. Katsuki touched him too. Before he usually only tolerated Izuku’s touches, letting the other hug him or snuggle against him with a huff. Now he hugged him back, held his hand, and stroked his hand through his messy hair.

 

Summer came, and Izuku started feeling sick.

 

At first it was just feeling a bit dizzy. Then he started falling down. He got headaches. 

 

Katsuki tried to help him, tried to hug him more, tried to hold his hand just like Izuku liked, but nothing helped.

 

A week passed and Izuku had to go to the hospital.

 

Katsuki stayed by his side, even as he heard the doctors whispering about unknown causes. Low blood pressure. Weakness. Nausea. He held onto Izuku’s hand even as he got worse and worse. 

 

Even as he heard whispers of not going to make it. 

 

It was Katsuki’s mother who made the call, when Izuku couldn’t even open his eyes anymore. She picked Katsuki up and pulled him away from the bedside. Desperately he hit and kicked and fought to get back to Izuku’s bedside, but his mother wouldn’t listen. Too young she said, too young to see someone die.

 

He tried to escape from the house twice to get back to the hospital. Why wouldn’t his parents listen? He’d promised Izuku he’d be there, promised to protect him! How could they make him leave?

 

Katsuki cried himself to sleep that night, clutching his ring and wishing he hadn’t said till death do us part. He didn’t want death to take Izuku away from him. Nothing should be able to take Izuku from him. 

 

The next morning his mom got a phone call from Auntie Inko, and she cried happy tears. She told him Izuku had made it through the night and was doing much better. Whatever it was seemed to be gone.

 

He was allowed to go back to the hospital that day, and he went straight to Izuku’s side. 

 

Izuku cried when he saw Katsuki again, clutching his hands and begging him not to leave again. It had been so scary without him there. Katsuki held him tight and renewed his promise.

 

As the hours wore on, Izuku got worse again. Again, when Izuku couldn’t respond anymore, his mother pulled him away.

 

Again, he cried himself to sleep. 

 

Again, in the morning, they got a wonderful, wonderful, phone call. 

 

The third time the cycle repeated, the doctors got suspicious. They started talking about the day night cycle. About things coming in and out of rooms. Environmental toxins. The term triggered a fuzzy memory, pushed at the back of Katsuki’s mind. 

 

He knew that term from somewhere.

 

Where?

 

Izuku was moved into a clean room. Katsuki wasn’t allowed to see him. Nobody was. 

 

This time Katsuki didn’t fight it. Now a fear had buried itself deep in his stomach. 

 

He went to the local library, and picked up a book he had read many times since he got his quirk. It was about mining, but Katsuki had read it for the parts on detonation. On the safe use of nitroglycerin. The other sections he skimmed past usually, but not today.

 

Today he went and read all the warnings for nitroglycerin more carefully.

 

Highly unstable. Katsuki was careful with it, with his movements, with exploding things.

 

Highly Flammable. Katsuki always made sure his hands were clean before he used the stove. 

 

Highly Toxic. 

 

The words had never mattered much to him. He wasn’t sick, so clearly his nitroglycerin must be different. 

 

The symptoms were listed just below the warning.

Dizziness. Headaches. Low blood pressure. Fainting. 

 

Potentially fatal even at low exposure. 



The doctors had been confused. No condition had explained all of Izuku’s symptoms. Now that Katsuki thought about it, he hadn’t used his quirk in the hospital. Obviously. He would be kicked out. The doctors had been told Izuku didn’t have his quirk yet, maybe they didn’t know Katsuki had one either. His palms had still been sweaty though. They had been all summer. 

 

He slammed the book shut, and ran out of the library. As fast as he could go, he ran back to his house. 

 

Neither of his parents were there, they were with Auntie Inko trying to help her cope. Katsuki raced into his dad’s office, into the filing cabinet where his dad kept everything important.

 

Medical records were clearly labeled, Katsuki pulled out the most recent addition. 

 

Most of the quirk report talked about controlling explosions. Avoiding heat. Dealing with nitroglycerin in the laundry. Nightmares. 

 

There was one little note at the bottom, buried under everything else. 

 

Possible toxicity, be cautious about touch when sweating. 

 

His body felt numb. 

 

Katsuki put the report back in the file, closed the drawer, and left the office as he’d found it. 




Three days later, Izuku was deemed all better and good to go home. The doctors blamed the sickness on flowers that had been brought in for the child he’d shared a room with. 

 

Katsuki knew the truth, but he didn’t say anything. Couldn’t bring himself to. Couldn’t let them know he was almost a murderer. They’d put him in jail for sure, lock him away and never let him see anyone again. He’d be a villain. 

 

Despite his recent sickness, Izuku was happy as ever. He tried to hug Katsuki, tried to hold his hand, tried to snuggle him. Before it had made Katsuki feel warm. Now it made him sick to his stomach.



Hadn’t he made a promise? A promise to protect Izuku no matter what?



Heroes always kept their promises. 

 

So Katsuki did. 

 

He protected Izuku from the villain who almost killed him. Who nearly stole his life three times. Katsuki himself. 

 

After that day, he didn’t let Izuku touch him. He’d use his explosions to keep him away if it came down to it. 

 

Green eyes looked betrayed, but that was okay because they were still open. 

 

Anything to stop himself from killing the one he loved.

 

Other people stopped touching him entirely. Even his parents learned to leave him alone. Dangerous. A ticking time bomb. Explosive. 

 

That was what they whispered.

 

People were afraid of him. It was for the wrong reason, but Katsuki didn’t care. As long as they didn’t touch him they were safe. Everyone was safe from him.

 

Everyone but one.

 

Against common sense, against reason, against Katsuki’s will, Izuku still reached for him. 

 

No matter how hard Katsuki pushed him away. No matter how mean Katsuki was to him. No matter what Katsuki tried. 

 

Izuku kept reaching out for him, hand outstretched, eyes so trusting and innocent. Even when Katsuki wouldn’t take his hand, he still stayed by his side, walking as close as he could. Pushing him away only worked for a short time, he was always back. So Katsuki kept pushing, and Izuku kept reaching. 

 

Katsuki kept his promise.

 

Izuku did too. 

 

Day after day. Place after place. Year after year. 



Until finally,

 

One of them found the words to say,

 

The promise the other made,

 

Wasn’t a promise they wanted anymore,

 

And they learned,

 

Keeping a promise isn’t always the important part,

 

Sometimes the important part,

 

Is letting go,

 

So you can make new ones instead. 

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