[MHA Characters are test subjects in a secret, underground lab (part seven) Tetsutetsu is badly injured during an experimentation session and has to cope with the after effects.]

It was only meant to be a standard experimentation session, the day the accident occurred during the thirteenth year of sector one's research. It was a birthday, or the day after one at least. On each birthday, the scientists in 1A did their annual quirk examinations where they tested the limits of the child's ability and compared the results to the previous year's examination. None of the children looked forward to their birthdays.

Since subjects 16 and 17, Eijirou and Tetsutetsu Kirishima, shared a birthday, Tetsutetsu, the younger twin by eleven minutes, always got his examination done the day after, so the day after his birthday a newly thirteen-year-old Tetsutetsu was escorted to the experimentation ward to spend the day pushing his quirk to the absolute limit as he had done twelve times before. His quirk hadn't improved much over the years. No matter how often you polish it, or how many times you remold it, steel will never be more than steel.

Steel softened and melted at high temperatures. Steel got weaker and more brittle in the cold. Steel cracked and dented under immense force. If you hit it hard enough, or often enough, steel broke. But not as easily as skin and bones. It didn't tear like flesh and muscle and sinew tore. A shoulder being ripped from its socket made a very different sound than the heavy clang of metal on metal. Bones being completely pulverized by concrete didn't feel anything like a steel-skinned back slamming against a wall.

The smell was the same. Blood leaking out and pooling on the floor; sweat and iron slowly oxygenating into rust. Metallic and sickening.

With skin that hardened into steel, one might think that Tetsutetsu wasn't used to pain, but they would be wrong. Steel wasn't strong enough. It couldn't protect him from what happened in the experimentation ward that day, when he failed. He thought he was going to bleed out and die, but he didn't. When he finally woke up, and they sent him back to sector 1C, the habitation ward, he wished he had.

"Holy shit Tetsu! What happened to you bro?" Eijirou was in front of him as soon as he walked in, scarlet eyes full of worry, eyebrows drawn together, mouth open ever so slightly, so the just tips of his pointed teeth could be seen. "You were gone for three days... your arm..." Eijirou reached out hesitantly, but didn't touch his brother.

Tetsutetsu's left arm was completely gone. The stub of the shoulder was wrapped in fresh bandages, still healing. The others were closing in as well, wanting to see their injured friend. Tetsutetsu looked down in shame. He couldn't meet their eyes.

"It got crushed during the examination," he managed to say, choking on his words. He wasn't a crier, but tears threatened to spill over his thick eyelashes nonetheless. It still hurt. He had only been given minor pain relievers so they wouldn't impair his ability to think or focus on lessons, and he was in so much pain, and in more than just his shoulder. He could still feel the phantom pains like thousands of tiny needles stabbing up and down his entire arm, even though the arm wasn't there anymore. "They're already working on making me a bionic replacement."

"Can I..."

Tetsutetsu looked up to see Eijirou's arms spread, offering a hug. He stepped into his brother's careful embrace, wrapping his arm around Eijirou's neck. His arm. Singular. Sensing that this was a personal moment, the other kids gave the brothers some space. Tetsutetsu finally let himself cry, but only for a few moments, not for long.

The injury affected every facet of Tetsutetsu's life. He never imagined what it would be like to lose a limb, never wanted to think about what might happen to him if he became 'damaged goods' in the eyes of the scientists. Everything was harder with one arm. Whenever he wrote anything, the paper slid under his pencil and he couldn't hold it still. He typed at less than half the speed he'd been able to before. He could barely dress himself, and since he couldn't sleep in his pod with a wounded shoulder, he had to sleep in the experimentation ward. Fully aware of everything and unused to sleeping without sensory deprivation in the place of his nightmares, it was a wonder he slept at all.

It took nearly a month for the scientists in 1A to create a new arm for him that was up to their standards, and it took over forty hours to integrate the bionic arm's sensory and control systems with Tetsutetsu's nervous system. They installed a plate in what was left was left of his shoulder to attach the arm to, fused it to his skin and bones so it could never be removed.

The arm was carbon reinforced titanium with integrated calcium, and perovskite veins. That's what the scientists told him, anyway, he was pretty sure they put in other compounds and mechanisms and whatever else they saw fit. It was seventy-eight percent stronger than standard steel, and half the weight. It was stronger than steel. It was more powerful than what it was replacing.

It moved just like the old arm, in the same ways, and according to how his brain told it to, but there was a lag of about a fifth of a second. It was slow. It didn't feel things the same way his real arm did. It sent sensory signals and impulses to his brain, but they were rudimentary: hard, soft, smooth, rough. It couldn't sense temperature at all, and it wasn't very good at texture either, only recognizing basic markers.

They tested it. He could recognize the difference between fabric and paper, but not between denim and leather, or cardstock and parchment. It also couldn't send pain signals. They tried it, but it seemed like the brain wouldn't accept pain signals from the fake arm, it just threw them out. That could have been a good thing, but it was overshadowed by the phantom pains Tetsutetsu still felt, like dipping his arm in hot lava. Eventually those pains would begin to fade, but never completely.

For the first six months, Tetsutetsu was required to use the new arm as much as possible, even for things he never used his left arm for before like writing and using chopsticks, so that he could use it properly. It was terrible, especially with the slight lag in its reaction. When he sparred, he learned to have his left arm already up and ready to block, otherwise he'd take a hit in the slightly extended time it took to raise it. When it came to physical training, the arm was as much a hinderance as it was an advantage.

The bionic arm lifted more than twice as much weight as his regular arm, or it could have if the rest of Tetsutetsu's body could handle it. It couldn't. When he turned his skin to steel, he couldn't dream of making it as strong and durable as the prosthetic. Even at full strength, if he pushed himself to the absolute limit, his whole body was weaker than a hunk of metal stuck to his shoulder, made up in a lab over the course of a month. And to top everything off, he was already the weaker twin.

Eijirou wasn't limited to the strength of steel. He could make his skin even harder than Tetsutetsu's new arm, harder than diamonds, probably, though he hadn't gotten there quite yet. The kids in the lab were always compared to each other, that much was obvious by the scoreboards on display in the instruction ward, but Eijirou and Tetsutetsu were compared to each other the most, because they were the only ones who were actually related, and try as he might, he wasn't better than Eijirou at anything.

Eijirou was always top three in athletics. Bakugo had a firm grasp on the top spot, but he and Kendo were constantly fighting for second, their positions changing almost daily as they had been for years, Tetsutetsu was tenth. Last he checked, his brother was ranked ninth for quirks, whereas Tetsutetsu was fifteenth and solidly in the lowest of the three tiers that each category was split into. At least they were both in the bottom tier for academics, but ever since Bakugo started tutoring Eijirou, he'd had a leg up on his brother. They stood at fifteenth and sixteenth, but unlike with Eijirou and Kendo's positions in athletics, Tetsutetsu always lagged just behind.

The arm had to be removed to sleep in the pod. It unlatched when Tetsutetsu needed it to, then the plate on his shoulder that the arm attached to sealed so that the fluid in the pod didn't seep into the wiring or connectors. He was only supposed to remove it to sleep, but Tetsutetsu wore it as little as possible in the habitation ward, 1C. Unless it was essential, he attached it the the electromagnetic mount that had been installed on the side of pod 17. He absolutely hated the thing.

"Hey, Tetsu," Eijirou came to talk to him one day during their free hour. Tetsutetsu had hung up the arm and was doing one handed push-ups, trying to get the rest of his body up to same level as that damned arm, even though he knew it was impossible. "You're not okay, are you?"

"Are any of us?" Tetsutetsu retorted. He'd already lost count of his push-ups, so he didn't really mind the conversation. "Don't suppose you could sit on my back while we talk, could ya? Unweighted push-ups aren't gonna get me anywhere."

"Uh, yeah, sure bro." Tetsutetsu paused long enough for Eijirou to climb on his back and get his balance before starting again, breathing sharply. "You know what I meant though, ever since that accident a few months ago you've been... I don't know man... harder on yourself. You know it's not your fault, right?"

"It's not my fault that I messed up?"

"Not your fault that a bunch of assholes in white lab coats and tinted goggles put you in a position where your arm could get crushed," Eijirou retorted. "Not your fault you're down here in the first place."

"I wish I could see it that way, bro, I really do, but the fact of the matter is, I'm just not strong."

"What are you talking about, bro? You're as strong as steel!"

"Which obviously isn't strong enough!" he barked, and looked over his shoulder to glare at his twin. Eijirou's eyes widened and his mouth snapped shut. "I was never strong enough to beat you, even before my failure lost me a limb, and now I'm not even strong enough to beat my own left arm."

"Is that why you'd rather have one arm than wear it? Because it makes you feel weak?" Tetsutetsu didn't answer, just kept doing push-ups, breathing in through the nose, out through the mouth. "You know, without you, that arm is just a hunk of metal. It can't do anything unless you're wearing it. It just sits there, useless, kinda creepy-looking on its own, really. You are what makes it useful, what makes it worth anything at all. One mistake doesn't make you less manly, and it doesn't make you weak."

"That's easy for you to say," Tetsutetsu grumbled. "You would never have let something like this happen to you." He stopped doing push-ups. "I think you should leave me alone for a while."

Eijirou didn't move for a long moment, then he sighed, got off his brother's back, and left him alone.

[Man, it's like, taxing to write angst out of my own worst nightmares like this. Sorry fellas. Shoutout to blahblahblahkaminari because I wasn't planning on posting this just yet until they demanded a new chapter. Everybody say thank you! Love y'all.

<3 Raaor!]