Izuku The Cipher (Adopted) - (Slow Updates)

The System

Tensei looked at them like they were crazy, even though he already knew that the yellow inventor was downright insane. "It's part of my quirk, dumbass! It's genetic!" he shouted. Bill chuckled darkly, "Oh I already knew that much. I want to know the mechanisms of how they are capable of functioning just like a car. They emit fumes that smell like gasoline, but last I checked, that's not healthy for you humans," Bill explained. "Orange juice. It's fueled by orange juice," he said flatly. Bill was beyond confused by this answer. Orange juice? Why orange juice of all things? And how many different drinks did they test to figure that one out? This also begged to question of whether there were other beverages capable of a similar result.

Tensei had once again tried to worm his way out of the restraints, but they didn't budge. "What the hell is this thing?!" he cried. "A super secret item that only I can wield. Don't bother trying to escape, not even All Might could break out of those," Bill lied with a grin. They tried to hold back their laughter when his eyes widened in fear. The idiot actually bought it. Man, how stupid could this human get?! Bill picked up the hammer and a small saw. "Now stay still, orange lover. I've never done surgery before, so this might hurt," they told him with a sinister grin.

. . .

Tensei was still screaming after the "surgery". The poor excuse of an "amputation" was half-assed and Bill knew it, but they didn't care. They could have removed his arm in a more painless, and frankly easier way, but where was the fun in that? The arm was dragging itself down the wall Tensei was strapped to, slowly and painfully falling apart. Bill placed the saw on the metal table and pulled the arm off bit by bit. First the skin, then the muscle, and then the shattered remains of the bone, each one splattering more fresh warm blood on their white apron. They didn't want their favorite sweater to get blood on it, so they were wearing their plaid undershirt with the sleeves rolled up.

Bill liked it when they got their hands all bloody. It was still a wonder to them how doctors managed to cut open their patients without all the squirming. They decided to rummage through Izuku's memories later to see if he knew any fun facts about the medical field. Bill tightened a rubber strap above the wound to cut off circulation and prevent Tensei from dying of blood loss. They then walked over to the table and grabbed a pair of gloves and began to examine the arm.

They peeled away the outer layer of the skin, making a wet ripping sound as it revealed the muscle fibers. It was then that they noticed an oddly shaped structure attached to the bone. They tapped it with the hammer and it made a metallic 'clang'. The strange noise had piqued their curiosity further and they spent quite a bit of time poking and prodding at the arm. All the while, a numb and barely conscious Tensei watched the yellow blur dance around humming a tune he couldn't quite remember at the time. At some point, Bill had placed a pair of goggles on their face to prevent blood from spraying in their eyes, though he wasn't sure when that happened.

A loud metallic noise startled him awake to see the demon still dancing with a pair of pliers holding a strange object in its teeth. The object was dropped into their hands and they smiled for some unknown reason. Bill had actually discovered a fascinating piece of information to write down. The metal-like object that they had found was actually hardened bone marrow mixed with crystallized tissue to form the illusion of a metallic engine and the fat-like tissue that surrounded it protected him from physical harm on the outer layer of the skin that might be caused by quirk overuse. The item in their hand was actually the engine itself.

Upon further inspection, the hollow tubes that go through the bones and veins are what allow it to function. And as for fuel, orange juice wasn't the only source of fuel after all. It was the main source because it was the most effective, but the engine is actually fuelled by the nutrients inside of the food he eats. And there was a circular organ in the center that, as it turns out, was some sort of second digestive system. It took even the tiniest of nutrients and turned them into an energy that could equal about half a gallon of gasoline, making someone with this kind of quirk never run out of energy, just as long as the user eats a proper meal every day with a healthy snack whenever they can.