The harsh brightness of the sun, coupled with the beeping of his annoying alarm clock, greeted Bakugo Katsuki like a kick to his teeth. He hissed as he turned to his side, burying his head further into his favorite (and only) pillow in a desperate attempt to get back to sleep. This, of course, didn't stop the beeping that kept getting louder and louder in his ears, which made him more and more pissed until he slammed his fist on his alarm clock resting on his night table. The blonde groaned out in relief as the beeping slowly ebbed away, almost as if it the alarm was losing its own life; yet still his building headache didn't subside, which made his next realization that much more horrible:

School.

A place he tolerated at best and loathed at worst. It was just so fucking boring and made him feel like everyone else. He already knew that whatever they were droning on about wasn't going to mean shit when he was staring down a weak-ass villain on the street, so what the hell was the point?

A sigh of great reluctance escaped his parched lips as Bakugo further roused from his slumber. He sat up as he tiredly swung his legs to the edge of his bed, stretching out his limbs like a cat as he groaned in satisfaction. The blonde rubbed the sleep out of his eyes while he tasted his god awful morning breath. He should probably brush his teeth soon, especially with all the food he had last night...

It finally hit him. Immediately Bakugo began feeling up all around his body to make sure yesterday wasn't just a dream. He scrambled out of bed and over to his closet, opening the side that had his full length mirror.

The young man in the mirror looked as if a divine hand sculpted each and every part of his body with purpose and thought. His arms felt jacked and looked bigger, but not to an extent where it looked unbelievable or gross. His stomach (which used to stubbornly hold onto the baby fat he'd been meaning to get rid of) was now replaced by a perfectly chiseled six-pack; sharp enough to cut glass and firm enough to most definitely take a Quirk-enhanced punch. And if Bakugo thought his thighs (and his legs in general) were fit before, they were nothing compared to the toned and lean work of art he had now acquired. To say this was a confidence (and ego) boost would be a massive understatement, and the blond wanted to flaunt his new body so damn much.

But he knew that it would be a little difficult to explain this to anyone out of the blue. The extras at school would grovel and shower him in praise (of course), but his parents would definitely question the sudden changes in his physique like the assholes they were. Asking him stupid questions like if he was on steroids, as if he'd need any outside help to be the best.

Bakugo ignored the thought in the back of his mind about the "passenger" who was responsible for this change.

Katsuki, still impressed and in awe of his new body, flexed his new form like a bodybuilder in front of the mirror, wondering how the hell Slimefuck managed to do all this cool ass shit in the span of one night.

"Did I do okay?" came the sudden quiet voice that seemed to emanate from the nape of the blonde's neck. The voice was filled with timidity and something else that he couldn't yet identify. "I hope I didn't go overboard, but I couldn't ask you as you were, well, sleeping."

In equal parts dread and sick curiosity, the host reached behind his neck and felt the pair of gooey lips that questioned him, tugging and prodding at them slightly. He shivered a bit at the coolness of them, stretching and practically behaving exactly like Midoriya's unwanted and "outlawed" moniker. This whole situation unnerved him a bit, on account of how much this reminded him of those old 20th century alien horror movies he and his family would watch ages ago.

But he couldn't say that, at least not in a way that'd make the slimefuck end the deal.

"I wouldn't say it's perfect , but it's a good first attempt, Slimefuck." Ignoring the way the pair of lips turned into a frown, Bakugo began to put on the last piece of his uniform. While the pants that he put on earlier were a tight fit and a bit snug in an undesirable place, he could ignore that until he got a bigger uniform. What he couldn't ignore, however, was the fact that his blazer wouldn't even go past his unflexed biceps. "Oi, my uniform doesn't fit anymore, Slimefuck," he called out, not really caring about Rule #4 at the moment (or for the future, if he was being honest).

Like he predicted, "Midoriya" instantly removed his slimy lips from the nape of Bakugo's neck and popped his gooey head out of the blond's stomach. "Kac-Bakugo! Did you forget Rule #4 already?! the slime despaired, sporting a comically dramatic frown. "I ignored it the first time because I thought you were tired, but come on!"

"Lower your voice, you freaking chestburster!" Bakugo whisper-shouted, clamping his hand down on his partner's cool lips. "You're gonna wake up my parents, you dumbass," he warned before slowly removing his hand. "Now can you fix this or not, damnit?!"

"I...don't know?" Midoriya answered, somehow conveying with his face alone that he was shrugging. "I mean, if it was a limb that I just made for you then yes."

"And how is this different from yesterday when you made that freaky foot-hand?" Katsuki countered, raising an eyebrow in suspicion.

"Uh, well...let me put it this way: If I made you an extra arm and then I detached from your body completely, the slime that made up the new limb would also come with me. And it would also be very painful," Izuku added, trying to forget the dog he had met so long ago when he was out on the streets. "But if I took the time to give you, say, muscle mass and your body got used to it, my slime would be converted to your skin, tissue, nerves and such," the slime finished in a teaching tone, relishing the small moment of being in his element (Quirk explanation).

Bakugo frowned at his partner's nerdy response before scoffing in agitation, throwing the blazer of his uniform to the ground. "So you can't fix it? Fan-fucking-tastic."

Izuku didn't like that. He spent the whole night studying to try to be useful to the one and only person to give a damn about him. His host, who had given him hope and a home, who appreciated his slimy abilities and told him that he could be a hero; Midoriya repaid that kindness by not even knowing such a simple answer to such a simple question. "Why can't I just be useful? I need to be useful, or else...or else he might leave me," Izuku thought glumly as he retracted his head back inside his host. "At this rate I'm as useful as that stupid foot-hand I gave him yesterday...wait-"

A lightbulb went off inside his head, an epiphany when he needed it most: All this time, Midoriya has always given an extra limb or whatever and then taken it away. Can't he just do it in reverse?

Midoriya tried to visualize that. Normally whenever he creates an extra limb he finds an area to work off of. He sends the required slime to the area and then manipulates it to (usually) copy the host's DNA blueprints to make an exact replica. And then when the extra limb has served its purpose, Izuku just destroys all his hard work by telling his slime to return back to normal. But if he lets the extra limb settle in for too long the slime becomes a genuine part of the body, making it impossible to remove.

Or so he thought before. If he could, perhaps, "eat" an area of his host...wouldn't that mean he would have an area to work off of?

Before voicing his newest idea Midoriya realized that, while he wasn't paying attention, Bakugo had wandered into the bathroom (still shirtless). He was angrily brushing his teeth as if the bacteria there to help/harm him had personally offended him, all the while glaring at his reflection in his rage. Amazingly he had not drawn blood at all during his harsh and unrelenting force that he applied to his gums.

If the young greenette had a spine he might've admitted that those angry lava-colored eyes scared him, filled him with the sense that he was going to die if he pissed him off one more time. No warmth, no comfort, and especially not mirth shone in Bakugo's eyes.

Midoriya, after much internal debate to himself, gulped (metaphorically) as he decided to sprout a tiny pair of lips inside the left ear of Bakugo. After temporarily reorganizing the blood flow towards his host's brain, connecting himself to the lungs, and giving himself a tiny set of vocal cords Izuku decided to say the first thing on his mind: "I, uh, think I figured out a solution to our...your problem."

The blonde paused mid-swig as he was about to pour the mint-flavored mouthwash into his mouth. A moment after Katsuki spat out the arctic blue liquid he asked aloud while looking at himself in the mirror, "You can speak inside my fucking head?"

"Not quite, I haven't figured that one out yet."

"Knowing that you're practically incapable of sarcasm makes that all the more terrifying, you god damn nerd," Bakugo muttered before proceeding to splash water on his face.

Sadly he wasn't dreaming.

Resigning to his fate, the blonde walked back into his tidy room and picked up his black blazer that he haphazardly threw to the ground. He held it in both of his hands before warning his partner, "It better not hurt, Slimef-...Midoriya."

With a nonexistent smile at hearing his real name, Izuku turned off the feeling in his host's arms. The slimebiote slowly allowed some of his body to ooze out of Kacchan's pores, specifically right on top of his biceps. The former waited for a complaint, to be told to stop. When he didn't get one, Midoriya commanded his slime to cover the biceps and then rapidly digest them until nothing was left except for bone. Ignoring the "horrified/amazed that it doesn't hurt" look his host was giving him, Midoriya then visualized the muscles, tendons and nerves. How interconnected they were, how each part had a small (but important) part to play, all coexisting in the same general area. With those thoughts in mind, Midoriya rebuilt the biceps from the ground up until it was finally finished.

It was still big, but not like before. Bakugo tentatively squeezed each of his biceps one at a time, amazed that the entire conversion took less than thirty seconds. It was horrifying, seeing as how he literally watched himself get rapidly digested and rebuilt, but it only solidified to him that making this partnership was worth it. Plus it was a first attempt that didn't fail spectacularly, so bonus points for the success.

Which made the next part even harder.

If there's one thing Bakugo remembers from all the times he got grounded by his parents (though it was usually his mom dishing out the punishment) it was that he wasn't "nice" enough. Which was bullshit but they didn't give a flying fuck. It didn't matter what time it was or wherever they were, if his mom thought he was being an asshole she'd straighten him out with a huge shouting match that could be heard several blocks away.

One time, after a particularly long tongue-lashing, his mom said something to him that stuck with him, so to speak.

"Katsuki," Mitsuki quietly said as she kneeled down to be eye-level with her only son. He was sitting down in the school nurse's office, his clothes scuffled and a couple of scratches littering his arms. He looked pissed to be there as he sniffled his nose, trying his best to be "tough like All Might", but as his mother she knew he was holding in his tears. "You know I love you, but you can't go around beating up kids at lunch who make you angry-" "Nobody wanted me at their table, Mom! I'm smarter and more cooler than all of them, so why are they being assholes?!" Katsuki angrily shouted, having a mini tantrum on the seat. A thump to the top of his head later and the young mother sighed in exasperation as her Katsuki rubbed his head in slight pain. The matriarch silently wished her son didn't inherent her temperament, as she didn't stop being an asshole to others until she met her first true friend near the end of middle school. At the time she treated her best friend like shit, but the years mellowed her out over time. Mitsuki lightly shook her head side to side before she went down memory line again, knowing she could cry and mourn for her best friend later after she dealt with her misguided and distraught son. "Katsuki, would you rather be All Might or Endeavor?" she asked innocently, already knowing the answer. The youngest Bakugo rolled his eyes, questioning whether his mother was the most stupidest person in the world. "All Might, of course! That's a dumb question, everyone wants to be All Might, he's number one! Nobody would want to be stupid mean Endeavor!" Katsuki childishly explained in his fervor. "But then why do you act like 'stupid mean Endeavor', sweetie?"

Bakugo shook himself out of his past and with surprisingly little effort gave a genuine smile, "Good job, Midori," he praised, ignoring how his skin developed goosebumps yet again. "Now shut the fuck up before my parents throw me into the loony bin for talking to myself."

With a needless shooing away gesture he proceeded to throw on his black blazer, humming in satisfaction that his uniform fitted him once again. Katsuki spared a quick glance of the time displayed on his alarm clock, its dim and flickering lights telling him he was late to school. Grinding his teeth in annoyance, he rushed out of his room with his bag (and partner) in tow, slamming the doors behind them as he rushed down the street in the direction of his school.

In his haste neither Bakugo nor Midoriya realized there was now a fist-sized imprint on the alarm clock, recently made by the former that very morning.