"Blinded by his arrogance,
he failed to see the truth..."
-Oshiego (Blood Omen)
Muscular was, well, muscular. It was kind of implied in the name; how much so, though, that was something else. Towering masses of pure muscle (or an awful lot of myocyte cells, if you prefer that. Perhaps that form of his was just a very, very accelerated form of myogenesis - the formation of muscular tissue - that just discarded the whole skin part?) that were very red and fleshy. Reasonable considering the no skin part.
While that, in particular, was somewhat traumatizing - the globs of flesh twisted and seized with each and every movement - he could forgo his momentary discomfort considering the sheer advantages Muscular lacking the largest organ in the body could bring. The skin is oh so very important; it stops germs, chemicals, and other diseases at the 'doorstep' of your body, it regulates your body temperature and protects your other organs. Most importantly, though, is the fact that the muscle is just exposed like that.
He wasn't entirely sure if normal lightning would have such trouble, but the skin was a major detriment to him. On top of having to deal with a ridiculous amount of resistance - since air is a bitch when it comes to lightning - he couldn't go to the very extremes of his ability. That was also the reason why it was (virtually) impossible for him to mess with other people's heads with distance encumbering him. Regardless, this situation is special because, despite the distance, something else is making up for it rather nicely.
The whole body is controlled by the nervous system, which is, in turn, ruled by electricity. Forcing Muscular to do the splits was the least of things that he could do. He could straight-up force him into a cardiac arrest. And Muscular's quirk had to be attached to his body, despite the way they just kinda... popped out of thin air. No matter how many globs of flesh you have, if it isn't attached to the body, it's useless.
Thus, no connection = no super strength, and since he has super strength, there must be a connection.
In other words...
'He's completely at my mercy. Which isn't at an all-time high today.'
The 'fight' went something like this: He released a single bolt of lightning, and Muscular was now his lab rat-, ahem, his successfully defeated enemy. If he chose to experiment on a few things, well, Muscular lost. Considering that this particular fight was to the death, he felt he was being pretty lenient. He started off with his triceps and biceps, observing the extent of their maneuverability. He could easily do the splits, and his control extended to even forcing his arms to dislocate themselves when reaching something. He played around a bit with the manifested muscles and did a few minor experiments. If he could pry them off, the density, blood samples, etc.
He felt like he had vaguely crossed a line when he forced him to start dancing to the beat of Gangman Style. Just slightly.
He let him drop to the ground after that, a bit too disturbed at the sight of a grown man doing dance moves that only skinny teenage girls had any right to do. He somewhat cursed his vaguely - but not really - encyclopedic memory. The dance just had a way of burning itself in your mind, more so than it had any right to. It was a symptom supposedly shared by many other people, considering that that accursed footage had more people viewing it than the United States, China, and India's population combined.
It had even survived the Dark Ages-...
'I'm getting a little off-topic here.'
But the utter look of humiliation and fear was so worth it-...
'Just. Stop. Don't think about it anymore, me. You'll just remember that atrocious dance... Too late.'
He slunk down to the ground (far away from Muscular, he wasn't braindead yet) and sighed. This forbidden move was a double-edged sword, indeed. Although his humiliation was lesser compared to Muscular, it wasn't that much better. Ugh. (Still, he heavily preferred this method instead of the more... extreme variants. It was stupid and foolish, but it was better than becoming overcome with rage and using more permeant methods. He didn't want to kill someone, especially when it was because he was angry. He knew in his gut that he couldn't come back from that.)
He sharpened to attention at the distant pitter-patter of footsteps rapidly approaching the area as he stood up from his place on the ground.
It was... the kid?
'...I thought he was a bit smarter than this, to be honest.'
He just stood there, frozen, like the world had been tilted a few degrees off its axis.
"W-Wha... How? Y-You, beat him?!"
"Yep. Did you not believe me when I said I could?"
That seemed to make the boy a little embarrassed, but it quickly dissipated. Either his natural personality was just headstrong, or it didn't have enough 'ummph' to really make a difference. He started leaning towards the first option when the boy opened his mouth and talked.
"Well... Not really."
His eyes twitched.
"Ouch. Thanks for the vote of confidence, kid."
He sighed, and his eyes regained their sharpness, like a legendary sword unearthed from ancient ruins. He really didn't care about the little brat's snarky attitude, but he was putting himself at severe risk. He had no choice but to put his serious face on, or else he wouldn't realize the danger he was just about to put himself in. Defeating Muscular by himself, and defeating him with a kid behind him were two different things.
He really couldn't make any guarantees.
"Kid, why did you come back when I specifically told you not to? If what you thought was happening really happened, then I wouldn't have been able to do anything if he suddenly started to attack you. He's way above both of us in terms of physical speed and attack power. A single flick would leave you as paste on the ground. That's why I made you leave in the first place; I have ways of fighting back that you don't."
It looked like the kid had at least listened, but his next words proved that he hadn't really comprehended.
(He really couldn't get mad anyway. His heart was breaking further.)
"...I couldn't let you fight him alone. He-... He's really dangerous, and he... killed my mama and papa. So... I had to do something! I wouldn't, couldn't let someone else get hurt! I know that it was stupid and that I'd probably just be a burden, but-! I just..."
Muscular's body made a small sound, barely noticeable, but Deku had been on high alert the entire time. With a downward pull, his entire body was flung into the ground with tremendous force, little miniature shock ways tunneling through the ground. He let out a loud groan, but Deku didn't feel any sympathy. He couldn't really say anything about the boy's parents, but it was a fact that he was... alone, now.
He didn't doubt that there was some kind of adoption or foster care system set-up, but no-one ever really recovers from the loss of a parent, especially at a young age. It was just one among many reasons why Deku was infuriated with Muscular, but it was nearing the topic in record time. (He would know, with his bastard of a father who just... left one day. He had never really liked the man, but there was always a part of him that had felt insecure and unworthy because of him. It wasn't the kid's situation - who he really needed to get the name of - but it was close enough.)
"Don't move, Muscular. Or do you want to play Marionette some more?"
The look of horror on his face was almost funny, but it was hard to laugh at a murderer. Then horror turned into rage. Typical. And incredibly stupid. What good is it to antagonize your captors? He didn't think he would ever understand. It was better to bide your time and wait. Showing off your true motives was the epitome of stupid, but a lot of people did it. A lot.
"You little piece of-!"
He let a bolt of lightning trace his body, taking extra care to stimulate select nerves along the way.
"Don't swear in front of children. Also, you should know by now that I don't make empty threats, Muscular. Do you really want me to go that far? It's best if you let go of your rage; you'll just suffer more for it. Surely you're more pragmatic than that? Think about reality, friend."
He shut his mouth without another peep and played dead.
The kid backed away, a very suspicious and slightly traumatized look on his face.
"...What did you do to him?"
His face lit up with grim satisfaction.
"Nothing more than he deserved. Oh, and what's your name, kid?"
He just kinda stared at him with a weird look in his eye. He made a 'come on' gesture with his hands, and the kid sighed.
"...Kota. Kota Izumi. What's yours?"
He smiled.
"You can call me Deku."