Prompt fill (sort of) for AO3 user 'Infestation', who requested- 'MizuSei or MizuSly, scars on pale skin vs scars on dark skin.'
I went really off prompt with this, seeing as I didn't mention Mizuki's scars at all, so it's a very loose prompt fill :)

Trigger warning- This fic mentions and centres around self-harm by burning, read with caution.


He hadn't noticed right away, the series of small, perfectly circular burns that spotted the pale skin of his inner arm and wrist, concealing the bright blue veins that lay just below the surface of the flesh. The first time had been a trial by fire, having a casual smoke in his bar, ashtray in front of them so they wouldn't make a mess. He had just ground his own cigarette out, sighing comfortably and sitting back, watching as the blue haired male finished his off, smoking right down to the filter, not wanting to waste a single drag despite of the fact that he didn't fund his habit. He turned round to get another drink, something slightly weaker this time as the sake he had been drinking before burnt his throat. Breath catching in his lungs as he noticed what was happening, reaching out a hand to slap slim fingers away from a ruined arm, earning a hiss and a scowl for his efforts.
"What the fuck are you doing?" He'd cried, staring at the new burn with horrified eyes, not sure if he was more unnerved by the action itself, or by the completely expressionless look he'd had as he pressed the red-hot cigarette against his arm, extinguishing it against his skin. There was a smell of burnt flesh that made Mizuki feel sick, alcohol in his stomach churning unpleasantly and making him want to throw up.
"Putting out my fag." Sly had replied calmly, reaching for the packet that lay on the bar counter between them and helping himself to a new one, ignoring the fact they were actually Mizuki's. He lit it quickly enough, taking another drag and shooting the stunned bartender a glare. "What?"
"What do you think ashtrays are for!" Mizuki had found his voice, gesturing to the aforementioned ashtray with fingers that trembled.
There was a pause as Sly just stared at him, before he finally answered, voice flat and casual, as if nothing out of the ordinary had just happened. "Ash I guess."
"And butts. They're meant to have cigarettes put out on them, not your arm!"
"Why do you care? It's not like it's your arm." Sly retorted, taking a long drag that made ash tumble from the lit tip to land on his jacket, white smearing across the black.
"That doesn't matter! You shouldn't be hurting yourself at all, I'd rather you put them out on the fucking bar than your arm!"
"My body, I'll do what I want." Sly lied, knowing full well this wasn't his body at all, not technically. It was Aoba's, that stupid cry-baby with amber eyes and a loving heart. It was Slys while he could keep Aoba at bay, which was easy at the moment, but he knew if wouldn't stay like that and the least he could do was leave him with some reminders of his other self. Restraint was completely silent these days, no doubt just talking to Aoba somewhere in the recesses of his broken mind and scheming against him. His Rhyme, casual sex and substance abuse might not leave lasting marks on Aoba, unless he got an STD or something, but this did. This meant the blue haired boy could never forget what he had done, what a part of him had done and was capable of.
Mizuki sighed exasperatedly, "you don't get it do you?"
"What's there to get?" Sly frowned, wondering how Mizuki would react if he showed him the neatly arranged lines slicing down his thighs and the faded marks on his ribs from blunt nails dragging across skin.
"It's.. you," he made a noise similar to a groan, words trailing off weakly. "Look, you can't just hurt yourself, how long have you been doing this for?"
Sly made a great show of working this out, raising his fingers and mouthing unreadable words, muttering softly under his breath. "Three years." He announced a second later, that was a rough number, he'd been doing it since he could first remember getting the body. The shock of being in control, the number of things around him he desired, people, drugs, food, cigarettes. The first drag hurt like hell, smoke invading his previously undamaged lungs and making him cough, but he continued, the faint nicotine buzz in the back of his head encouraging him. It was like being tipsy, not that he'd got round to experiencing it yet, but he imagined that was what it felt like. He took another drag, too deep, too much, too fast. It hurt. Pain was something he hadn't experienced either, he'd been locked up inside Aoba's mind, not even as a tangible form but as a voice. He could see through Aoba's eyes, but he couldn't feel. He'd been there, watching as Aoba tripped and cut his knee, blood trickling down his leg. Heard the cry of pain and the following sobs, seen the wince as the cut was cleaned, but never felt it. Pain, he soon realised, he craved as much as anything else, possibly more. Now he had it in his mind, he needed it, now. Patience wasn't his strong point, he wanted it to hurt and he wanted it now, not realising the cigarette between his fingers was burning down until it singed his fingers, earning a soft gasp. It hurt, and god did it hurt good. The box in his pocket became his saviour that day, smoking his way through all of them until he coughed up greenish goo and his throat roared with every drag. The skin of his arms was pale and unmarked, perfect to be decorated with a patchwork of perfect circular burns. The pain made him grit his teeth and hiss, dropping the crushed filter to the ground with a pained chuckle, voice breathy with lust as searing heat ran through his veins. After that, the pain lessened, he supposed he grew used to it, it just became habit to extinguish cigarettes on his arm, the dull throb it created pleasurable for mere seconds before fading. Smoking too no longer hurt, nicotine buzz gone, he was straight up addicted now, smoking a box or two a day, financed by the Yakuza twins, stolen by him or given by Mizuki.
"Jesus Sly." Mizuki's voice was disbelieving and more than a little disapproving as he stared at him with olive eyes, head shaking slowly. "You're so fucked up."
A casual shrug and another cigarette pressed to mutilated flesh. "I know."