The End Class didn't understand Karma and Nagisa's relationship.

Before Karma had arrived, Sugino had curiously asked Nagisa about his old friend. He didn't get many details, and upon Karma's arrival, he understood why.

Karma, in the kindest way possible, was the devil.

The boy's laid-back posture and body language, coupled with his fiery hair, could be excused. There was nothing particularly wrong with them. It was the ever-present wicked smile and glint in his eyes that screamed danger. Even before he blew off one of Korosensei's tentacles, Sugino knew he was trouble.

Which is why he couldn't comprehend how Nagisa and Karma were supposedly old friends. And as Karma integrated himself into their classroom, treating everyone with a cool detachment, Sugino still couldn't understand Nagisa's casual camaraderie toward the boy.

Where Nagisa was soft smiles and hesitance, Karma was smirks and forcefulness. While Nagisa offered quiet insights and conversation, Karma provided lazy taunts and razor-sharp wit. Every detail of the two individuals, down to the colours of their hair, was in complete contrast with the other.

They were polar opposites, and he failed to understand why Nagisa considered him a friend.

"Don't you think Karma-kun is a little... crazy?" Sugino quietly asked Nagisa during training, watching Karma take on Karasuma with reckless abandon.

Nagisa laughed, a sweet, innocent thing, watching Karma with something akin to admiration in his eyes. "Of course, Sugino. He wouldn't be Karma if he were completely sane."

Sugino frowned, watching as a particularly wild strike from Karma cut cleanly through Karasuma's tie in a close dodge. "Well, yes. But are you certain that he is... a good friend for you?"

Because that's what this came down to. Nagisa had been his friend for a while before Karma reappeared in his life. This was the kind-hearted boy who helped him every day after school to practice his throws and supported his dreams of professional baseball. Before Korosensei had even realised Sugino's passion for the sport, Nagisa had been the one to drive him and motivate him.

He didn't want to see Nagisa hurt. He was quite fond of his friend and did not wish to see Karma upsetting or harming him.

Nagisa watched Sugino for a long moment before a gentle smile formed on his lips. "You don't need to worry about me, Sugino. I can handle myself. Karma is a good person."

Sugino regarded Nagisa doubtfully, recalling the red-headed demon that had tormented a professional assassin with little more than a few tubes of wasabi on their holiday.

Nagisa let out another short laugh at his expression. "Perhaps that's not the best way to put it. He may be insane and sadistic, but he is a good friend."

Sugino nodded reluctantly, deciding to trust Nagisa. "Alright."

Karma lost the fight against Karasuma but became the first to be able to brag of landing a blow on their teacher, managing a solid punch to the jaw after being disarmed.

Kayano did not like Karma.

"Heyyy, Nagisa-kun," the red-head drawled. "A new movie is out at the cinemas. You'll come after school?"

Nagisa offered him a bright smile. "Of course, Karma."

Karma leaned back in his chair, kicking his feet up on the desk. "You'll buy the snacks, right?"

Nagisa smiled good-naturedly. "Sure."

Anger shot through Kayano at their interaction, and she glared at Karma's back as he wandered in the direction of the forest, likely intending to skip class.

There was this imbalance in Nagisa and Karma's friendship that deeply troubled her.

The most common, and glaringly obvious instance was in how they addressed each other. Nagisa referred to the red-head as "Karma", as is typical for a friend. Karma, however, called Kayano's friend "Nagisa-kun". And it was that small formality which irked her to no end.

It was oddly representative of their relationship in Kayano's eyes. Nagisa certainly considered Karma a friend, and addressed him as such, but Karma did not view Nagisa in the same light and retained the formality of two strangers.

But instances like these in particular made Kayano's blood boil. Times where Karma blatantly abused the imbalance in their friendship for his own benefit.

"Don't you think that's unfair?" Kayano blurted out before she could stop herself

"What?" Nagisa turned to face her.

"You having to pay for all the food," Kayano pointed out, feeling her cheeks flush red at her thinly veiled accusation. "Shouldn't Karma-kun have to pay equally?"

Nagisa shook his head, smiling. "It doesn't really matter. I'm sure Karma will pay for the tickets."

There it was again. That friendly, familiar address, lacking the formality that Karma used with him.

Kayano wanted to grasp Nagisa's shoulders and shake him until he realised Karma was taking advantage of him. She wished nothing more than for him to regain that formality in referring to Karma.

+++

"Korosensei! Come quick! Nagisa and Karma-kun are trying to kill each other!"

Nakamura raised a delicate eyebrow at that and placed down her book as Korosensei zoomed past her, sending several papers drifting to the floor. Kayano sprinted back outside after him, clearly greatly distressed, and Nakamura found herself following them.

This she had to see.

Indeed, when she slipped outside to join her classmates, Nagisa and Karma were attacking each other with vigour, much to the awe of their onlookers.

As she watched, Nagisa feinted a slash at Karma's left side before narrowly missing a hit at Karma's right arm, as he elegantly dodged both. Nagisa's icy eyes glowed, a dangerous and unfamiliar intent to his clouded gaze. It wasn't a look they'd seen on Nagisa before. Nakamura was always so quick to dismiss the blue-haired boy, with his soft smiles and gentle nature, but there was an undeniable and overwhelming bloodlust to the boy now.

Kayano had been wrong before, Nakamura mused, watching as Karma danced between Nagisa's hits. Karma and Nagisa were not trying to kill each other.

"Nagisa is trying to kill Karma," Sugino breathed, Nakamura silently nodding in agreement.

Even as they watched, Karma let out a laugh. "Is this all you've got, Nagisa-kun?"

It wasn't in Karma's nature to be silent while he fought. He mocked his opponents, getting under their skin and coaxing silly mistakes and blunders from them. Nakamura had studied her friend's style curiously, considering its success. Unfortunately, while it perfectly fit with Karma's nature, she could not claim the same thing.

"Four hundred yen on Karma," she offered with a smirk.

Kayano shot her a scandalised look but Isogai nodded at her in silent agreement.

In her peripheral, Nakamura noted Korosensei freaking out to Karasuma ("They're trying to kill each other! They could get hurt!)

Nakamura smiled in admiration at her red-haired friend, watching as within a blink Karma was suddenly behind Nagisa. "Come on, Nagisa-kun. Are you even trying?"

Nagisa sliced and stabbed at the afterimage of Karma, his movements an incredible whirlwind with flawless technique, but still just behind their red-headed classmate.

Nakamura let out a low whistle at Nagisa's movements. "Impressive," she admitted. She had a thing for boys that knew their way around a knife.

Karma seemed to stand still for almost a whole second, offering his best cocky smirk. "Now, I know you can do better than that, Nagisa-kun."

And with that last word, something seemed to snap into place for Nagisa. He paused, gaze lifting to meet Karma's. This time, Nagisa was the one to smile - not the carefree smile he'd given Takaoka before he'd easily taken him down, but a dangerous curve of the lips to match Karma's smirk. His eyes still seemed to glow with bloodlust, but they were sharper, more focused somehow, and when Nakamura blinked she could swear she saw his shadow transform into a giant serpent, poised to strike.

Karma had noticed the change too, a slow smile creeping across his face. "Come on, Nagisa-kun. Show me what you've got."

And this time when Nagisa attacked, Karma met him blow for blow.

A strike at the head was blocked, only for Karma to send a swift punch for Nagisa's jaw. Nagisa moved at the last second, and kicked out Karma's feet while he was imbalanced. Karma went down but rolled and was back on his feet before Nagisa could press his attack.

"That's more like it, Nagisa-kun," Karma laughed, dodging a wild slash.

Now they were moving too fast for Nakamura to see, and she appreciated Nagisa slightly more. This was the boy who'd taken down Takaoka-sensei and who'd caught the attention of the infamous assassin Lovro.

Karma flung Nagisa over his shoulders, and several of their classmates cried out in alarm as Nagisa went flying. But Nagisa landed in a crouch, tackling Karma in a blur before he could react. Nagisa was on him in less than a second, rubber knife held to his neck. Nobody said anything for a few seconds, just watching Nagisa in awe.

Isogai held out a hand to Nakamura and she cursed before handing him his money.

Karma recovered from his own shock quickly and smirked up at Nagisa. "Hey Nagisa-kun. You planning on letting me up anytime soon?"

The glow quickly faded from Nagisa's eyes as he blushed – blushed, like he hadn't just defeated the best assassin in their class – and stood. Karma grasped his offered arm and Nagisa pulled him up. For a second, they just looked at each both, both slightly out of breath, but smiling.

"Nagisa, that was amazing!" Sugino called, and the trance was broken.

The class swamped them, all talking excitedly. Korosensei was on them too, tilting and rearranging the pair to check frantically for injuries. Karma tried to stab him with one hand while Korosensei worriedly lifted and examined his other.

"You guys are so talented!"

"You'll teach me that move later, right?"

"Nagisa, where'd you learn that?"

Nagisa blushed heavily at all the attention and Karma slung an arm around his shoulders, flicking him in the forehead.

"Ow, Karma!"

"Haven't you all got class to go to?" Karma asked lazily. "English starts soon. Don't want to keep Bitch-sensei waiting."

The class grudgingly settled down and began to trickle indoors, still chatting excitedly. Karma relinquished Nagisa from his hold when Kayano tugged at him, Nagisa shooting the red-head an easy smile as he left.

Soon it was just Nakamura and Karma left. And she'd had a revelation. She understood now, the unlikely friendship between Karma and Nagisa.

"Nagisa is a good assassin," she noted, crossing her arms.

Karma barely shot her a glance. "Yes."

"He makes a good ally," Nakamura continued knowingly. "He's one of the best in the class, and it is beneficial to have him on your side in an assassination."

Now she had Karma's attention, the red-head studying her intensely.

"Did you let him win?" she asked curiously.

Karma scoffed and started to walk away, heading into the woods. Nakamura concluded silently that he did, in fact, let Nagisa win.

(Karma did not.)

+++

It was a dreary day, with grey clouds scattering the skies, when the E Class finally got an insight into Karma and Nagisa's relationship.

Karma wasn't really paying attention as the door to their class slid open, talking to Nakamura (a bright girl, who he could consider calling a friend), but he noticed as everyone fell gradually silent.

Karma turned, meeting the sight of Nagisa, who stared at the ground as he trudged in. Karma's hands clenched into fists at the sight of the boy's hair falling loosely around his shoulders in the way Karma knew Nagisa hated. The other thing that really caught his eyes before his friend quietly sat down, was the large purple bruise decorating his cheek.

"Nagisa?" Sugino questioned in the dead silence of the classroom. Nagisa did not respond.

"Nagisa, are you alright?" Kayano whispered, reaching across the row to touch his arm. Her hand shot back, expression horrified, when Nagisa flinched away.

For a second, there was utter silence as Nagisa continued to stare down at his desk, entire body tensed, until it was broken by the sound of a chair scraping against the floor.

Karma roughly pulled out the chair in front of Nagisa, spinning it around to sit facing him. Karma leaned back in his chair, resting his feet on Nagisa's desk in spite of Kayano's squeak of protest.

"Heyyy, Nagisa-kun, you finish our English assignment?"

Nagisa didn't even twitch but Karma was undeterred.

"I hope so," he continued, twirling a knife in his hand. "You're the only one who gives me any challenge in that class anymore, Nagisa-kun."

There was an underlying tension to Karma's body too, not that any of their classmates noticed. This was normal – Karma could do this any day of the week. Talking Nagisa down like this was practiced. But it didn't change that he wanted to stab the bitch responsible for it.

He caught a glimpse in his peripheral as Kayano started to stand, furious, only for Nakamura to quickly to grab the girl's arm and shove her back down when the green-haired girl seemed intent on attacking him. (He wasn't certain what exactly he'd done to earn her ire but didn't really care. It was unimportant compared to Nagisa.)

"Wait!" He heard Nakamura hiss. "Look at them!"

Karma continued to talk at Nagisa, lazing back in his chair and offering his usual sharp banter, despite it being one-sided. But he was careful to keep repeating Nagisa's name, in almost every second sentence. And with every reiteration of "Nagisa-kun", the blue-haired boy relaxed ever so slightly.

Because Nagisa needed that reminder. His bitch of a mother told her son he was a girl, treated him like a daughter, refusing to let him cut his hair and forcing him into dresses at home. (Karma still remembered that time Nagisa had turned up at his house in a dress and make-up, crying. He remembered sneaking him into his room and sitting him down on his bed before searching through his closet for some better clothes. He remembered how Nagisa, looking small in too-big clothing but a thousands time more comfortable, had whispered the truth about the monster his mother was. And he remembered soothing the boy, talking softly to him even as murderous rage flooded his veins.)

Nagisa needed the simple reiteration that he was a boy. That other people saw him for himself. And the gendered 'kun' that was used in reference to boys was the least Karma could do, as he'd learned.

"Say, Nagisa-kun, when are we having a rematch?" Karma drawled, smirking. "You know, I only let you win last time."

And finally, Nagisa lifted his head to meet Karma's eyes. His gaze was still a little unfocused, but icy eyes settled on his.

"There you are," Karma murmured, so just the two of them could hear.

He swung his feet off Nagisa's desk, and instead leaned forward to study Nagisa's face closer, reaching out thoughtlessly to tilt Nagisa's chin for a better angle. It was just the one bruise, but it made his blood boil. Nagisa's hand came up to cover his, and the gentle reassurance stifled his rage.

The bruise was only part of the problem, and a part Karma could focus on later.

"Here," he muttered, producing two hair ties from his pocket and slipping behind Nagisa to carefully pull up his hair in his signature two pigtails. The gesture was practiced and helped to relax Karma a little more.

"Much better," he remarked, coaxing a small smile from Nagisa.

"You didn't let me win last time," Nagisa informed him softly.

"I certainly did, Nagisa-kun," Karma teased. "Why? You planning on proving me wrong?"

Maybe it was Karma's method to deal with his problems through violence, but Nagisa had taken to it too. In Karma's opinion, most issues could be solved with a knife. And since Nagisa wouldn't let him stab the one bitch he desperately wanted to stab, this would have to do.

Nagisa's gaze sharpened, his eyes taking on a slight eery glow. "Of course."

Korosensei blurred into the class at that moment. "Good morning cl-" Korosensei squeaked as Karma threw a knife at him, phasing out of the way.

Karma tugged Nagisa by the hand to the door, despite the boy's murmured protests about missing class. They left behind their shocked classmates and indignant teacher and Karma offered Nagisa a more gentle smile as he pressed a knife into the boy's hand.

Screw Korosensei, Karma decided as Nagisa faintly returned the smile, his friend needed this – needed him. Anything else could wait.