It's arguable who notices first. It might be Takeshi, who is always sensitive to tension in the air. It might be Hayato, who's far too intelligent for his own good. It might be Ryohei, for his sheer persistence when it comes to Kyoya.
Regardless, the issue is soon discovered. It's actually less of an issue and more of a concern for the former prefect of Namimori Middle. After all, Kyoya must be sick if they don't feel up to fighting Mukuro on sight.
Hayato, Takeshi, and Ryohei watch the two with guarded eyes, ready to intervene on behalf of the busy Tsuna(Tsuna is drowning in paperwork and none of the Guardians want to touch that with a forty foot pole). Kyoya's eyes scan Mukuro's visage-Mukuro seems different today and none of the other Guardians can put a finger on why.
Abruptly, Kyoya straightens out of their crouch and slides their tonfas back into their sleeves. Tetsuya lets out a quiet sigh, earning a glare from his boss. He's tempted to roll his eyes at them but knows that will only spur their ire.
"Come find me later," Kyoya mutters to Mukuro, who chuckles.
"Kufufufu, alright." Mukuro abruptly disappears in mist, as dramatic as ever. Kyoya stalks forward, past the gaping onlookers. Hayato shakes his head, simply done with the confusing duo.
"Hahaha, I thought those two would fight like they always do!" Takeshi says, laughing in that irritating way that grinds Hayato's nerves. Hayato rolls his eyes in exasperation.
"Something must be up, sword freak. That person wouldn't just pass up a fight with Mukuro," he says, almost sounding concerned(listen, it's not as if he cares about either of them. He's just concerned because on what day does Kyoya ever pass up a fight with Rokudo Mukuro?). Ryohei practices his punches in the air, already caught up in his constant state of training.
"LET SLEEPING DOGS LIE, OCTOPUS HEAD!" Ryohei yells in a moment of brilliance.
"Screw off Turf Top! We should alert the Juudaime about this!" Hayato hisses to his fellow Guardian. Ryohei swings a fist at Hayato, who barely dodges the deadly punch. "Watch where you're aiming!"
"OH I'M SORRY DID I ALMOST HIT YOU OCTOPUS HEAD? MY BAD!" Ryohei's grinning in a way that says he's not sorry and since when did that idiot learn the concept of sarcasm? Hayato doesn't know, but he will find out. Whoever taught him will be shot, buried, dug up, and shot again.
(Reborn, of course, welcomes the challenge.)
Chrome is walking down the corridor, trying to submit a report to Tsuna for the last mission, when Kyoya thrusts a tonfa into the wall. They're agitated, Chrome can tell. Smirking, Kyoya lights up their tonfa with Cloud Flames and thrusts it forward. Narrowly, Chrome dodges. There's a calculating look in both of their eyes, each gauging their opponent.
"Cloud person," Chrome greets flatly, almost aggressive. Kyoya grunts and violently throws their body forward to get closer to the other. Chrome has a height advantage, they know, and they have to overcome that if they want to beat Chrome.
"Pineapple herbivore," they say as an afterthought, tonfa engaged with a trident. Footsteps echo down the hall and both Guardians pause the slightest bit. Hayato and Tsuna round the corner, alarm on their faces. Tsuna looks like he wants to scream and Hayato does end up screaming.
(Though their screams are vastly different; Hayato's is more of an angry scream while Tsuna's is a horrified one. No matter how many years pass, Tsuna will never get over Kyoya's presence and need to fight.)
"Hibari-san stop fighting him now!" Tsuna screeches, pleading with his Cloud Guardian. Hayato blinks and squints at Chrome. He doesn't see Mukuro anywhere.
"Hnn," they disagree, as Chrome throws a weak illusion their way. He's setting up for another, bigger one and needs to distract Kyoya. Of course, the Cloud Guardian sees through it. They've spent a good amount of time combating Mukuro's illusions, and Chrome isn't as nearly as strong as his counterpart.
"I will fight in place of Mukuro-sama, Bossu," Chrome tells him, gripping his trident tightly. Hayato has no actual idea what's happening. Chrome is sweet, shy, and would never attack Kyoya. Uncertain, he shuffles to the side, a stricken look on his face. Tsuna cries softly as they continue their assault on the Mist Guardian.
"Can't you do this in a training room?! There are antiques lying around everywhere!" Tsuna shouts in exasperation. A vase falls and breaks, and Tsuna squeaks. He's going to have paperwork now!
Kyoya barely flinches as Chrome catches them in a stalemate. Tsuna hurriedly swallows a pill and rushes between the two. His face is calm but his eyes burn with anger.
"You will both stop now. No arguments! Go find a training room and beat each other within an inch of your lives there, I don't care! But if you break anything, and I do mean anything, you will both be grounded and complete my paperwork for two weeks!" Tsuna scolds the two like he used to scold Lambo. Neither backs down and Tsuna increases the intensity of his Flame. "I mean it!"
Chrome slowly lets his trident fall. Suddenly, she releases the illusion she had cast over herself and Kyoya scowls. They have no interest in fighting Chrome anymore. Tsuna sighs and exits Hyper Dying Will Mode.
"Sorry Bossu," Chrome apologizes sweetly, her fingers gripping her trident tightly. "I can put an illusion on the vase we broke." Hayato snaps out of his reverie and marches forward, his finger in Chrome's face.
"Wait, why did Hibari stop fighting? Why did he start fighting with you and not Mukuro?" he growls, a scowl on his face. Tsuna sighs when Chrome bits her lip.
"You know how Mukuro and Chrome are genderfluid?" Hayato blinks, nods. "Hibari-san doesn't fight with Mukuro when she's a girl. Nor do they fight with Chrome as a girl. I don't know why though." He looks at Kyoya cautiously. Kyoya doesn't particularly care, though, and strolls away from the scene.
(They're totally going to go fight someone, though. Tsuna's intuition is never wrong. Kyoya can't get worked up like that and then get denied of a fight. Godspeed to whoever suffered the wrath of Hibari Kyoya.)
(Tetsuya looks terrible at dinner, and Tsuna vows to pay for medical bills and dock Kyoya's pay. It was time Tetsuya got a raise, anyway.)
A/N: Was talking with a friend about q***r headcanons and this was born. Kyoya is agender, hence the use of they/them when referenced. Chrome and Mukuro are genderfluid, and while everyone knows, it's not like they're the sharpest tools in the shed. Mostly, it's subtle but Tsuna, Reborn and Kyoya ALWAYS know. Reborn because he's Reborn, Tsuna cause he's got a connection(plus intuition)with them and Kyoya because they always know everything(like Reborn, but on a smaller scale). Tsuna scolding his Guardians like children is hilarious, in a way. Also, I feel that Mukuro is less confrontational as a girl and Chrome is slightly more aggressive.
BLEH I KIND OF LOVE THIS FOR THE HEADCANONS BUT HATE THE WRITING.
EDIT: I deleted some reviews about Kyoya's agender-ness. Thanks, people, thanks. It's not like others can have HEADCANONS anymore! And if you don't know what 'agender' means, there's always Google. Or tumblr. I wake up to rather rude things so I'm a tad testy. (There's also the fact that, I, am genderfluid and most of the time I identify as agender.)