Random Idea that had to be turned into a story: Mordred reborn as Dino's younger sister.
Tsuna didn't know whether to be relieved or mortified that his favorite teacher was walking home with him to have a long chat with his mother. Every time she attempted to set up a parent-teacher conference before, Nana would end up forgetting about it.
For once, she wasn't coming to discuss how to improve his grades. Rather, she was there to compliment and find out who was behind the sudden improvement.
He was rather horrified seeing the large number of mafioso in front of his house.
Oh gods, what the hell had Reborn done now?
His teacher had an odd expression on her face.
"Halt. Only members of the Sawada family are allowed in," said one mafioso.
Before Tsuna could say anything, his teacher spoke.
"Since when do members of the Cavallone famiglia have any authority over a Japanese citizen?" she countered calmly.
Dead silence.
"...Um, Kishi-sensei, how do you know who they are?" asked Tsuna slowly.
"Long story brat. Now move," said his teacher.
The mafioso parted before her without a word. What they found made Tsuna want to scream in frustration, because there was another mafioso in his house talking to Reborn.
"Stupid Dino, you might want to have a word with your minions," said Reborn, frowning when he saw Tsuna's teacher there as well. "They weren't supposed to let uninvolved civilians in."
Before Dino could reply, the woman snorted...before scooping up a turtle that Tsuna hadn't noticed.
"Maybe you should tell the dumbass to keep better track of Enzo," she shot back. "I bet he still hasn't gotten over his innate clumsiness whenever his men aren't around."
That got both men to stare at her.
"Who are you again?" said Dino, looking at her very hard now.
She had a wicked grin on her face as she reached up and pulled off a wig Tsuna hadn't even realized she was wearing. The hair underneath was an almost identical shade to Dino's own blonde. She then pulled off the glasses she always wore, and took out a pair of contacts revealing stunning green eyes.
Dino was gaping, and Reborn wasn't much better.
"Did you miss me, big brother?" she asked in perfect Italian.
It took Dino entirely too long to gather his wits, but when he did the first thing he said in a shocked almost half-yell was...
"Luna?!"
Tsuna looked at his teacher in confusion, while she just cackled.
"Kishi-sensei...how do you two know each other?"
"Because this dumbass is my older brother. I recognized his right hand man Romario outside," explained his teacher grinning. She then turned her attention to Reborn. "I should have guessed you were behind his sudden improvement when it came to grades...that and the new interest in public nudity."
Reborn shook off his shock.
"How long have you been here?" he asked.
"I've been tutoring Tsuna for what...three, four years now?"
Tsuna nodded.
"Pretty sure it's been at least four years," he agreed. "You started tutoring me for pocket money about three years ago, I think."
It was the only reason Tsuna had been getting semi-decent grades until Reborn showed up.
Tsuna was openly curious about his favorite teacher/tutor. She was the one the school called in regularly to sub, and thanks to Reborn that had been happening a lot more regularly.
She was currently handling Nezu-sensei's class because he had left for 'mental health reasons'.
Considering the mess he caused, Tsuna suspected the real reason was because he had faked his license to teach and got busted. Having Kishi-sensei take over until they could hire a replacement was a good compromise.
Needless to say her class was his favorite and Reborn never had to 'encourage' him to study for it.
Tsuna left the two alone to catch up and it was pretty clear just from watching them interact that they were somewhat close. Even if he couldn't understand Italian, he could tell from the way they interacted his favorite teacher loved her older brother.
As the night drew on, Tsuna found himself relaxing and listening intently to all the embarrassing stories Dino clearly didn't want told about his younger days. It was heartening to know he wasn't the only one to suffer an innate clumsiness. Dino in return cheerfully countered with stories of his teacher's tomboy days and how she drove their father up the wall.
It was nice, and made him wonder if this was what a real family was like.
While Tsuna was using the restroom, Reborn looked to Luna with a smirk.
"So. You're the 'Kishi-sensei' that Tsuna has a crush on," he said. Dino immediately did a spit take of his drink.
"Say what now?"
"Really?" groaned Luna. "You had to tell the biggest sis-con in the damn mafia that? Tsuna's barely fourteen, for crying out loud."
Tsuna choked, just a little at hearing that.
Tsuna looked at his favorite teacher the next morning. She had arrived extra early to see Dino.
"So does this mean you're not going to teach class anymore?" he asked.
"Why would it?" she asked confused. "I'm still your teacher, though if I had known you were being trained by the mafia's greatest asshole I would have stepped in sooner."
"I heard that," said Reborn.
"I know, I made sure you were in earshot. Did you really think I forgot half the crap you put my brother through last time?" she shot back.
Reborn scowled at her. It was too early for this without coffee.
"And really Reborn, what the hell were you thinking? Unlike Dino, Tsuna has next to no real support system to balance out the bullshit you like to pull on a regular basis. I was starting to get worried about why his behavior had been so erratic lately."
Reborn covered his eyes with his fedora.
Tsuna blushed at the fact she cared so much about him.
He blushed even more when his favorite teacher called him in class and let him know he'd be getting "after school lessons" for the next week to bring his grades up. This wasn't entirely unusual, as the entire class knew that Kishi-sensei really cared about her students.
Tsuna didn't think twice and went to the room Kishi-sensei had reserved for her after-school lessons. She had already cleared it with Hibari, and had gotten permission.
"I thought my grades had been improving recently?" he asked.
"They have," agreed Luna. "However unlike my brother, you were neither born into the mafia society nor were you in denial due to being low on the list of succession. And from the looks of things, that asshole hasn't even bothered to bring you up to speed on anything and is mostly trying to instill a spine in you. Knowing how half-assed the Vongola has been handling things lately, you don't have the luxury of time."
Tsuna wilted a bit.
"I really don't want to be mafia boss," he said quietly.
"Neither did Dino," said Luna. "The problem is that Timoteo Vongola is an ancient relic who seems to think that blood will tell even if there is someone willing to take the reigns. And the less said about that asshole Iemitsu, the better."
Tsuna had an utterly bewildered look on his face.
"Wait...what does my father have to do with this?"
Luna's expression was blank as she stared hard at him.
"You're related to Iemitsu Sawada?" she said slowly. The second she described him, Tsuna nodded in recognition. "How the fuck did the biggest braying jackass of the entire mafia produce a kid as sweet as you?"
"He's in the mafia?"
"He's the external adviser of the Vongola, and the head of CEDEF. Though he's absolute crap at his job from what I've heard," said Luna.
Tsuna was floored with this new information, mostly at the fact his absentee father was apparently very much alive.
He was still musing over all the information she had given him that he almost didn't realize they had arrived at his home.
The second Luna walked in the door, she confronted Reborn with an irate look on her face.
"What's wrong?" asked Dino. He knew that look. His sister was utterly pissed about something.
Last time she looked this angry, their older brothers had set her up with another 'nice mafia boy' from a famiglia they had hoped to make an alliance with.
She had knocked out three of the poor bastard's teeth before they managed to remove her.
Luna glared at Reborn, utterly furious.
"Are you aware Tsuna was under the assumption his father was apparently dead this whole time, and that he had no clue Iemitsu was Vongola?"
"What?" said Dino in disbelief.
"Dad left when I was seven and said he was 'off to become a star' and never came back since," said Tsuna quietly. He took silent comfort in Luna's presence. "If he ever did call, it was never when I was at home."
"Tsuna has absolutely no clue of the internal structure of the Vongola, much less who their allies are or general knowledge that even children know in the mafia," said Luna in absolute disgust. "What the hell have you been doing this entire time?"
"I've been trying to train him," said Reborn, annoyed she was challenging his authority.
"Training my ass. If that half-assed attempt you've been making up until this point is what you consider training, then it's a miracle that you managed to make Dino even half as good as he is now," she snarled. "Hell, his grades are only barely above a C average at this point!"
It was only the fact Luna was female that kept Reborn from shooting her. That and the fact she was acting out of genuine concern for his student.
Dino looked as appalled as Luna felt.
"How bad are we talking about here?" he asked seriously.
"To put it bluntly, if Tsuna were to take the rings now he'd be little more than a puppet," said Luna without hesitation. "If I had known he'd been tapped by that ancient bastard in charge, I would have stepped in months ago."
Tsuna was surprised at how angry his teacher was over this matter. It was honestly the first time an adult had been angry over his behalf and was showing clear intent to do something about it.
"Is it really that bad?" he asked her.
Luna turned to him with an expression he had only seen occasionally on his mother's face. Though it was more recently directed at Lambo, I-Pin and Fuuta more than him.
"Tsuna, the current idiot in charge of the Vongola is unlikely to actually listen to you at all because you were raised civilian. He's held the reigns so long that he refuses to listen to reason and will likely steam roll over your actual opinion because he 'knows better' and 'things have always been done this way'," she explained slowly.
Tsuna winced at the idea.
"Which is why I'm going to be catching you up on all the things most children who are mafia raised know, since Reborn has been doing jack all about it," said Luna, glaring at the cursed man.
Reborn couldn't even disagree, since he had been slacking off.
"You're not going to shoot me with those weird bullets like Reborn does...are you?" asked Tsuna timidly.
Luna's glare suddenly doubled at Reborn.
"Is this the reason I keep hearing complaints about his odd forays into public nudity the past few months?!"
Tsuna nodded.
"Please for the love of god tell me you've at least deal with the inevitable Skullitis," she said, half pleading.
"I already dragged Shamal here and it was dealt with in the first month," said Reborn.
"So the reason I've been hearing the other female teachers bitching in school about the 'new nurse' is because it's Shamal?" said Luna, incredulous.
"Shamal-sensei is the school nurse?" said Tsuna.
Luna looked just done. Reborn had made an utter mess of things and wasn't even remotely taking the job of training Tsuna seriously, and it pissed her off.
The next time he decided to slack off with training the poor kid, she was going to take out her sword and use him as her own personal pinata.
That being said she was going to have a long, painful talk with Hayato over his behavior. He was acting more like a damn stalker than a proper right hand, and she was going to put an end to that mentality if it killed her.
Odds were if she didn't, he'd become super possessive of Tsuna and kill any chances the poor kid had of getting laid.