It's kill or be killed in the mafia. Everyone knows that. Tsuna knows that. There's no way he could forget Reborn's lesson or he'd risk losing his mind on training. 

Lesson #27 : Body language could tell you a lot about someone. So pay attention to that dame-Tsuna.

So Tsuna learned how habits and preferences worked and why someone have such a habit. 

"Kyoya won't hurt Liam, Hayato." Tsuna drank his steaming hot chocolate, watching over the lush garden from the balcony of the Vongola mansion. "Well, a few broken bones, as usual, but nothing fatal to land him in Shamal's care, at the very least."

Hayato blanched, his face chalk white at the image of the new addition to Kyoya's group with protruding bones and an unidentified disfigured face. 

'That doesn't make me feel at ease at all!' 

It wasn't actually the first time Kyoya had beaten the shit out of his new recruits just because he didn't like them. In fact, those guys he'd incapacitated were often brought in to Shamal's hating care or, if worse comes to worst, were delivered to the morgue to be examined. 

Poor bastards. 

"He'd be dead meat. You know Liam would be wishing he should've just ended up dead by the end of the day." Hayato reminded the brunet in a as-a-matter-of-fact tone. "I can't even listen to animal channel without wincing because of him." 

Tsuna sweatdropped at that but didn't miss how Hayato's feet subconsciously shuffled closer to him after saying those words. How the silveret's eyes wondered around in panic as if what he said, such a funny thing to hear, would summon the demon prefect. 

He immediately realized that it's Hayato's own act to protect him or so he could bolt away at first sight of the skylark with him in tow. 

Probably both. Whatever happens first. 

Tsuna mentally shrugged at the thought, opting to drinking his warm beverage with delight. He'll simply deal with it when it happens. 

"Tenth, you know how Kyoya acts around those weaker than him. He'd murder the new kid just because he could get away with it, and he'd always have evidence as to why to boot!" Hayato was hysterical by that point. His hands were clammy and shivering from remembering what the prefect's reasons had been when he was assigned to sorting the paperwork. 

I mean, who gets killed because of stealing Kyoya's album of Hibird? Let me tell you, it's the unfortunate soul who stumbled upon it on his desk, that's who!

Tsuna's face stayed as serene as ever.

"That's funny, Hayato. Kyoya isn't an idiot. He knows the trouble he's digging himself in." The brunet's laughter sounds like the mellow sound of tinkling bells. The mirth in his eyes playing a song of mischief. 

"But!"

"No, there won't be dead bodies this time. Or mangled victims. Or injured staff. I made sure of that." The conviction in Tsuna's voice sounds like how Reborn promises that he'd put a bullet through their heads if they screwed something up.

It scared Hayato. 

"Though if we did end up with traumatized staff and a dead recruit, well, I think strapping Kyoya down while we show him a video of a vandalized Namimori would be a nice punishment." 

'Kyoya, I hope you haven't killed anyone yet.' He prayed to the poor soul. 

Really, Hayato's getting scared of his boss. 

The nice and merciful brunet is quietly turning sadistic and Tsuna, the innocent young man that he is, isn't even aware of it! 

"What doesn't kill you makes you stronger, you know." Tsuna once told him after a session of counseling Mukuro, who was as still and silent as a rock. A shivering and terrified rock. "And Reborn did tell me that I need to keep those under me in line no matter what."

Hayato shivered at the memory, sparing a contemplative look at the humming brunet.

"Besides, Kyoya loves adorable things too much for him to harm the guy. I mean, have you seen how his eyes would linger on Xanxus' feather accessories?" Tsuna pointed out to the gaping silveret. "It's quite ridiculous how he'd throw tantrums after Xanxus' visits and go AWOL on us. Honestly, Liam's got to be lucky cause he knows how to tame and talk to birds!"

Really, Hayato doesn't know if he should be awed at his boss for noticing that, be scared for noticing the stoic man's habit, or be delirious with happiness that he won't have to bury another body in the garden.

Every action has an equal and opposite reaction. A typical Newton's law. Tsuna didn't know that the same thing also applies to behavior. 

"Lambo, please put that cake back in the fridge." Tsuna called out to the 12 year old hiding behind the kitchen counter. "I know your new favorite changed from grapefruit to caramel flavored sweets, but I've set limits, remember?" 

A spluttering noise resounded behind the counter. Lambo emerged, a bewildered look on his, carrying a plated slice of cake on his hands.

"How did you know that, Tsuna-nii? For all you know, I could've been bringing this for someone else or maybe was ordered by the stupid octopus to get it." Lambo tried to reason out. Trying to weasel his way out of having his older brother figure and boss to laugh at him. 

Caramel eyes gave Lambo a knowing look and a humoring smile.

Tsuna placed the new batch of cookies, straight out of the oven, on the table to cool down. Lambo gulped down the pooling saliva in his mouth as he scented the smell of the cookies. 

It appears drool worthy, and really, everything the brunet makes is delicious!

"It's for I-pin, isn't it?" Was Tsuna's sly question after taking his baking mittens off. "I suppose you want to cheer her up."

The silence continued. Tsuna sat down on a nearby chair and watched his adopted little brother with a patience born from practice. And resignation of what his life had become. 

Lambo's shoulders slouched. He heaved a sigh before propping himself on the chair just opposite of the brunet. 

"Yeah. She's, I, um," Lambo pursed his lips, his hands gripping the marble top of the table. "We had a big fight." He admitted. 

Tsuna hummed an affirmation that he's listening. His mind already conjuring the scenario of a fight with what he'd seen of the young Chinese girl's bruises. "Yes, she did look upset when you returned from school." 

Tsuna saw how the teen winced. Well, that must mean that the two had their fight at Mafia Institute. The poor building must be in shambles by now. Woe is he for he is a slave to paperwork. 

But will be reserved for later. Now, he needs to know what the fight is all about. 

"Yeah." Lambo scratched the back of his head. Awkward at the reason of the fight itself now that he's thinking about it. "I guess, I got too protective of her back there."

"And I take that she didn't like it." Tsuna added and gave a smile when Lambo shamefully nod his head. "Then that is fine." 

Green eyes blinked in astonishment, watching Tsuna with wonder and incredulity. 

There was silence... then there was Lambo's explosive, if rare, temper that crackled like flashes of lightning and roared with the thunders. 

"How is that anywhere near fine?! We fought each other! We harmed each other! The school is reduced to ashes!" Tsuna's smile twitched at that but still maintained his calm. "Those bastards from the Merc Famiglia were insulting her and she was crying! How was I supposed to react to that? Then when Trian threw the first punch, it became an all out war and I'm guessing he's tattling to his old man right now! Do you understand Tsuna-nii?! We're going to be at war with another mafia family and you'd just tell me that it's fine?!"

Lambo was heaving and crying and looks significantly better that he had let his fears out. His lovely marble table is cracked, really, woe is he, and his cookies went black from the burst of Lightning flames, his poor, poor creations, but when Lambo rushed towards him in search of comfort, he knows everything will be just fine. 

Really, everyone should've known by now that he shouldn't be tested with his patience, no matter how benevolent he always looks like. 

"Shh. That's alright, Lambo." Tsuna soothed the teen who was sobbing on his shirt. "Nobody's going to die today." Not from our side anyway. "And I-pin will accept your apology after she cools down. She can never hate you. She made it clear last time you played a prank on her, right?" 

Black and curly hair bobbed as the teen nodded. Lambo's misty green eyes then peaked at him from where it's burried. "Really?" 

"Yes. Now go along and talk to her. She should be alright to talk to right now." 

"Thank, Tsuna-nii." Lambo squeaked out after he dried his tears. "And I'm sorry for the cookies."

Tsuna merely gave him a smile, watching the teen's form before finally declaring the coast clear for any interferences. Reaching his right hand to his pocket, he got his phone out and contacted his most surefire and most lethal family member: Reborn. 

"Neh, Reborn, you said you've been bored staying in the mansion, right?" After hearing a grunt of irritation, Tsuna gave a dark smile, one that his guardians could recognize immediately. "How about I give you something to play with. After all, I think I just found the right reason to get rid of the Merc Famiglia." 

The next day, every mafia family heard of how Merc Famiglia got incinerated in one shot. With their sleek gun collection missing from their vault. 

Reborn's a happy camper after that. Not that anyone couldn't see with how his eyes gleamed in unholy delight. 

Watching someone's body language is a good skill. But in the mafia, you'll need to learn to adjust and fake as much to survive and live. 

Still, nobody said that Tsuna is a good liar. He's just doing things in a roundabout manner. It's no longer his fault if his enemies haven't prepared themselves to it.