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Little Brother

Summary:

Katakuri wasn't expecting to meet Mugiwara Luffy before the war at Marineford. He wasn't expecting to get interested in the chaos the rookie would cause by storming Impel Down and Marineford. And, he wasn't expecting him to be the son of Dragon, the only man that got away from them after stealing a child seventeen years ago.

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Big Mom is Luffy's mom theory.

Notes:

I do not own One Piece. (I've seen this everywhere so I'm guessing I should put it in here too?)

If you find this on Fanfiction under the same author name, it's me. I don't have plans of uploading it anywhere else so let me know if you find it elsewhere.

This is a one-shot. For now. Like, maybe I have an idea or two but not enough to make it into a longer fanfic.

Any new info about Big Mom, Kaido or other characters that came out after the scene in which Luffy needs tickets to get food in the Wanokuni Saga is unknown to me, as I'm watching those episodes in the anime and won't be back to reading the manga until I'm out of episodes to watch. (But I did get some spoilers and I think it doesn't make much of a difference here.)

So, the idea I had for this came from thinking about Luffy's mom. There's these crazy theories that made me think about it, and I just went the chaos route. Also, I love Katakuri and he kind of took control of the POV and didn't let go. You gotta love the mochi man.

There's more notes at the bottom, but for now, all warning you need is that there's spoilers on everything that happens from Kuma sending Luffy out from Sabaody to the end of the Marineford War. And of course, some spoilers on the Whole Cake Island Saga.

(See the end of the work for more notes.)

Work Text:

One Piece One-Shot

Little Brother

Charlotte Katakuri stared down at the kid (because it was a kid, younger than most of his siblings, innocent yet strong willed) in front of him. Injured, so obviously tired, but even then, he was raising his fists as if preparing to fight.

That straw hat of his fell off his head onto his shoulder plates, kept there only by a cord, and Katakuri wondered if the fact that the kid had just fallen from the sky should bother him.

An eyebrow raised in reaction to words that had yet not been spoken.

"Who are you!? Where is this island and how far away is it from Sabaody! I've gotta get back there and kick that stupid Kuma and stupid Zaru asses!"

"This is a deserted island, Mugiwara Luffy." Answered Katakuri, tilting his head and throwing a bag full of food to the kid just a second before his stomach protested.

"Is that food!? Wow, thanks! I guess you are not a bad guy, then!"

Innocent. He was smiling, eating the food without even a spare thought on the possibility of it being poisoned.

"I'm Charlotte Katakuri."

"So who're you?" He asked with his mouth full of food, and then laughed at being answered before asking.

"It's an ability fairly common in the New World."

Strange. Even his siblings got annoyed at that quirk of his, but this kid (not even twenty) seemed to find it cool.

"How'd you know what I was going to ask? That's cool!"

"I'm supposed to get some ingredients for Mama and get information about the war."

"What are you doing on this island if it's deserted?"

Blinking and then giggling (an honest to god giggle, was this kid younger than he thought?), Mugiwara Luffy got up, punching his palm and smiling, eyes shining and determined even when he had been obviously defeated recently.

"Okay! I've eaten, now I need a way to get to Sabaody! It's been more than the three days I told everyone, but…"

"Going to Sabaody right now may not be a wise idea, Mugiwara." Said Katakuri, taking pity of his obviously out of the loop decision. "Whitebeard is going to war against the Marine Headquarters."

"Huh? Why?"

He looked up at Karakuri, without even an ounce of the usual fear those out of his family showed towards him, and at the same time he was answering, Katakuri felt himself getting more interested in the boy.

"Portgas D. Ace is going to be executed at Marineford."

Mugiwara Luffy's eyes went wide, smile disappearing, skin turning pale, horror obvious on his face.

"WHAT!?"

Katakuri was going to add something more, maybe question why he reacted like that, but his own shock silenced him.

"I can't let them do that! ACE IS MY BIG BROTHER! I'M GOING TO SAVE HIM!"

Katakuri wasn't the type of person who would get involved in things that didn't have anything to do with him, but having brothers himself, he knew that trying to stop Mugiwara's suicide mission was impossible. But he couldn't get involved himself.

So, he just helped the kid get onto the nearer island, even if that island was the Kuja's island, Amazon Lily, it was a better chance than anywhere else.


He left the kid to his own luck, and contacted his mother.

"I want to watch the war."

"Oh? It's unusual for you to have an interest in that, even if it's Shirohige's war."

"I met Mugiwara Luffy." Katakuri paused, searching for the correct words. "He's… strong willed. Young, foolish, but strong willed. Firefist is his older brother. He said he's going to save him, so his actual plan is to storm Impel Down, and if that fails… fight in Marineford."

"MAAAMAAAMAAAMAAHAHAHAHAHA!" Big Mom laughed on the other side of the communicating DenDenMushi, clearly thinking it was hilarious. "Do you think he's going to repeat the Ennies Lobby Incident?

"It is possible." He still remembered reading on the newspaper about what the rookie crew did, and what their own web of information gathered. If Mugiwara Luffy could do that for a new crewmember, what would he do for his older brother? "It would be a shame if he dies at Marineford, too."

"Will you watch and intervene if he's going to die?"

"Yes. I'm interested in his future."

Closing his eyes for a moment, Katakuri remembered the kid's smile.

"I'm going to be King of the Pirates!"

He was old enough to remember Akagami Shanks' straw-hat, and how he returned to the New World without arm and without hat, ten years ago. It wasn't difficult to put things together.

"I will order a background check for the brat." Said Big Mom, after a few seconds. "They will be emitting the war, so we will be watching too. Don't do anything to put us on a bad spot, but if you can get a debt from old Shirohige? Do it."

"Of course, Mama."


Katakuri had seen a lot of things in his life. So, when the big double tsunami got iced, he wasn't surprised. But when he felt who was on top of the tsunami to his right, he couldn't help but laugh, quietly. He did storm Impel Down after all, huh?

He just watched.

Mugiwara Luffy struggled to reach his brother, who had just been announced to be Gol D. Roger's son (Big Mom was possibly frothing at the mouth at that, he mused, before leaving the thought out of his immediate concern), and yelled, and screamed, again and again, his brother's name.

"I'M YOUR LITTLE BROTHER!"

The battlefield seemed to pause at the words, and then, that blasted Sengoku had to announce it.

"They grew up together, but have no blood relation. Monkey D. Luffy's father is not Gold Roger." And then, when everyone was breathing relieved, he followed with the damned words. "His father is Dragon, The Revolutionary!"

Damn it!

Katakuri remembered very well the only man that had escaped their clutches that time seventeen years ago. Mama had been very upset at losing one of her children. It was a rarity, an only child, with a smile of sunshine at just a few months old.

Thinking about it, it made sense. Luffy did eat all that bag of food Katakuri gave him in less than five minutes, made use of a usually absurdly weak devil fruit with ease, had strong instincts and a will to not give up even when things seemed to look bad.

Now Katakuri would have to help, because without even knowing it, Luffy had involved the Charlotte in the war. Ironically enough, no one else knew. Maybe not even his grandfather, who looked so troubled by the side of his non biological grandson.

But first he would watch. Observe. Learn.

He would only intervene if Luffy was going to die.


Portgas D. Ace was going to be executed. The first attempt was stopped by Crocodile (the Shichibukai, who had fallen at Luffy's hands, was now helping him?), and the blades were going down for a second attempt. Luffy was too far away. He was tired, breathless, and without knowing it, leading an army with his strong will of not giving up.

The blades went down.

And Luffy, screaming, letting out a strong wave of willpower.

The Conqueror's will. Haoshoku.

Katakuri cursed under his breath. One in a million, and it had to be him.

Mama was going to be displeased at not having a hand in raising Luffy, Katakuri could hear her grumblings already.


He kept watching. Firefist was freed after Luffy punched his own grandfather (The Marine Hero, fallen with just a punch, that was clearly his way of helping his grandsons), and protected himself and Firefist from Sengoku The Budha's strike.

The moral was high, but then, Admiral Akainu said something. Katakuri was too far to hear it, but he could see the consequences. Firefist was going to stop, was going to fight against someone too strong for him.

Portgas D. Ace would die.

Sometimes, his Observation Haki wasn't something Katakuri liked so much. Seeing his own brother -because Luffy was possibly his little brother- in shock after Firefist's death made him react sooner than he would have if he had just seen Portgas dying.

When the magma fist went directed against the back of Portgas D. Ace (the idiot was protecting Luffy with his own body, without even using Haki, already knowing he would die), a wall of something white and sticky raised from the ground, separating both, and Katakuri appeared, fist covered in black, Armament Haki at his strongest, and punched the Admiral.

Once again, the battlefield stopped in shock.

"Isn't that!?"

"What's someone like him doing here!?"

Luffy looked up, eyes wide, breathless and obviously tired, and smiled.

"It's you!"

Katakuri nearly rolled his eyes. How could he not, when the kid was practically dead (bad choice of words) on his feet?

"It would be a shame if you died here." He said, not specifying, and then smirked, hidden by his scarf. "I heard you did storm Impel Down. You picked my interest and I got permission to intervene from Mama if it looked like you were going to die."

"Why are you…?" Luffy trailed off an let out a giggle. "Right! Thanks!"

"GURARARA! You have my thanks, brat!" Called Shirohige. "Marco, get those two out of here."

"Got it, Oyaji!"

"I'm not fucking running away from this fucker!" Yelled Ace, pointing at Akainu, although he was pale, clearly affected by his near-death experience.

Katakuri was going to shut him down with some good big-brother advice (something about worrying himself with Luffy before fighting more), but then, he saw something happen just before it happened.

Luffy collapsed.

He just fell down, unconscious.

"Aahhh, I knew that would happen!" Yelled Ivankov. "He's been moving nonstop for hours!"

"Luffy!" Ace yelled, insult to his adoptive father forgotten at his younger brother's state.

"Let's go already, yoi!" Called Marco the Phoenix.

"I will carry Luffy-kun, don't worry about him!" Said Jinbe, stopping just after grabbing the boy, looking at Katakuri in askance. They knew each other, of course. There had been talk of, in the possibility of Shirohige falling, Jinbe joining Big Mom's crew in exchange for Fishman Island's protection.

"Luffy can't die." Said Katakuri, voice low. "There's a high possibility he's family. Dragon stole a few months old child from us seventeen years ago."

"Why are you…?" Jinbe interrupted himself at getting answers of his questions before he could formulate them, and then nodded. "He proved himself to me already, I'm not going to let him get himself killed."

When minutes later Akainu marked Luffy's chest with what years after would be a big scar, Katakuri let himself get angry. Haki infused fists impacted on the Admiral while the pirate Buggy saved Luffy and Jinbe.

Too distracted in his battle with Akainu, Katakuri didn't pay attention to Trafalgar Law until he announced he would save Luffy's life. Then, with the submarine getting away, Katakuri made mochi walls to stop the attacks from all three admirals.

Unfortunately, the war didn't stop even with Whitebeards death. Not even when one of the young marines (another child, another young teen, his just awakened Observation Haki turning the war into torture for his senses) screamed at Akainu to stop this war, this nonsense, they got away, Shirohige was dead, why where they still fighting!?

Katakuri liked that kid too. Strong will. And undoubtedly knew Luffy somehow, seeing how they interacted when their paths intercepted earlier.

He didn't need to intervene, though, as Akagami Shanks arrived. To, as he would say a second later, put an end to the war.

He hoped Mama wouldn't be too displeased by being Akagami the one to end it and not Katakuri himself. He was occupied trying to kill Akainu.


The escaped prisoners from Impel Down used a stolen ship to get away, and Katakuri joined them, knowing already they were going towards Luffy.

"Katakuri."

He turned around slightly, his eyes finding easily Emporio Ivankov.

"Is what you said earlier true? There's a possibility that Mugiwara-boy is family?"

"Yes." Usually, he wouldn't have followed up his answer, but he had seen that the only reason Luffy could even move was because of this person. "Dragon stole a child from us. He is old enough to be that child."

"It's difficult to think that he would steal a child." Argued Ivankov.

"It was also his, biologically."

That shut up the Okama Queen.


Trafalgar Law was an interesting person. Katakuri took interest on him when he appeared as a rookie (the Ope Ope no Mi, that disappeared after a Marine operation gone wrong) and couldn't find where he came from. The Surgeon of Death had saved Luffy's life on what seemed to be a whim, and unknowingly gained his respect. He had spent hours operating, and instead of going to sleep and letting his crewmembers inform the others about the state of his patients, he himself went out to talk to them.

"Mugiwara-ya is in a coma right now. He should wake up, but I'm keeping an eye on him just in case." He didn't really seem worried by Katakuri's presence. "Jinbe is stable, he will wake up soon."

Before they could think of where to go now, Boa Hancock appeared and offered her island as a place for Luffy to rest. Katakuri had pieced together that Luffy had somehow got her help to get into Impel Down, but it was still surprising that the male-hating Shichibukai could accept the presence of men on her island.

"And we are going to marry and…! Aaaahhhh~!"

"Keep yourself together, sister!"

Or maybe not.

It was amusing how easily could Luffy cause others to follow him, be it by his determination, will or endearing himself to them. It was possibly that same ingenuity that caused Katakuri to lend him a hand.

"I will go back home now. I will be back in two weeks. I just need some of Luffy's DNA."

"His DNA?" Repeated Trafalgar, and one of his crewmembers whispered something to him, causing his eyes to widen. "I understand. Although, Mugiwara-ya is not the type of person who would accept someone giving him orders, so even if it is a positive result, you shouldn't force him."

"I did realize that already."

Smile hidden by his scarf, Katakuri left soon after, and the moment he reached Whole Cake Island, everyone was waiting for the results.

Was Monkey D. Luffy a Charlotte? Was he their lost brother?

Notes:

What a plot twist it would be if he wasn't! I was tempted to leave it at that or write "He wasn't" but I'm not that cruel. Maybe. I mean, this is supposed to be a oneshot. And I thought I couldn't write oneshots. For now I'm out of ideas (there's a "maybe Katakuri could help Luffy train but what about Rayleigh" around there) so I accept any suggestions!

Oh, by the way, English is not my first language. I've been writing in English for around a year now, but this one is the first I've uploaded (the others are loooong). Tell me if you find any grammatical horrors or any mistake, as I'm pretty much unable to find a beta that would stay with my change-fandoms-every-three-months BS as apparently watching every anime of more than 26 episodes and getting obsessed with it is not normal(?). I'm my own beta, waiting until what I've written isn't fresh and I can read my own fics being brutally critical with it, although this time I didn't wait because I felt happy enough with it (usually there's this "it could be better" feeling).

Anyway, thank you very much for reading! And even for clicking! And if you leave a review you will probably make me cry but that's good- maybe- I mean- yeah, I better go distract myself and totally not stare my mail in wait for reviews or something. Yup. Okay, this is bad, I'm nervous and I didn't even save this yet!

Originally published on Fanfiction the 1 of June of 2020.