"You're not real," their baby brother insists adamantly for the fifth time, and Ace and Sabo share a look of actual distress.
Because Luffy is staring at them blankly, as if they should know very well they don't exist. Sabo tries again.
"We're right here in front of you," he says slowly. "You're talking to us, how can we not be real?"
"I've had dreams like this before," Luffy says simply. "Dreams just like this, where you were real and I could touch you and talk to you. But I always wake up."
"Why would you dream about us like that?" Ace asks carefully, and Luffy's head swivels at once to him, and there's an ache in the silence that follows.
Sabo doesn't like the way he's drinking them up, bright eyes like a sponge. They found him sleeping on the deck, sprawled out like the overgrown kid he is, and when Ace picked him up to carry him inside, Luffy woke up, regarded them in surprise, and remarked, "Oh, this one again."
So now they're sitting outside at three o'clock in the morning failing to convince him of reality.
"It's late," Sabo says like a peace offering. "Let's just go in and get some sleep, and we can hash details out in the morning, okay?"
It isn't the first time they've lost sleep over one of Luffy's whims, but it's the first time it's ever been something as weird as this. But Ace hops off the railing, and offers an arm to Luffy the way he always does and Luffy skips a step closer with perfect timing born of countless repetition. Ace tugs him close against his side, Sabo slips an arm in there too, and the smile on their little brother's face is warm and wide and soft and sad all at once.
They're half-hoping Luffy will have forgotten the whole thing by morning, but he doesn't. Because when their cook slides some food over to him, Luffy tucks in, smiles widely, and says "Sanji's food is way better, but this is still really good!"
They've never heard of a Sanji, and Luffy's been theirs since he was seven.
"Who's Sanji?" Sabo asks casually, and he might as well have flipped the light on in Luffy's face because the boy beams.
"He's my nakama! He came from a restaurant on the sea, can you believe it? He's the best cook, and he's gonna find All Blue someday. How awesome is that?"
Sabo looks at Ace in a near panic, because their little brother must have hit his head or something, this was serious, but Ace is grinning fondly like he can't even help it.
And even though Ace should know better than to encourage him, he asks, "How many nakama do you have?"
"Eight! And they're all gonna be the best in the world!"
Looking at him, they almost believe it.
Days go by, and Luffy still says odd things and insists he's dreaming, but other than all that he's the same Luffy. Running around and getting into absolutely everything he shouldn't, and demanding songs and stories and food, and somehow falling overboard twice in three hours, and the whole crew is worn out by the end of the day but content and smiling as Luffy sings the chorus of an old pirate song none of them know the words to.
Sabo's still worried, and Ace is too, but their little brother turns to them, grinning widely, and he could be crazy as a lark for all they care, he's still Luffy. And as long as he's safe and happy, he can believe whatever he wants.
So when he teaches them the words to Bink's Sake, they listen and learn and sing it with him into the darkest hours of the night, and for some reason, out of nowhere, surrounded by nakama on a ship they call home, they feel lonely.
A Baby Den Den falls onto the deck out of thin air. Everyone stops and looks around in surprise as it starts to murmur "puru-puru-puru" and it's Luffy, of course it's Luffy, who wanders over and picks up the receiver.
"Hi, it's Luffy, I'm gonna be pirate king!"
Sabo's exasperated, "You really answer the Den-Den like that?" is almost lost under Ace's laugh.
There's a mess of static, and a jumble of voices all at once, and then "Luffy!"
And their little brother's face changes in a heartbeat, and he drops to the deck on his knees and scoops the Den-Den to his chest. "Nami! Nami! Is that you?"
"It's Luffy- everyone, Luffy answered!"
"Captain, are you alright?"
Ace and Sabo are wearing the same stunned expression, and they share a quick look of surprise. Neither of them notice when the flag falls limp against the mast and the sails flatten out as the steady winds die.
"Guys! I knew you'd figure something out! You're all okay?"
There's static, and a scuffle, and then a male voice answers clearly.
"We're fine, Luffy- that man you were fighting did something strange, opened a pocket in the air as you flew at him, and you disappeared into it."
"Ah? A pocket? That sounds weird."
"It was weird, trust me. Anyway, moss-head and I beat the shit out of him until he told us how to get you out."
Luffy nods, as if all of this is perfectly normal. "Okay. Hey, is he still there? Ask him why Ace and Sabo are here, too."
"What? Ace and who? I'll ask, hold on- and I mean it, don't you dare lose this connection, Luffy."
Luffy's sitting patiently, but his grip on the snailphone is white-knuckled. It's just the three of them all alone on the wide deck now (where did the crew go?) and night's beginning to fall. After a moment, Ace moves to crouch beside him, close enough that their shoulders brush, and Sabo kneels at his other side.
And they're forced to consider the possibility that Luffy might have been right about reality all along.
"These are your nakama?" Sabo asks quietly, and Luffy nods.
"My treasures." He turns wide, dark eyes to his big brothers, and, with a maturity that's twice his age, looking older than he has any right to, he says, "I love you both a lot. You know that, don't you?"
They don't know what to say, and they don't have time to think of anything before a new voice, somewhat frantic, is on the line and all of Luffy's attention is stolen away again.
"Luffy? Are you still there?"
"Usopp! Yeah, I'm here."
"Okay, the guy says he ate the Pocket Pocket Fruit, and he stuck you in a fishbowl. Does that make sense? It's not a real place, and it'll break apart once you leave it, but it's sort of like a little bubble you can't see. We can see it though, sort of."
"What a funny fruit!"
"The New World is so weird, I swear-"
"How long have I been in the fishbowl?"
"No more than an hour. Why?"
"Because it's been almost a week over here!"
"What? Really? That's so crazy! I wonder why? Oh, here- "
"Luffy, it's Robin. I think that it's most likely a mental projection. Apparently, the fishbowl is usually quite impossible to escape from, especially from within, because the 'fish', as we'll put it, can't distinguish the projection from reality. The Pocket-Man is actually quite perturbed that you weren't tricked by it, it made it easier for us to reach you with the Baby Den Den."
"What is he, an idiot? Of course I knew it wasn't real."
It's pretty dark by now, and there aren't any stars in the sky. That's pretty weird, Sabo thinks, but a quick glance at Ace shows he hasn't noticed, or maybe he doesn't care.
"We're gonna break through with Sunny," another new voice says. "Just keep this line open, don't let anything happen to the Den-Den, and we'll be able to follow it to you." There's a flurry of background noise, and then, "Pocket-Man says it's impossible, but he doesn't know us very well."
"You got it Franky! Zoro?"
Luffy grins widely, and even if these nakama of his can't see it, his brothers are almost certain they'll hear it in his voice. "Hi Zoro!"
There's laughter, a few groans, and the first voice- Nami- snaps, "Don't joke around until after we have you back safe, moron!"
"Sorry, sorry. How much longer?"
"Yohohohoho! This reminds me of a song- "
"Brook, not right now! Just a few more minutes, Luffy, just wait a little longer. And whatever you do, don't hang up!"
"So you're leaving," Ace says bitterly.
Luffy glances at him, and frowns.
"Of course I am. You heard it, my crew's on their way to get me."
Ace shrugs and Sabo shivers, rubs his arms, glares mulishly at the boards underfoot. Luffy looks between the two of them, scowling.
"What are you sad for?" he scolds, and they blink at his tone. "I'll always be your baby brother, no matter where I go. Even if we never meet again. Don't you know anything?"
The world breaks, the horizon shattering like a mirror, and foreign wind rushes in from the white spiderweb of hairline cracks, rippling out from a central point above the ocean a league away.
Luffy's watching with bright, eager eyes; Ace and Sabo have lost him, if they ever had him in the first place.
Ace reaches out to brush the hair out of Luffy's face, rests his hand on Luffy's head for a long moment. "It'll be weird not having you around," he finally admits, and Luffy makes a face at him.
"I'm gonna be pirate king," he says matter-of-factly. "I can't depend on my brothers forever."
"I wish you could," Sabo tells him, and from the way Luffy looks at him, he gets it. Sabo's put two and two together, and he knows that somewhere- in another world- he and Ace have died, and left Luffy on his own. And though he doesn't know the story, he knows that Luffy has moved on. And it isn't fair that they're going to lose him, but it's not fair to make him stay. "I'm sorry- I'm sorry you can't."
The rubber boy blinks, and then a smile stretches across his face. "Don't be sorry," he says. "I'm okay. Maybe this would have been a lot harder on me in some other world where I never had to say goodbye to you, but I did. I love you, but you're gone."
Ace hangs his head, scrubs his face with one hand, and Sabo wraps an arm around Luffy's shoulders.
Luffy shakes his head. "You still don't understand. You're gone but I'm okay. Because- "
There's a deafening boom that seems to shake the very planet on its axis, and sky and sea fall away to make room for a great ship, with a lion figurehead and a grinning, strawhatted Jolly Roger, that appears out of absolutely nowhere. It's close enough they can hear the wood and ropes groaning as it bears toward them; Ace and Sabo duck their heads against the sudden spray of water rushing over the deck.
But Luffy runs to the rails, hops up and grabs hold of the rigging for balance, Den-Den tucked into one arm while he waves with his other.
Several people are leaning out over the sides of the approaching ship, waving back and calling out as they casually break the laws of physics.
The ship draws up beside them, and a girl with a Log Pose and no small amount of fierce determination yells, "Luffy, hurry aboard! We only have a few minutes!"
Because the ASL ship is dissolving, the sky is slowly falling apart and the sea is fading to gray.
Luffy spares his brothers a quick glance, and something in his eyes is fond. "You're gone, but my nakama are still here," he says firmly, like it's the only math that matters, and his smile doesn't waver; nothing about him does. "One day, I'll tell you all about my adventures, but that won't be for a long, long time."
"Luffy!" A green-haired man with one eye and a scar is leaning out, holding out his hand, and without another word Luffy's stretching his arm across the gap between their two ships, and he's being pulled away.
They can't even come up with a goodbye as they watch him sail away. But oddly enough, there's no yearning, or anguish, or even sorrow as the lion ship vanishes again as unnaturally as it had appeared and the cracks widen across the sky until the whole world is falling in on itself like a house of cards, the two of them falling with it.
There's pride instead, and the last thing they know is the warmest, most welcome sense of home.
"So what was it like, Luffy?"
They're gathered on Sunny's grassy deck, clustered around their captain comfortably with a rich picnic spread out on a blanket beside them. Luffy's laying on his back, with Chopper in one arm and Usopp in the other, and he looks at Sanji upside down.
"The fishbowl?" The cook nods, and everyone else is waiting for an answer, too. So Luffy hums, thinking about it for a minute. "I dunno. It was pretty weird. Ace and Sabo thought that I dreamed up everything about you guys." He grins and sits up, drawing his arm out from under Usopp, to plop his hat on Zoro's head because the swordsman is already dozing off. "I knew I didn't dream you though."
"So Sabo was your brother, too?" Nami asks gently, and her captain nods.
"He died when me and Ace were still little. It was pretty neat seeing what he would have looked like all grown up! He was way taller than me, like thiiis tall."
"Well in any case, I'm glad you're back," Franky says, toasting him with a bottle of Cola. "We were pretty worried when you disappeared."
"And Pocket-Man said you wouldn't want to come back. He said no one ever wanted to come back before," Chopper whispers, with a hint of fear in his voice that Luffy squashes by scooping him up and hugging him fiercely until the little reindeer giggles.
"I told you that guy's an idiot." Luffy flops down again, smiling like the cat that caught the canary. "I spent two whole years getting stronger and stronger, and stronger and stronger, so I'd never ever lose you guys again. There's no way I'd choose a fishbowl."
"Told you," Zoro contributes from under the straw hat, and Sanji throws a fork at him as Nami snaps something about blind faith, Robin grows an extra arm in the grass by Luffy's head to stroke his hair in a gesture she has no clue is a lot like Ace's, and as Franky laughs and Brook picks up his violin, Luffy hugs Chopper and Usopp closer, closes his eyes, and welcomes himself back home.
I could never have dreamed this.