Title is from Sun Tzu's famous saying "Know thy self, know thy enemy, (and then you will have) a thousand battles, a thousand victories."
Zoro is angry.
No, Luffy tilts his head as he watches his swordsman approach. Angry is not the right word. Admittedly, Luffy can't remember the last time he saw Zoro genuinely angry but even if he were, Luffy senses that it would not look like this brittle tension in the swordsman's gait, and savage determination in his gaze.
No, Luffy realizes, his own eyes narrowing in concern. Zoro doesn't look angry; he looks dangerous.
The captain hops down from Sunny's figurehead to meet the swordsman halfway. "Zoro."
"Luffy," Zoro is chillingly calm, a predator tensed for the hunt. "There's somewhere I need to go."
And just as Luffy is nodding, about to turn to his crew mates to announce a change of plans and to get ready to set sail, Zoro adds. "Alone."
"Like hell, you're going alone."
"Shut up ero cook, I'm more than enough. I'm going alone."
"No," There is enough venom in that single word that even Zoro pauses. Sanji, whose gaze is still on the morning paper Robin wordlessly passed over, grits down on his cigarette. "If you go alone, it'll just be Pirate Hunter Roronoa and that's not enough. It can't be just you, it has to be us. It has to be the Straw Hat pirates that tell the world that this," He crumples the paper in a white-knuckled grip. "Is unacceptable."
It is alarming because Luffy cannot fathom what could have possibly worked Zoro up into such ruthless control. They have been sailing along calm waves for the past few days, meeting nothing but the occasional seaking and newspaper delivery bird. No enemy could have made it past his attention.
Chopper is the one who burns the paper but all of them agree: Luffy must never know.
In the end, Franky offers to accompany Zoro and the swordsman puts up surprisingly little resistance. Luffy is puzzled at both Franky's offer and Zoro's acceptance; however, Nami and Sanji insist that Zoro cannot sail Mini Merry II alone and Zoro needs to return preferably before they find One Piece.
It is strange but Luffy doesn't ask where Zoro will go with such violence humming in his bones. He doesn't understand where this rage has come from, where it will head to or even why.
"Five days," He says instead. Even Franky, who is already down on Mini Merry II docked by Thousand Sunny's side, ceases his shouts for supplies to listen. "You have five days, Zoro. Then, you come back."
Zoro, Usopp calls just as the swordsman begins climbing down Sunny's side to aboard Mini Merry II. The sniper tells him quietly, the words slow, measured and all the more sincere. Make them afraid.
They are all sprawled on the deck, singing along to Brook's new song, when Nami calls out, "Luffy! I think Zoro and Franky will be returning soon."
Luffy is busy cheering with the rest of his crew mates at the good news; he never notices the sharp smiles his crew mates share, nor the morning newspaper Nami tosses into the sea without a second glance.
(IMPOSTER OF PORTGAS D. ACE FOUND DEAD. CREW MATES GONE MISSING. INVESTIGATION AT DEAD END.)