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Usopp prides himself on being an observant man. As the sniper of the Straw Hat Pirates, his eyes are his greatest weapon. He notices the subtle shifts in the wind, the exact trajectory of a cannonball, and the minute changes in his crewmates’ moods. He is, in his own humble opinion, a master of situational awareness.
Which is why the current situation with Zoro and Sanji is making him question his own sanity.
It starts with small, almost imperceptible things. Things that a lesser man (say, Luffy, who only has eyes for meat, or Chopper, who is too pure for this world) would simply gloss over. But Usopp is a warrior of the sea, and his brain is trained to recognize anomalies.
The first anomaly occurs on a completely average Tuesday.
Usopp is sitting cross-legged on the grassy deck, diligently recalibrating a set of wind dials. A few feet away, Zoro is napping against the mainmast, which is entirely normal. Sanji walks out of the galley carrying a tray of iced lemonades for Nami and Robin, which is also entirely normal.
What is not normal is the trajectory of Sanji's foot.
Usually, when Sanji walks past a sleeping Zoro, he either “accidentally” steps on the swordsman’s face, or intentionally kicks him in the ribs just to see if he’s awake. It is a time-honored tradition of violence. Today, however, Sanji steps entirely out of his way to avoid clipping Zoro’s outstretched leg. Even worse, as Sanji passes by, he effortlessly, and without breaking his stride or looking down, drops a chilled bottle of sake squarely onto Zoro’s stomach.
Zoro doesn’t even open his eyes. He just catches the bottle with one massive hand, grunts something that sounds suspiciously like “thanks,” and pops the cork with his thumb.
Usopp stares. He rubs his eyes. He looks at his wind dial, wondering if the fumes from the gunpowder he was mixing earlier have caused temporary brain damage. Sanji voluntarily giving Zoro booze without throwing an insult? Zoro thanking the cook? Usopp makes a mental note to check the sky for flying pigs.
The second anomaly happens three days later during a chaotic skirmish with a mid-tier Marine galleon.
Usopp is perched safely on the upper deck, sniping marines who get too close to the rail. Down below, Zoro and Sanji are fighting back-to-back, a terrifying blur of flashing steel and ignited kicks. This, again, is standard operating procedure. They are bickering loudly over a kill count, calling each other a "shitty mosshead" and a "stupid dartboard" between crushing skulls.
But then, a Marine captain manages to sneak up behind Sanji with a loaded flintlock. Before Usopp can even draw his slingshot, Zoro pivots. He doesn't just block the shot; he throws his entire body in front of Sanji, taking a grazing bullet to the bicep before bringing the hilt of his sword down on the Marine’s head.
Sanji turns around. He looks at the fallen Marine, then at the blood steadily dripping from Zoro’s arm.
Usopp braces himself for the inevitable yelling. He expects Sanji to scream about not needing a stupid swordsman to protect him. He expects Zoro to tell the cook to pay better attention.
Instead, Sanji’s face does something bizarre. The anger melts away, leaving behind a look of such stark, unguarded relief that it makes Usopp feel intrusive just for witnessing it. Sanji reaches out, his hand hovering over Zoro’s bleeding arm for a fraction of a second, his fingers trembling slightly.
"You idiot," Sanji breathes. It doesn't even sound like an insult.
Zoro just smirks, reaching out with his good hand to flick a piece of soot off Sanji’s cheek. "Watch your back, cook."
They hold each other's gaze for a solid five seconds in the middle of a literal battlefield, utterly ignoring the chaos around them, before turning back to the fight.
Up on the railing, Usopp drops a pop green. His jaw is practically on the floor. What the hell was that? Was that... tenderness? From Zoro? Towards Sanji? Usopp seriously considers marching down to the infirmary to ask Chopper for a full neurological exam.
By the time the third anomaly hits, Usopp is actively trying to avoid looking at them, terrified of what his sniper eyes might uncover. But fate, it seems, has a twisted sense of humor.
It’s past midnight, and Usopp is thirsty. He creeps down into the dark, quiet ship, making his way toward the galley. However, he hears the faint hum of voices coming from the aquarium bar. Thinking Luffy might be trying to break into the fish tank again, Usopp quietly pushes the heavy wooden door open, intending to scold his captain.
The words die in his throat.
The bar is lit only by the eerie, blue glow of the massive aquarium. Sanji is sitting on the plush circular couch, his long legs stretched out over the cushions. He is smoking a cigarette, blowing a thin stream of smoke toward the ceiling.
And Zoro is lying down, his head resting squarely, comfortably, and unapologetically in Sanji’s lap.
Usopp freezes perfectly in place, his self-preservation instinct screaming at him to turn around and run. But his legs refuse to move. He is paralyzed by the sheer impossibility of the scene before him.
Zoro is fast asleep, his face turned inward, pressing into the fabric of Sanji’s trousers. And Sanji—Sanji, who claims to hate the swordsman with the fiery passion of a thousand burning suns—has his hand buried deep in Zoro’s green hair. Sanji’s fingers are moving in slow rhythmic circles, gently scratching the swordsman’s scalp.
Sanji isn't scowling. He isn't looking for a fight. As Usopp watches, utterly transfixed, Sanji takes a drag of his cigarette, sighs softly, and looks down at the sleeping brute. The expression on the cook's face is so devastatingly soft, so incredibly fond and open, that it physically knocks the breath out of Usopp's lungs.
Sanji shifts slightly, using his free hand to drape his own suit jacket over Zoro’s broad shoulders like a makeshift blanket. Zoro lets out a low, contented rumble in his sleep and leans closer into Sanji’s warmth.
Sanji smiles. A genuine, quiet, entirely private smile.
Usopp’s brain finally short-circuits. All the pieces slam together into a terrifying, undeniable truth.
Holy shit, Usopp thinks, a cold sweat breaking out on the back of his neck. They’re dating.
The realization is so heavy it feels like a ten-ton hammer to the skull. The two most violent, terrifying, emotionally stunted men on the ship are navigating a romance directly under everyone's noses, and Usopp is the only one who has noticed.
Sanji suddenly shifts his gaze, his Observation Haki likely picking up a presence at the door.
Usopp doesn't wait to make eye contact. Moving with the speed and agility of a true warrior of the sea, he closes the door, turns on his heel, and tiptoes frantically down the hallway.
He makes it back to the men's quarters, climbs into his hammock, and pulls the blanket over his head.
"I didn't see anything," Usopp whispers frantically to himself in the dark, squeezing his eyes shut. "I am just a humble sniper. I have the I-did-not-see-sanji-and-zoro-being-domestic-disease. I will take this secret to my grave so I don't get sliced into three pieces or kicked into the sun."
Down the hall, he hears a faint muffled rumble of Zoro's laughter, followed by Sanji's low voice.
Usopp shudders, pulls the blanket tighter, and vows never, ever to go into the aquarium bar at night again.