Author's Note: Time for the first full fight scene, I hope it hasn't taken too long to get to one.
The town's buildings passed by Sanji in a blur as he chased Bui through the streets, the area's emptiness just allowing him to run quicker without fear of hitting something. The long black hair of his target flowed gracefully behind him, seemingly taunting Sanji as a fluttering cape would a charging bull.
Bui gave him one stray glance but no emotion had crossed the older man's face as their eyes met. That only served to infuriate Sanji further, especially when he was forced to chase a leaping Bui onto the area's rooftops.
His Skywalk had brought him to those heights just as Bui leapt off the buildings and darted into a long field of green. Sanji's feet deftly kicked the air and pushed him to land on the soft grass below without breaking his pace.
They weren't far from the uninteresting township when Bui had skid to a stop and turned to face Sanji.
"I should warn you that any attempt to fight me will only invite suffering upon you," Bui said blankly as he spread his arms out to the side, his open palms level with (but pointing perpendicular from) his hips.
"Shitty bastard," Sanji had muttered calmly, his distance from the insulted women having cooled his temper and leaving him ready to punish the man who had besmirched their honour.
Bui sighed but said nothing further as he continued watching the chef with a bored expression upon his face.
"Well, I won't waste any more breath…" Bui said casually before vanishing into thin air quicker than Sanji's eyes could follow.
"Crap!" Sanji shouted, scanning the surroundings just fast enough to see a black-coated leg sailing straight for his nose.
Ducking the attempt, Sanji was forced on the defensive as a flurry of feet, shins and elbows were launched in his direction, the miniscule gaps between each hit leaving little to no room for a counterattack.
Eventually he turned just a fraction of a second too late and a hard elbow grazed Sanji's side, winding him. Sanji stumbled back as Bui came to a halt, his hands resting comfortably in their pockets as Sanji glared at him intently.
Bui flicked his hair from his eyes as a small smirk graced his lips, "I know you can do better but at this rate, I may as well have finished you off in town. It's not like you'd last long enough for the fight to cause any damage."
Sanji remained visibly angry for just a few moments before relaxing with a knowing sigh, a smirk mirroring Bui's appearing on his own face.
"Dumbass."
Sanji's words had barely left his mouth before his leg was swinging for Bui's neck, the distance between the two seemingly closed in an instant.
Just like that, the tables were reversed and Bui was the one unable to find an opening. Bui's leg attempted to rise to meet Sanji's but the blond man's strength proved greater and Bui's kicks were easily deflected.
Sanji spun on his heel and brought his foot up behind him so that his two legs formed an almost straight line as the sole of his shoe was embedded in Bui's gut ("Anti-Manners Course Kick!"). The thinner figure was sent airborne by the strike, clutching at his stomach in pain just as Sanji jumped up beside him and delivered another kick, this one hitting his back to send him hurtling into the ground below.
The resulting crash threw dust and rock chippings into the air as Sanji gracefully landed back on his feet and straightened his tie with one hand.
"Shitty creep makes a shitty fighter, fancy that," Sanji said with a grin as he watched the motionless Bui on the ground.
Slender fingers pushed against the dirt as Bui pushed himself back to his feet, Sanji's grin faltering at the blank expression on Bui's face as he dusted himself off.
"I guess I'll have to take you seriously after all," Bui said while using his thin thumb to brush the line of blood dropping from his mouth off his chin. "Unfortunately, that is something you will soon come to regret."
Sanji scoffed while Bui raised his open palms and took a step forward.
Undeterred, Sanji took the initiative, swinging his feet downwards twice to gather speed before rotating upwards to target Bui's body. The feminine man used his flat palm to block the attack, being pushed along the ground by the force before sending Bui flying to the side.
Sanji's eyes narrowed in pain as his leg dropped to the ground like dead weight in water, hitting the dirt with a loud crack. Sanji's mouth was agape at the sight of darkest black coating his entire leg up to the knee in one uniform colour. The chef tried to lift it but struggled under the attempt as he forced himself to his feet, shaking slightly as he did so.
"What the hell did you do?!" Sanji shouted, falling back to one knee when he tried to take a step forward.
"Tell me, have you ever heard of Bushoshoku Haki?" Bui said in his usual disinterested voice, smirking at the glare Sanji was giving him.
"What that does have to do with anything?!"
"Plenty, it's what's weighing your leg down right now," Bui answered simply, laughing at the shocked look on his opponent's face. "Busoshoku: Koka to be precise."
"But… how?! Luffy can do this as well but it…" Sanji growled when he was interrupted by more bemused chuckling.
"Oh, did I forget to mention my disorder? How silly of me, fufufu," Bui's laughter was accompanied by Bui flicking a strand of his long black hair out of his eyes. "I was born with an unusual disorder that made me incapable of maintaining Busoshoku Haki around my body. It would simply leak off of me like running water."
Bui pointed at Sanji's invalidated leg with a sadistic quirking of the lips, his pupils shrinking in a deranged fashion, "It was while fighting a logia user that I learned what my condition truly allowed me to do. The poor fool was so confident of his victory before I blocked his nose and mouth. It's funny… you're starting to remind me of him."
His sudden flash of emotion died, his normal calm overtaking him as he walked closer to Sanji with his open-palm hand held outwards.
Sanji finally managed to drag himself back to a standing position and jumped away just as Bui's hand passed through the air he'd just occupied. Bui sprinted forward and swiped again, just touching one of Sanji's blond hairs as the other man ducked away.
Any relief that Sanji might have felt was short lived as Bui leapt forward so that he was almost floating level with Sanji's bent backwards body. The thin hand flew forwards and touched Sanji's chest, the heavy Haki overtaking him.
Sanji crashed into the ground, his leg swinging upwards and missing Bui, who rolled to the side. Sanji shifted back and forth, calling on all of his strength, but it all came to naught as he was trapped staring up at the clouds.
The next few moments seemed to be a repeat of the previous ones, Sanji's arms and remaining leg being encased almost as a formality. With those limbs taken care of, Bui slowly stalked the scowling Sanji.
"Stay back, you shitty bastard!" Sanji shouted which drew a bemused smirk from Bui.
"You're in no position to give orders," he pointed out as he reached out for Sanji's face, the only area not coated in weighty armour.
The chef pulled away as best he could but his eyes widened in frustration when Bui's finger trailed his cheek… a thin black streak following closely behind.
"I could so easily suffocate you… but to sully my hands on such unappealingly masculine features. What to do?"
Bui moved to cover Sanji's mouth, the chef's heart catching in his throat at the realisation of how helpless he was.
All hope seemed lost when a familiar arm spurted from Bui's shoulder to grip his wrist and held it firmly in place.
"Such a lovely hand, Miss Nico," Bui said in his usual reserved way.
Robin stood a few feet behind Bui's back, her arms crossed in a familiar position while a narrowed glare crossed her beautiful features.
"Step away from him," Robin said with a controlled tone, although the threat underneath was clear.
Bui smirked and stood back up, reaching across to grip the copied arm which quickly receded before his powers could interact with it.
"Seeing as I'm not quite ready for you yet, how about we strike a deal?" Bui offered, Robin's eyes glinting with a faint hint of interest. "I'll let him live and, in exchange; you'll come meet me tonight at the cave's entrance on the other side of the island."
Their eyes met, neither one portraying the slightest hint of fear or emotion as Bui asked, "Do we have a deal, my lovely?"
"Fine," Robin acquiesced, lowering her arms and approaching Sanji, Bui passing her on the way to fulfil his end of the bargain.
"Just after sunset, that's when we'll meet," Bui said, Robin humming noncommittally in agreement as the again emotionless man left.
She'd waited until he was out of sight to reach down and help Sanji into a sitting position.
"You can't take that deal! I won't let him hurt you!" Sanji argued, briefly forgetting his bonds and turning to face Robin.
The result was him falling back to the ground with a pained gasp as Robin chuckled darkly in her normal manner.
"I appreciate it, Mr. Chef, but you should worry more about your own injuries for now. They could still prove fatal."
The decision was soon made to return Sanji to the ship and see if Chopper could help remove the Haki restarints. Sanji and Robin started walking, Sanji's arms leant over Robin's shoulder and the opposite shoulder of her clone, naturally a position he was slow to object to. Still, he pleaded with her not to accept the other man's offer throughout the entire journey.