Rescue
Luffy ran down the underground passage Chimney and her rabbit had showed him, Fox at his heels. The white-haired woman hadn't commented on his dashing around all over the place, though she had stopped him from trying to sail across the whirlpool-filled water separating the Tower of Justice from the Bridge of Hesitation. Instead she had kept up with him, always a pace behind, singing a little ditty under her breath. Luffy had picked up something about the ankle bone being connected to the leg bone and lost interest, though the tune was fairly catchy. He'd heard her singing about blood, the Grand Line and the Yonko earlier and he intended to have her sing him the whole thing later. He hadn't known she could sing; she'd never said she was a musician.
"Rooobin!" he shouted as he dashed down the corridor. "Robiiin!"
Behind him Fox broke of her singing to chuckle. "Blackbird heard you," she told him. Encouraged, Luffy picked up speed and came to a door blocking the passage.
"Doors? It doesn't look like steel this time," he noticed. Without breaking stride he kicked them hard, smashing them open and across the open space that opened up behind them. Blinking, Luffy looked around. "Where am I?"
"Welcome."
Luffy looked at the speaker and pointed an accusing finger. "Ah! Pigeon Guy!" He was about to attack when a Den Den Mushi rang and Fox placed a warning hand on his shoulder.
"It might be important," she advised him as the Pigeon Guy produced a baby snail and it started talking.
It didn't sound all that important until Luffy recognised Robin's voice. The following conversation went mostly over Luffy's head, but he knew Fox was listening carefully and trusted her to tell him if he needed to act on any of it. "Where was Robin speaking from?!" he demanded as soon as the transmission finished.
"… Behind this door," Pigeon Guy told him. Luffy charged, but was rebuffed. "'I can't let you pass'. At least let me say it," the man added as he parried Luffy's punches. The fight lasted a few more seconds until one of the rubberman's punches connected with one of the Pigeon Guy's and both were blasted back in opposite directions.
"Back off," Luffy said, climbing out of the wreckage, "Robin's behind that door, right?"
"She's there all right, but you'll never see her again," Pigeon Guy taunted.
"Captain?" both men turned as Fox dropped down to land next to Luffy. "Fox will take your hat," she said, lifting it from around his neck, "and find Blackbird. When you have beaten Kitten you can catch up and get your hat from Blackbird."
Luffy nodded; Fox was fast enough to get past Pigeon Guy and strong enough to look after Robin. "Go," he told her, charging his opponent.
Fox vanished, Pigeon Guy tried to move in front of the door but Luffy got to him first and slammed him head-first through the floor. The door disintegrated and Luffy saw his 'master of disguise' wave the straw hat cheerily at Pigeon Guy as he rose from the rubble.
"Bye-bye Kitten; don't lose too badly!" she cooed, raising a glowing hand. Pigeon Guy ran towards her again but the destroyed door reassembled itself in an instant, blocking the way, and Luffy attacked the agent once more. He had to win! His nakama were counting on him!
Robin had tried to escape Spandam; having realised she really didn't want to die encouraged her to do everything she could but the cowardly man had sicced his elephant-sword on her then beaten her up. She couldn't fight back very well with Kairoseki cuffs on her wrists and he had resorted to dragging her up the stairs by her hair. She was still resisting as much as she could when a familiar straw hat floated down from the ceiling to land in her lap.
"Whu-" Spandam was cut off by a flying kick that caught him under the chin and hammered him into the central pillar of the spiral stair. Robin crashed sideways, staring first at the hat in her lap, then up at Fox, who was pulling on a pair of studded leather gloves.
"Fox likes weapons best," she said conversationally, "but when dealing with Scum, all one needs are good gloves and elbow grease!" she threw herself at the head of CP9, ripped his sword away and laid into the wailing man with vigour. A few highly enjoyable –for Robin– minutes later Spandam had passed out under the onslaught and stopped whimpering, so Fox got off him and hurried over to the archaeologist.
"Fox has no keys," she confessed, digging in a pocket, "but Fox has lock picks. Sit still, Blackbird." The assassin knelt behind Robin and set about fiddling with the cuffs.
"How are you even touching them?" Robin asked. Fox was a Devil Fruit User.
"Gloves are good for lots of things," Fox said absently as the cuffs clicked open. "Here," she handed Robin Spandam's Devil Fruit Sword. "Fox will carry the Scum; the only way out is forwards."
"Why are you bringing him?" Robin asked, accepting both the blade and the sheath Fox had removed from her former captor's person.
"Fox might want to kill him later," the slightly taller woman said honestly, "or Fox might want to see how many more bones she can break before it happens naturally. Fox has not decided."
Robin couldn't actually find fault in her crewmate's scheme, so the two women continued up the steps towards the bridge of Hesitation, Luffy's straw hat perched jauntily on the archaeologist's head. Robin smiled; she was happy.
Fox walked calmly along the bridge of Hesitation, Robin beside her wearing Luffy's hat and tears streaming down her face. Fox would have been worried were it not for the ridiculously wide smile plastered across the archaeologist's face and the fact that she was chuckling 'shishishi' under her breath as she staggered along beside the assassin. Fox knew that the boat at the other end of the bridge would be full of Marines, but wasn't too bothered. One problem at a time.
As they neared the end of the bridge Fox swung the still unconscious body of Spandam onto the ground and loosened her swords in their sheaths. "Seagulls will see us soon," she commented, "if they haven't noticed already that something is wrong." Robin nodded, touching the hat on her head before settling into one of her preferred stances.
The two women waited, Fox listening to the sound of orders wafting up from down below as the marines prepared to head onto the bridge to find out what had happened to Spandam.
"Hey!" Fox did not look back, but Robin did.
"Franky?" she muttered, just as the Marines stormed the archway.
Fox could not use her Devil Fruit powers in this crush; Robin would be using her Ability as well and there was no guarantee that Fox wouldn't graze one of her detached limbs. So instead the woman in the black hat limited herself to pure swordplay, singing the song she's been thinking about since entering the Tower of Justice:
"Dem bones dem bones dem live bones,
"Dem bones dem bones dem live bones,
"Dem bones dem bones dem live bones,
"Now come apart by ma sword!"
"Your toe bone connected to your foot bone,
"Your foot bone connected to your leg bone,
"Your leg bone connected to your knee bone,
"Your knee bone connected to your thigh bone,
"Your thigh bone connected to you hip bone,
"Your hip bone connected to your back bone-" fiery explosions rained down on the marines around her, driving them back down the steps towards her ship.
"What was that?" shouted a Marine officer.
"We cannot identify the shooter!" Another Marine shouted.
"There!" cried a third Marine, miraculously unscathed and holding a pair of binoculars, pointing up at the top of the now very wobbly Tower of Justice.
"I've come with the keys!" Franky shouted as he drew level with the women. Then he noticed Robin's hands were free. "Wait… did your key work?"
"Fox had lock picks," Fox said simply, not taking her eyes from the now decimated Marine force.
"What?! You mean we could have not bothered!" Franky roared. Fox raised an eyebrow at him.
"Silly killer-people needed beating and the crew needed to take out their frustrations on somebody. Fox made sure Blackbird was safe; what else matters?"
Franky produced a baby Den Den Mushi. "Guys!" he said into it, "Fox had lock picks!"
"WHAAT?!" came the outraged chorus of replies. Fox giggled.
"Did you win?" she asked the snail.
"Well yes, but-"
"Blackbird is safe and the enemy is defeated," Fox overrode them implacably. "Come and catch up so we can leave."
Badooom!
The part of the iron fence surrounding the island in front of the now wide open Gates of Justice exploded. Fox glanced past her opponents to see warships approaching in the distance. "Fox hopes they hurry up," she said aloud.
"So do I," Robin agreed, fingering her borrowed hat.