Fire
When donning the mask Fox lost all sense of time: there was the mission and nothing mattered but the mission until the mission was complete. She didn't get tired, so time was meaningless. The Phantom had evicted Sengoku from the execution stand twice more already, stuck more Kairoseki needles in both Aokiji and Akainu and dismembered at least two dozen Vice-Admirals and other miscellaneous underlings who had tried to assist their superiors. Garp had been conspicuously absent, probably because he cared about Ace and it was very obvious the assassin was protecting him. However it was getting difficult to do so and the Phantom was considering cutting her charge loose. On the one hand, he'd be harder to protect while running around. On the other she wouldn't have to focus so hard on keeping him safe as he was a Logia user and most attacks would go through him.
Decisions, decisions. The Phantom barely paid any attention to the steel walls blocking off the bay; they didn't matter. The mission was to protect Ace and Ace was being protected.
Then Luffy landed at the base of the stand in front of the three admirals –Kizaru was there but not really joining in much after losing half his leg muscle– holding tightly to a wooden spar that had been thrown over the barriers. The Phantom did not join in the battle against the admirals, simply defending the stand and cutting down everyone who got too close. The small space at the top of the stand belonged to the assassin now and the blood and body parts that rained down after every attempted assault proved that possession was indeed nine-tenths of the law.
As the tides of battle shifted and the Whitebeard Pirates made it up onto the island the highest ranking Marines shifted from trying to take back Ace and the execution stand to intercepting any pirates trying to join the assassin at the top. The Phantom did not intervene so long as they stayed out of sword range; Garp punched Marco the Phoenix in the face mere yards from where the masked killer was poised over the chained pirate without the assassin moving a muscle.
The Phantom paid no mind to the tears of joy being shed by the object of the mission, waiting patiently for new orders or a change in circumstances. Deep inside, well buried by artificial calm and an iron sense of duty, Fox noticed that Luffy was dipping deep in her reserves again. Not that it made a difference right now; she could have sustained every last pirate fighting while in full Logia form and done so for days at a time. Being a Logia meant limitless access to your element and her element was 'Life'. The Phantom Fox could outlast every last Marine being brought to bear; time meant nothing.
So the assassin waited on as Whitebeard charged and his Division Commanders started to run into difficulties.
Ace stared down at the scene unfolding below, having by now got over the shock of the white watchdog Luffy had somehow set guarding him. Pops was wounded and bleeding and had just coughed up blood, his illness catching up with him. Fire Fist was no longer kneeling on the edge of the stand but sprawled on his stomach under the feet of the assassin protecting him but didn't care for the indignity of it right now. He was too worried about Whitebeard, who had just sent another dozen men flying.
"I am Whitebeard!" the old man roared. "My death: its significance is not lost to me and I am well aware of just what that would entail. That is why, the very reason why I cannot die just yet. Not until I can secure the future of my sons with these very hands! Isn't that right Ace?"
Ace stared, even as another wave of determined Marine Commodores mounted the stand and were smoothly dismembered by a blade that sang like the rushing of ocean waves. He ignored the blood that drenched him and flying body parts bouncing off his back to fall at the edge of his line of sight; Luffy was on his feet again.
"Ace! I'm coming now!"
"Men!" Whitebeard roared as Luffy dashed forwards. "Use all you've got to back up Straw-Hat!" Some of the green-coated fighters who had to be Spitfire's crew –not that she even had a ship but 'minions' didn't fit– joined in the rush, some of them having discarded their boots to reveal fins or webbed feet. Now that the ice was mostly gone there were water blasts flying as well, driving the Marines into buildings and bringing down masonry. Ivankov ran beside Luffy and Ace' fellow Division Commanders backed his little brother up then Inazuma of the Revolutionary Army emerged from Ivankov's hair and cut a road to the execution stand.
Luffy dashed up the oddly shaped masonry towards Ace and his guard dog, who appeared to be more interested in the Admirals down below than the fast-approaching pirate.
"I'm here! Ace!" Luffy bellowed.
"Go Straw-Hat! Free Ace!" came up the chant from down below. But then Gramps landed on the road, blocking the path a good distance below the Phantom's reach.
"Since long before you were born I've been fighting with pirates!" Garp roared, the bridge cracking beneath his feet. "If you want to get through here you'll have to do so after killing me, Straw-Hat Luffy! That's the path you two have chosen!"
Ace winced; Gramps really was Luffy's grandfather by blood and that was an impossible choice for his little brother. Family was family.
"I can't do it Gramps!" Luffy shouted, not slowing. "Please move!"
"If you can't do it that simply means Ace will die!" Garp shouted back. Ace tensed as a bloody boot entered his field of vision, placed deliberately above his right shoulder. The blood flowed down the leather onto the stand, revealing pristine white underneath as Garp charged Luffy with a fist out and Ace' little brother crouched, smoke rising from his body again.
"Uwaaa!" Luffy screamed, his fist hitting Garp in the face and sending him flying as he dashed up the crumbling bridge. He landed on the slick execution stand and almost stumbled, but righted himself quickly.
"I have the key!" he gasped. "Hold on-" A push from the assassin dropped Luffy onto Ace' back as Fleet Admiral Sengoku landed on the execution stand, massive and golden and very angry. The Phantom Fox stood poised between the leader of the Marine forces and the two pirates, sword sheathed in his sash and garments as white and clean as though they'd never been bloodied.
A flash of light caught Ace' eye as Luffy fumbled the key into the lock, ignoring the stand-off occurring scant feet away.
"Ah! The key! The key's been ruined!" Luffy squawked. The assassin turned, leapt back a step and grabbed Luffy by the shirt, turning him to face the Fleet Admiral's attack. Ace was kicked sideways on his face once more as a gloved hand dropped to the slick boards by his ear and a wicked hum like a metal tide danced over his back.
Shwuuum.
The cuffs fell apart as the execution stand crumpled; Ace instinctively activated his powers and reached for his little brother, who had somehow blocked a punch from Sengoku the Budda by turning into a balloon.
"You've always been this way Luffy!" Ace growled as he caught his brother by the back of the shirt, "never listening to a word of what I say and always overdoing it!" He used his Mera Mera no Mi ability to cushion their fall, floating on the heat of conjured flames. Beside him the white-clad, fox-masked assassin fell too, his short cloak buoying him up until he landed lightly at Ace' back and to Luffy's right on the stone paving of the Plaza.
"Can you fight Luffy?" Ace asked.
"Of course!" Luffy protested. "Ghost-guy, watch our backs!"
The assassin sharply nodded once, hand floating over the hilt of his sword as he watched the gathering Marines. The fight quickly started up again, Luffy's assassin associate coordinating with them both perfectly as he cut down Marines in between Ace setting them on fire and Luffy sending them flying.
Whitebeard's voice echoed over the battlefield, catching Spitfire's attention.
"We've done what we came for; now there's no more reason for us to be here! What I'm about to tell you is my final captain's order: listen carefully, Whitebeard pirates!"
Spitfire couldn't pick words out of the cacophony that followed, but she could tell the old geezer's crew wasn't happy. She waded through the melee towards the man, cutlass swinging from one hand and the other snatching up people and throwing them around.
"This is where you and I split up!" Whitebeard bellowed. "Every single one of you! Stay alive at all costs! Return to the New World in one piece!"
A sentiment Spitfire could get behind; she whistled for her pets, Runt in particular who had to circle the island to get here. "Time to go boys and girls!" she called out to her people, who all responded at once, including the two wearing badly damaged Marine uniforms.
"I'm a remnant of my era!" Whitebeard continued. "There ain't no ship that's going to carry me out to the new one! Go on! All of you bastards!" The massive fortress overlooking the harbour trembled and shattered. Spitfire grinned.
"To the sea, kiddies! Last one's a rotten egg!"
As Whitebeard made his announcement Ghost-guy grabbed Ace firmly by the shoulder and steered him down towards the sea, beckoning to Luffy as he did so. Luffy got the hint, hurrying after them amongst the mayhem and panic. As they passed Whitebeard his big brother pulled away from the assassin and set up a massive flare, kneeling. The old man turned.
"No need to speak," Whitebeard said. "Just answer me one question Ace: am I a good father?"
"Of course!" Ace choked.
The old man chuckled. Ghost-guy stepped forward again and pulled Ace to his feet, headed for the ships.
"Running away the moment you grabbed Ace, what a bunch of cowards, the whitebeard pirates," came an unfamiliar voice from behind them. "The captain as well; it can't be helped. Whitebeard is after all just a failure from the previous era!"
Ace stopped, shaking off Ghost-guy's hand and turning around. Luffy stopped too.
"Failure?" Ace repeated softly. Luffy noticed that the assassin he'd been lent seemed to want to interrupt, but didn't. Was it because he'd only ordered him to stop anyone from killing Ace, then to watch their backs? Should he ask him to drag Ace along with them and escape? He knew this Phantom-guy could teleport; he'd seen it on Alabasta.
"Take back what you just said!" Ace hissed at the Admiral with lava sliding down the side of his face. The Admiral did not but went on speaking, riling Ace up further and insulting the Whitebeard Pirates with every other sentence as things descended into a shouting match and Ace threw a punch.
The clash threw up a fountain of lava and Ace screamed in pain. Luffy staggered, his strength running out again. Ghost-guy shoved him at Jinbe then hurried back towards Ace, then everything happened at once:
Luffy dropped the Vivre card Ace had given him and bent over to pick it up.
The admiral lunged at Luffy, lava fist raised.
Ace screamed his name.
Luffy looked up to see the admiral's fist sticking out of his big brother's chest and on the stones by his knee, the vivre card crumbled.
Then speed somehow returned to normal, a white blur striking the admiral in the face and launching him backwards into the air. A furious shriek echoed and a massive woman with green hair wielding a wide sword charged after the admiral, sea water dancing around her bloody fist. Luffy stared in horror as the Phantom wrapped his arms around his big brother, lifting him into a bridal carry so that his head rested on the assassin's shoulder, uncaring that his cloak had caught fire.
"I'm sorry, Luffy," Ace coughed up blood all over Ghost-guy as Luffy staggered closer, staring in horror at the hole that when right through his brother.
"Ace we've gotta hurry and treat your-" the rubberman begged.
"I'm sorry I couldn't let you save me properly," Ace went on, coughing up more blood as more red streamed from his abdomen. "Forgive me!"
"Somebody save Ace!" Luffy begged frantically as the Phantom's arms tightened around his big brother, supporting him.
"It's no good," Ace panted. "I can tell when my own end has come! He's burned up my insides!" he gasped. "I'm not coming back from this, so… Luffy-"
"What are you talking about Ace?" Luffy begged. "Ace… are you going to die? You are not going to die! No! You promised!"
"I don't want to… Luffy," Ace chuckled, the sound having a horrible sucking undertone. "But-" he trembled, gasping for breath and slumping forwards.
"Ace!" Luffy screamed, suddenly seeing the almost destroyed Vivre card and turning on the assassin, the assassin who knew Fox. "Ghost-guy! Don't let my brother die no matter what!"
Ace gasped, then the air rattled in his chest in a terribly final way and his eyes closed. The assassin vanished in a ball of white light just as the paper on the ground fell apart to nothing. Luffy choked, staring in horror at where it had been.
"Aaaaaace!"
And that's the end of the battle for both Fox and Luffy.