Sora was sweating bullets as he weaved around Ansem's attacks. It was nuts, first Ansem grows into a giant and then he fuses with a battleship Heartless the size of Monstro. As if that wasn't bad enough, Donald and Goofy were missing.
"Foolish child, do you now understand!? Darkness is all-consuming, all-powerful!" Ansem called out as dozens of giant bat Heartless seemed to materialize out of the seemingly endless void they were in.
Rather than respond to Ansem's Boast, Sora focused on the fight. "Getter Missile!" with that, Sora's jet launched a dozen missiles that wiped out all of the cannon fodder Heartless, though one of them veered off course and slammed into Ansem's ship and blew open an entrance. Seeing his chance, Sora dived right in.
It was a huge expanse of darkness even blacker than the endless abyss of darkness outside. Then he saw a pair of lights, it didn't take a genius to realize those were the thrusters of Donald's jet. The light from the jet's revealed that Donald was surrounded by giant, round Heartless with terrible, jagged teeth.
"Hang on Donald!" Sora fired his jet's machine guns, tearing the Heartless apart.
"Hey, I had them!" Donald quacked.
"Come on, let's find Goofy in here!"
"Right!" Their search wouldn't last long however as mere moments later, the void was lit up by the lights and sounds of more than fifty missiles going off in a very small area.
"Gawrsh guys, where've you been?" Goofy asked as he flew away from the carnage his salvo caused.
"We've been looking for you!" Donald retorted irritably.
"Anyway, we've got to get back to fighting Ansem, Donald get us out of here."
"Right!" Donald said with a twisted grin as the three jets moved into formation. "Change! Getter 2!" With that call the three jets came together, Sora's morphing into a pair of legs before attaching onto Goofy's which itself had compressed itself into a midriff. Donald's jet sprouted a pair of arms as it attached to itself to Goofy's machine, forming a humanoid robot. Finally, the combination concluded as the robot's left arm formed into a drill and the front of the jet expanded out to reveal Getter 2's eyes, forming a head reminiscent of Donald's old wizard hat.
"Thundaga Drill!" Donald called out as the drill was energized by the strongest thunder magic he and Sora could muster before charging straight forward at full speed.
"Gargh!" Ansem screamed in pain and confusion as Getter 2 erupted out of the Ship-Heartless with such blinding speed, that it took him a full second to fully register what happened.
The bat Heartless and the round-ones from the dark void all swarmed the Getter, but they could do little to stop it as it tore through every Heartless that approached with absolute ease. Conversely, however, it was doing little to reduce their numbers. "Drill Missile!" The still-energized drill shot off from Getter's arm, tearing through every Heartless in its path and very nearly piercing the core of the ship.
"Open Gett!" With that call from Donald, the robot split back into its three components. But it wouldn't stay separated for long.
"A hyuk, Change Getter 3" This time the one leading the formation was Goofy. Sora and Donald's machines came together and morphed it a set of treads, in addition to most of a torso, which came from Sora's jet. Goofy's jet approached at a perpendicular angle to dock into the torso from Sora's jet. For the finishing touch, Getter 3's eyes and arms sprouted out of Goofy's machine.
"WhirliGetter!" Goofy shouted as Getter 3's arms extended and the robot spun around clearing out all the Heartless that were up close. "Missile Storm!" Ports opened up all over Getter 3's body. Each of these ports fired several missiles in rapid succession. The empty void they were fighting in was suddenly illuminated by dozens if not hundreds of explosions. Each missile easily took the Heartless it hit directly as well those nearby, some missiles taking as many twenty targets. The barrage still wasn't done yet as over a dozen missiles that still hadn't detonated flew at the Ship-Heartless, exploding against a dome protecting the core, which was unfazed.
"Looks like we gotta get in close to take out that there core," Goofy said. "Open Gett!"
Now it was Sora's turn, "Chaaange! Geeettter! 1! Switch On!" This time, Goofy's jet formed the legs, Donald's formed into the torso and arms, and finally, Sora's draped over Donald's to complete the torso and from the head.
Getter 1 was a truly menacing figure, it's red, horned head with its shimmering emerald eyes, the razor-sharp blades on its arms, the flowing, blood-red cape, but most of all was the aura. The Getter 1 emitted strange green energy that seemed to frighten the lesser Heartless, but not Ansem.
With a furious shout, the face on the bow of the Ship-Heartless unleashed a massive torrent of dark fire. Sora scoffed. It was trivially easy for the Getter to get out of the way of the attack and to then fly alongside it. Getter increased in speed as it struck the face with a single kick, causing it to cave in.
"Getter Cutter!" Sora yelled as the blades on the robot's arms grew longer. It charged through the dome that Getter 3's missiles had failed to damage and broke through without difficulty. Before Sora could attack the core, a series of fleshy turrets grew out of the floor.
"Like that's gonna slow me down. Getter Ragnarok!" The Getter fired a dozen spiraling, magenta beams of energy that curved through the air and pierced through the turrets, destroying them all near-instantly. Turning back to the core, the Getter raised one hand.
"Getter Key!" A giant duplicate of Sora's keyblade appeared in the Getter's hand. Getter rushed forward and sliced through the core of the Ship-Heartless, destroying it.
Now it was time to get to Ansem. Getter quickly flew up to the very top of the ship, where the now-giant Ansem waited, attached to the ship by organic wires. Neither side said anything as they rushed each other. The Getter Key clashed against a halberd that greatly resembled the sword that Riku used in Hollow Bastion.
"Ahh!" Sora batted the halberd to the side, leaving Ansem wide open. "Getter Beam!" The Getter fired another magenta beam, hitting Ansem dead-on.
"Raggh!" Ansem snarled as the beam tore through his body, striking him in the stomach before exploding out of his back. "You will be devoured by the Darkness! Dark Firaga Blaster!" The Heartless emblem on Ansem's chest began to glow before launching a massive concentrated stream of dark fire.
The Getter was blown back and forced to drop its giant keyblade. Sora clenched his teeth as he felt his cockpit heating up, if he didn't act fast all three of them would be roasted alive.
"Getter Wing!" The Getter's cape wrapped around the front of the robot to act as a shield. That brief reprieve from the searing heat was all the Getter needed to escape. It rocketed upwards out of the torrent of flame, though its cape disintegrated as it did. This would have been a major issue if they had been fighting in a place with normal gravity since the Getter Wing was normally what enabled them to fly.
Now there was another problem, the Getter had lost its keyblade. The Getter Key had seemingly chosen the worst possible combination of the keyblade's attributes to inherit. He could only form one at a time but he couldn't call it back, it couldn't be wielded by anyone else, including Getter 2 or 3. Sora was just lucky that he found a different melee weapon at Hollow Bastion.
"Gettteer Tomaahaaawk! Boomerang!" The Getter pulled an ax out of its shoulder and threw it. It whirred through the air until it found its spot in Ansem's shoulder.
"Argh!" Ansem snarled as he worked to pull the ax out of his shoulder, leaving him oblivious to the Getter's approach until it punched him in the still-regenerating stomach. Seeing a chance, Ansem smirked.
Wiry tendrils of dark 'flesh' shot out from Ansem's stomach and wrapped around the Getter's arm. The Getter tried to pull itself free but failed. Ansem swung his halberd at the Getter. As the blade sunk into the robot's body, it spewed some dark-colored fluid from the point of entry, neither Sora nor Ansem knew what this liquid was, just that the Getter had lots of it. As Ansem pushed his blade deeper and deeper, both Sora and the Getter pushed back. The Getter pushed against the shaft of Ansem's weapon while Sora pushed back against the blade with his keyblade in his own cockpit.
"Rggh, Getter Cutter!" the sudden growth of the blades on the Getter's arms sliced the halberd in half, freeing up Getter's arm for another attack.
"Getter Tomahawk!" The Getter grabbed another ax and sliced through the tendrils keeping its arm trapped. Once it was free both Getter and Ansem back away from each other. As the Getter backed up, it grabbed its keyblade while Ansem was preoccupied with removing the ax from his shoulder.
"Getter Raid!" The Getter threw its keyblade at Ansem before firing a Getter Beam at it. The keyblade synchronized with the beam, empowering it and further accelerating it.
"Dark Firaga Blaster!" Ansem launched another stream of dark fire. Then it collided with the Getter Raid, and it failed instantly. The Getter Raid tore through the dark fire as if it wasn't there. There was no way for him to avoid the attack.
Ansem frothed as his face was locked into silent agony as he nearly ripped in half. He was ripped away from the Ship-Heartless which began to dissolve into darkness the moment Ansem was separated.
For a moment, Ansem was motionless, floating in the void. Then after a moment, he righted himself and began to look at a giant, stark-white door that Sora was pretty sure wasn't there a minute ago.
"It is futile, the keyblade alone cannot seal the Door to Darkness." He approached the door. "Kingdom Hearts! Fill me with the power of darkness…" The door began to creak open, billowing dark mist. "Supreme darkness!"
"You're wrong!" Sora shouted from his cockpit, "I know now that Kingdom Hearts is Light!"
The door burst open unleashing a massive burst of light. "Argh!" Ansem screamed as the light burned away at his skin, but it did not destroy him. That would come a moment later.
"Royal Burn!"
"Dark Breast Fire!"
Ansem was struck by two heat rays similar to his own Dark Firaga Blaster, one charged with light and the other with Darkness. Ansem looked through the door and saw two robots, one was the Royal Mazinger that belonged to that blasted mouse and the other was the Dark Mazinger battered and beaten from the past fights to the extent that it had even lost the enhanced form he had granted it. And of course, it was being piloted by his own vessel: Riku. But the two attacks still weren't enough.
"Kingdom Dynamic Special! Getter Beeeam!" Sora joined in a fired his own attack. The three attacks converged and finally overwhelmed Ansem, and he was completely destroyed. As Sora watched the spot where his enemy had once been to be sure that he was really gone this time, the Royal Mazinger called out to him.
"Now, Sora it's time to close the door for good!" The Royal Mazinger raised up its own giant keyblade, which had swapped colors from Sora's with a gold blade and a silver handguard. The Getter quickly changed to Getter 3 without fanfare. As Getter 3 pushed on the door as the Mazingers pulled, Sora and Riku saw eye to eye through their cockpits.
"Sora, take care of her." Sora simply nodded, he didn't know if Riku could see him but he was sure Riku understood.
And with a loud 'thunk' the Door to Darkness was closed, never to be opened again. As the Getter now stood alone in the void at the edge border of Light and Darkness, Sora saw a vision of Kairi, reaching out to him. Sora tried to reach back, but he couldn't. She just kept floating farther and farther away.
"Kairi, do you remember what you said before? I'm always with you, too." Sora said as Kairi drifted out of reach. "I'll come back to you. I promise!"
"I know you will!" Kairi replied before she disappeared completely.
In that moment, Sora was back where he had started. No, he realized, while it was true that he had to find Riku and Kairi again, it was different than when he lost them the first time. Back then when he lost his island he was alone, but he wasn't alone now. He had Donald, Goofy, all the friends they had made along the way, and of course, the Getter itself.
"Hey, Donald, Goofy seems like we've got a bit more to do before we can all go home," Sora said calmly.
"You've got that right, we've still gotta bring back the King!" Donald replied
"You know," Goofy said, "If Riku and the King are on the other side of the Door to Darkness, then there's gotta be a Door to the Light."
"Right!" Sora said with a nod, and the Getter went off in search of Riku, King Mickey, and their Mazingers.
Here we are. I don't really have anything to say really, I wrote this on a whim just to express the idea of 'KH but mecha' which also means I haven't put any effort into editing or revising this. So enjoy this raw slice of my imagination.