Spoilers from included and/or represented works abound. Please read this fiction carefully.
"Behold, the Last Zero! I'm your omni-ruler, destined to rule all of the omniverse!" Genjitsu-no-Omnia declared. "All realities, including what should be the last, all will kneel, and bound to me!"
The residents of the Last Reality, the Storm King included, all bowed to Omnia, much to the entire alliance's (and CXA's) disgust. *island-ship flips back*
"Hey, you!" Reimu Hakurei and Marisa Kirisame defended the alliance. "Enough omniversal snitching!"
"What do you want?" Omnia noticed. "If you don't obey, I shall execute all of you!"
"This is your last chance, the old king and queen." Omnia briefly targeted the Origin and the (Cube) Queen... "And you too, that herald."
"Hey, what if I don't approve?" Ariana Grande questioned Omnia. "You wanna rule with iron fist or something? Yeah, not gotta happen."
"You!" Omnia quickly Force-choked Ariana Grande from afar, and rises her up. "You happily stole my original powers, and you banned me without ever thinking about it!"
"You're a pathetic celebrity." Omnia crushes out, killing Ariana Grande. "You cannot grasp my true power."
Then she throws the now dead celebrity down to where some Cube monsters are, who proceeds to devour and tear the corpse. All, much to the horror. Omnia retrieves the powers in form of a rift butterfly containing the powers would made the Goddess of the Rifts.
Sheath screamed!
"If you're with me, perhaps I can spare you, as you serve me." Omnia offered to the alliance. "If you don't..."
She crushes the butterfly, receiving the powers she lost, and transformed. Restoring the deep gradient Geno remembered of, and the white hair becomes iridescent and untied, long and flowing. Her right eye becomes a gradient of blue, magenta and purple, symbolizing the Zero Point being accepted when Ariana Grande became the Goddess of the Rifts. The cybernetics remains in place, but she dons a variation of what the Herald normally wears, but with ornamental shards made of rifts (much like Ariana Grande during the Rift Tour) around it.
"...you will be executed." Omnia returns to her original body, but keeps all the upgrades. *relief sigh* "Feels good to be back to shape."
Everyone gasped at the sight. "The Rift Goddess!?"
"I can finally abandon the name 'Genjitsu-no-Omnia', what placeholder do you expect?" The Rift Goddess realized.
"You're a deity from the Last Reality!?" Agent Jones questioned. "That means the likes of the King and the Queen are all gods there!?"
"Our definition of such trivial terms is so different, we usually omits it." The Rift Goddess clarified. "That being said, I have since transcended continuously."
"Everyone, the only hope of survival is to Cross All!" Reiji told everyone. "Unite!"
"Your unity doesn't change anything I suggest." The Rift Goddess replied. "Serve me or begone."
"In the name of Zero Point..." David declared. "We'll kick your ass and save the reality!"
The alliance shouted in their stances to save the omniverse, in absolute defiance of the Rift Goddess herself. This broke most of the residents of the Last Reality, including the Storm King, Joey the multi-agent, and Bloom, with they suddenly realized something.
"And even I realized that your irresponsibility and brashness has caused you to go to a path that's driven you insane." The Queen concluded. "Therefore, you're the one who should be executed, not us!"
"Very well, you really did decided to seal your true fate." The Rift Goddess took note. "Then I shall execute you all right here!"
The Rift Goddess rift her mind, and with that, summoned a meteor rain towards the island-ship, damaging the shields.
"She's too powerful!" Captain Velvet Meteor shouted.
"Do something, the Hegemonies!" Rebecca scolded the Hegemonies.
"Very well!" Margueritte Breuil then proceeded to chant.
"No, I can taste your terror, child. All that anxiety and doubt in secret... it's delicious." The Rift Goddess sadistically fires an rift-power energy blast in front of the Marie, interrupting her andintentionally missing just to startle her. "Give in to your fear. Flee, screaming, and I'll give you the most painless, peaceful end." *evil laugh*
David heard it, and activated Sandevistan, pushing Goddess Marie away, then blocked the illusion with the sword, crashing it.
"You have Phantom Ruby?" David mocked the illusion itself.
"Destroy all of them, my-" Omnia went mad...
A fireball from the miniature Collider threw by the Mecha, knocking Omnia off.
"Oh, fuck, no!" IF screamed. "We need to seek a way out!"
giggles* "All the powers l acquired before this moment not only combined into my own masterpiece myself, but otherwise those combined is no more a challenge than a crippled, dying shaggy dog." The Rift Goddess relished in all her powers. "As I have imagined, my original power liberated is without peer nor opposition. It's the ultimate power!"
The Rift Goddess remotely set the cavern in the island-ship aflame, in flames of Amaterasu, with a literal blink of an eye.
"Ah, and still more lowly resistance incoming." The Rift Goddess noticed any signs of resistance incoming. "I've been waiting for this moment to negate all oppositions you hope to bring up."
"Tell us what else you intend to do with the Zero Point!" The Foundation angrily asked.
"I already consumed it so many times, it is of no consequence against me." The Rift Goddess dismissed it. "Operation: Zero Hell is a success, and you still spout such nonsense."
"Zero Point helped making the omniverse it is." The Foundation counterargued. "The only thing of no consequence of around here is the Nothing."
dismissive giggles* "Ah, I suppose you would think so." The Rift Goddess dismissively replied. "Oh yes," *evil laugh*
"I am the Rift Goddess, transcended by Zero Hell!" The Rift Goddess properly introduced. "You think you do not care, and yet you come all the way just to confront me."
"To you, I have become another anomaly to you, the seven you are, the IO, and that stupid celebrity I just left to be devoured." The Rift Goddess continued.
flashback to the first time...*
"You're the Rift Goddess!" Geno spotted the Rift Goddess. "Catch her!"
"I already killed your people, and why do I care!?" The Rift Goddess lashed out.
"You takes rift and do things with whatever you rips off, right?" Geno guessed.
"This really is as close as you can guess." The Rift Goddess spit out a rift bolt, blasting Geno off, gorily wounding him.
"Argh! You...! How could you...!" Geno is severely injured and bleeding.
The Rift Goddess escaped.
Later...
"Firstly, you reminds me of the Cube. It devours, and I don't wanna let the reality fall because of it." The (former) Cube King, now the Origin, argued. "Secondly, you are too ridiculous, lashing out so much that it causes problems wherever you go."
"And finally, you seems to be losing grip of your sanity, from the look of it." The Origin concluded. "But due to your reasoning to go rogue, you're not welcome. Get out, now!"
The Origin punches the Rift Goddess and flew away alongside the rest of the Seven.
Later...
"You're the same one who screwed the aliens from the Last Reality over a trivial incident?" Ariana Grande bans the Rift Goddess, as the former recently got the latter's power. "That proves you're not worthy anymore. You're banned!"
"Worthless now." Ariana Grande kicks the fallen Rift Goddess out. "Don't show your pathetic face around us ever again."
Later...
points gun towards her* "Sorry, but I never loved you. In fact, you're too suspicious for me." Agent Jones avoids the fallen Rift Goddess. "Get out, or I ahoot you!"
Then, she snapped.
"I... I'm lost... me!?" The fallen one is shocked. "I can't be loved... neither believed... nor trusted... anymore!?"
"Urgh, pathetic, unworthy!?" The fallen one is ridiculed. "Me... they're... mistreating me!?"
"No! This can't be! This... this can't... this can't be!!!" The fallen one go insane. "What did I do to you all!?" *screams*
And so, the fallen one go to the alternative version of Reality-616 (which is mainly Earth-616) and stole a complete Infinity Gauntlet, then hopped realities and traveled through space-time and stole powers (just like Hirume and Yomi described nowadays), until her original body started deteriorating, all in just a year. So she resorted to absorbing herself into Najimi Ajimu (from a timeline where the Ajimu alway won because of her powers) and built up the powers, changing the bodies per roughly a dozen cycles, where each cycles is worth a year of travelling on her part. Making that a matter of time before she's able to make Zero Point explode all by herself, and that was all just the beginning.
Back to the present, as she recounts her experience so far...
"From the moment I went haywire by the Islanders and the likes, I gave in to my own reasons and stole powers." - "And I let go of the old me, the one that not welcomed by island or Last Reality, so that I could embrace the new loops and become stronger. And then, at last..." - "I got enough power and destroyed the Zero Point so bad, it cannot auto-fix itself anymore, letting me obtain its power alongside all, the power of creation to make all yield to my will!" - "I... was... reborn!"
The alliance is shocked at the actual backstory: not only it matches what the Hegemonies, Geno and the CXA described, but it also serves as a revenge against both the island and the Last Reality, as well as its inhabitants and visitors alike.
"I've only become what I am because of your mistakes, yet none of you truly cares." The Rift Goddess told the Mecha crew altogether. "But I suppose that's the way it goes. It simply means that the original me was to ridiculous, too pathetic to be cared about."
"And now, you've become nothing more than atoms, waiting to be vaporized by the force of cosmos itself." The Rift Goddess continued. "Thanks to all the limitless powers I have obtained countless of times, I have become literally unstoppable!"
"Take this!" The Rift Goddess summoned a rift to suck the entire Mecha in just inside the cockpit. Cue the panic of the majority of the alliance.
The Mecha fell down to the Ice Moon, and that place now... seems off.
"Ngh!"
The Mecha then got up, and the crew is forced to recalibrate.
"Urgh... What? Where?" Geno is fuzzy. "We're in... Ice Moon? No, so much wrong..."
Piles of bodies surrounds the Mecha. Notably, among them are Emily Moonthistle, Koshirae Tsurugi, Master Blue (Ryusoul), Bytes, and even... Singularity, who's currently an AI inside the Mecha.
"No... my body..." Singularity saw it.
"My warrior! What have she done to him!?" The Herald isn't happy about it.
"This should be called Icy Paradox. Ice Moon stick in the continuum." The Rift Goddess telepathically contacted. "I didn't expect you to survive this, but you must admit, it was truly interesting, wasn't it?"
giggles* "Oh, all the powers, just after I got all mine back!" The Rift Goddess gloated. "Just as I thought, it's unrivaled! Or dare I day, unrival-able!"
"Not even omnideities will be able to stand against me now!" The Rift Goddess laughed in evil notes.
"You're gone over the edge now, times infinity!" The Queen lashed out.
"What are you plotting, that stupid goddess!?" The Herald questioned. "Stop! Where do you think you're going!?"
The Rift Goddess laughed, then the voice cut off.
"This is unbelievable." The Paradigm becomes sad. "Everyone's now in danger."
"And those dead bodies..." The Foundation found out. "Those fallen individuals of all kinds..."
"We can create a rift for ourselves and get out." Agent Jones suggested.
"No, she would just force us into here again and again and again." The Origin refuted.
"So we're effectively stuck here." The crew realized.
A mysterious blonde woman in beige dress passes by, and the Mecha just looked.
"Who are you?" The crew has no idea.
"I'm Schala 'Kid' Zeal, a Radical Dreamer." The woman introduced herself. "Why do I experience all the time crashes all at once."
"Why are you here, Ms. Zeal?" Agent Jones asked.
"Because Larvos... an massive army of Larvos, everywhere in the timelines, threatening multiverses..." Schala revealed.
"We're all stuck here. Can you help us do something about it?" Geno asked.
"Chrono Cross, the song that unites... wait a second..." Schala realized something. "Who ruined the timelines?"
"The Rift Goddess, who I decided to exile because of her irresponsibility." The Cube Queen revealed.
"Oh, I see..." Schala realized. "That woman who drowned Serge long after the story is told..."
"Drowning... what? You're saying about the timelines being ruined, involving drowning that man again?" Agent Jones noticed.
"Yes, when he was trying to find me-" Schala confirmed-
"Watch out!" The Herald chromed Schala.
A meteor strike directly at Schala, spite out the Mecha and seemingly crush her. However, turns out that the Chrome blob is very much fine, and she emerged unscathed.
"What? What's this? Why am I... liquid?" Schala has no idea.
"Phew, that's the Chrome, morphing substance I use." The Herald explained. "You don't find such substance in your world."
Schala looked at her metal-like body for a while, and is surprised.
"Chrome don't get damaged so easily." The Herald responded. "Be glad I covered you with that."
"Paradoxes and timelines scattered everywhere around here." The crew noted. "Go in, and we'll discover."
Schala agreed, so she went inside the cockpit. The Mecha walked around, discover various things ripped from several timelines, not just from the island and all its incarnations, but also from several other worlds, such as the remains of the Centipex, the arena of Oscar's Super-Bowl, various Llamas floating around, the remains of the Progenitors, the Digital Worlds' fragments, the spirits (Smash Bros. Ultimate) floating around, various Ruins Guards and Honkai Beasts among the piles of bodies, etc. All kinds of landmarks from so many worlds floated wastefully.