The Galaxy Cauldron was the birthplace of all things--the holiest place in the universe. Its existence became a double-edged sword, however, when Chaos, pure evil given form, inhabited it. All evil was effectively some aspect of it, including Queen Metallia, Wiseman, Pharaoh 90, Queen Nehellenia, and Queen Galaxia.
The only way to truly defeat Chaos was to destroy the Cauldron it inhabited and sacrifice everything. Life would cease to exist and no more stars could be born, but at least Chaos' reign of terror would also end. Mortified by that unconscionable choice, Sailor Moon did the unthinkable and dove into the Cauldron, taking Chaos with her via the Silver Crystal's enormous power. She dove in alone, but her comrades--her dear friends--were right by her side in spirit as she descended.
She drew upon the power from every Sailor Crystal and her own Silver Crystal within the Cauldron to unleash her most powerful attack against Chaos: "Silver Moon Crystal Eternal Power!"
In a sense, Sailor Moon sacrificed herself to do so. However, the Sailor Crystals throughout the galaxy bound together into a single Cosmos Crystal, capable of harnessing the Lambda Power. That power caused Sailor Moon and the other Guardians to be reborn and reunited within the Cauldron.
The spirit of the Cosmos Crystal asked what Usagi and company's intentions were. She responded without hesitation that they wanted to always live together, no matter how difficult it proved to be. The spirit granted their wish and sent her and her fellow Guardians on their way.
Usagi (now referring to herself as Serenity, since her daughter-to-be would be named Usagi) and Mamoru later married, with all their friends in attendance--save for the yet-to-be-born Chibiusa. Their marriage was later considered to be the start of the second Silver Millennium. There was the threat of Chaos eventually returning, but naturally, no one wanted to spoil the happiness of the moment with concerns about the potentially distant future. The Sailor Guardians still wielded the Lambda Power. Even newborn Usagi possessed it at birth. They were all confident that any new threat that arose would be handled with ease.
Decades later, Chaos still hadn't reappeared. The Sailor Guardians had stopped aging at their prime--around their mid-twenties. Haruka and Michiru got married themselves, as did Ami and Makoto, and Usagi and Hotaru. Rei and Minako became friends with benefits, often indulging in polyamorous fun with the other Guardians.
Before long, things had finally settled down. Life went on.
Upon their marriage, Haruka and Michiru decided to combine Miranda and Triton Castle (more commonly known as the smallest satellite of Uranus and the largest satellite of Neptune) and give it its own orbit between the two planets--a feat made nearly effortless, thanks to the Lambda Power.
Their castles (and those of the other Guardians) possessed enormous power--enough to allow Sailor Moon to transform into Eternal Sailor Moon at one point. As such, the combining of the two, coupled with their residents' Lambda Power, resulted in an exponential boost to both of their powers.
As they finished doing so, a large, erect cock about as long as her thigh materialized between Uranus' legs, accompanied by a surge of pleasure, causing an abrupt moan from her. Startled, she raised her skirt and examined the new appendage. It had punched through and tore open the bottom of her leotard.
Neptune was undeniably surprised. "Haruka, is... is that thing real? Where did it even come from?"
"I... I'm not sure, but..." She started panting. "Oh man... I'm losing my mind here! It's all so alien, and yet so... right, if that makes any sense. It's... kinda like I've always wanted this... and now I finally have the opportunity for that release. Michiru... would you, ah... mind helping out?"
Neptune stammered, "Certainly, but I'm afraid I'm not very well-versed in these matters." She dropped her skirt and moved the bottom of her leotard aside, then moved towards the tip of the pulsating phallus.
"Watch out!" Uranus groaned. Neptune instinctively hit the floor, just before Uranus' cock violently quadrupled in length and girth.
Neptune rolled over and stared in awe at how much larger it was now.
"Oh... my..." she whispered. Her sex drive was very much under control--something she was proud of in adolescence--but now, staring at her lover's gargantuan cock, she couldn't help but want all of it inside her, laws of physics be damned.
Meanwhile, Uranus was starting to have trouble standing, both from how absurdly large and heavy the appendage was getting, and also the sheer amount of raw desire and lust rolling through her shivering body.
"I had very little warning before that happened," Uranus said. "Honestly, it's not safe for you to be there. I have no idea when it'll grow next, or by how much!"
"But you're so pent up!" Neptune cried after standing up. "I can't bear to just leave you in agony like this!"
"Oh, believe me, I know! But I don't want to end up hurting you by accident!"
"Well, what should I do, then?"
"I can barely think like this! Please do your--" Uranus screamed as her cock grew again, now large enough to reach just outside the castle. "Do your best, and hurry!"
Neptune blocked out all stimuli and thought only about this dilemma and what ways she could solve it.
The Lambda Power made us incredibly powerful. Could that power be used to remedy this? I don't know enough about that power to say for certain. There was also that boost we just received upon merging our castles together. I'd much rather test this new power in a safe, controlled environment, but that would seem to be a luxury that's currently not an option!
She prayed that she would be able to help her lover and unleashed her new powers.
Suddenly, she was in several distant points in space at once, as well as still at the castle with Uranus. Before long, she could see Uranus' growing cock at every vantage point she somehow had. It was an unstoppable monstrosity now, growing lightyears in seconds.
She realized her current state was like an augmented form of her Deep Aqua Mirror's teleportation abilities. She wasn't merely perceiving several different points in space, she existed in each of them simultaneously. While that was potentially useful, she wanted to find the end of Uranus' impossibly large cock--give her beloved pleasure at the most sensitive part of her body, as well as enjoy it for herself.
Just like that, by putting her wish into words, she found the tip of Uranus' cock. Interestingly enough, it technically didn't exist. Her cock was constantly expanding and growing, to the point that its length became infinite, with its girth rapidly approaching same. It effectively transcended physicality.
The more she thought about how unbearably horny Uranus was getting, the hornier she herself became. She had never had someone cum inside her before--certainly not an infinite godcock--so she was excited at the prospect of experiencing it. It not existing in the corporeal realm may have complicated things for her before she was endowed with the Lambda Power, but not her now! She wasn't sure how to transcend the physical limits of reality, but wishing it so and applying her power seemed to do the trick.
The moment of penetration was like the first step into a bubbling hot tub: it filled her with a sudden rush of intense heat and excitement, which swiftly transformed into unfamiliar ecstasy, but certainly something she could more than get used to. Eager for more, Neptune started moving herself telekinetically up and down the godcock. Much to her delight, Uranus' godcock continued growing inside her, filling her more and more.
Having something that huge inside her and growing at alarming speed should have been agonizingly painful, but all the power within Neptune and behind Uranus' cock removed all pain and injury and replaced it with mind-shattering euphoria, which both parties were all too eager to add to by any means. Neptune sent her duplicates dotted throughout space to Uranus and her godcock to pleasure every bit of her and it. Duplicates created duplicates, and before long, Uranus had an infinite number of Neptunes pleasuring every point of her infinite body.
More than motivated to pick up the pace, Uranus thrusted faster and faster, harder and harder. She started absorbing the energy of distant stars, further increasing her near-unlimited source of power. Ecstasy permeated almost every bit of Neptune's being, to the extent she was close to losing her physical form entirely and becoming pure orgasmic energy. Noticing this, Uranus used her powers to keep her lover intact and corporeal. Neptune thanked Uranus for that by making the iteration of her actually being penetrated by Uranus' cock a thousand times tighter. Uranus responded in turn by siphoning entire galaxies for even more power.
Precum started flooding into Neptune. She felt her already absurd power double and redouble again and again. She wasn't sure if it was the precum causing this or the massive increase in pleasure. Frankly, she didn't care. All she wanted was more.
Uranus' body goes stiff as it finally reaches her first godgasm. An endless torrent of white rushed into Neptune so fast, so hard, and with no intention of ever stopping. So much power was behind her godgasm that it transcends space and time--in effect, both Uranus and Neptune have always been feeling the infinite, constantly rising pleasure of their godgasm. All the ecstasy the two had felt up to this point was almost like pain compared to it.
So much orgasmic power was unleashed wantonly from the two that the forces keeping the universe intact didn't stand a chance. The fabric of reality tore open before finally collapsing under the absolute power and lust of Sailors Uranus and Neptune.
Meanwhile, the other Guardians, scattered across the universe, were so powerful that they were barely even inconvenienced by the accidental end of the universe.
The two started tearing into adjacent universes for more power to feed on, to further increase their ecstasy. Before long, the multiverse was depleted, so they moved on to the next one.
Again. Again. Again.
The two continued fucking within the void. There was nothing left to fuel their growth anymore, yet they kept going, kept cumming, kept empowering each other with cum and pleasure.
There was no end, really, but that itself was the end. The two Guardians looked back on infinity, endlessness as a whole. Even now, they still fucked, continuously becoming more, but the lack of time progressing caused them to eventually become used to the infinite god-sensations and regain some semblance of lucidity. Constantly increasing pleasure, while undeniably fantastic, became the new norm, especially in a realm of literally nothing else.
"Oh my!" Neptune exclaimed, finally realizing what happened.
"That sure was fun," Uranus commented.
"Yes, but..." Neptune replied, "we destroyed, well... everything in the process."
Uranus looked around, noting a distinct lack of anything that wasn't herself or Neptune.
"Well, shit. Didn't mean to do that."
"I suppose, being literally the only things left, we have a responsibility to remake everything."
"And, since we got to this point through fucking, obviously the way to get back is more fucking!"
Neptune smiled. "You read my mind!"
With that, the two Guardians got underway even more rigorously than before. This time, however, they had the lucidity to be in control of their sexual energies. They used those energies to create anew every multiverse they had destroyed. They became the source of everything, intertwining themselves with existence itself--to the point that they put the Galaxy Cauldron to shame.
Their eternal fucking and ecstasy was like an engine that kept existence alive and thriving. The mysterious spark of life within sentient beings came to be the result of two omnipotent Sailor Guardians from an ancient universe making love beyond space and time.