Disclaimer: I don't own Sailor Moon or Marvel Avengers. They both belong to their respective owners. 

Distant Future

"Now. Go back to your home. To the place where you are suppose to be," Sailor Cosmos raises her staff and sends the Sailor Quartet back to their time period before she too heads back to the ruins she calls home.

Sailor Cosmos surveys the mass destruction before her and, in the midst of it all, stood Sailor Chaos.

"Sailor Cosmos," Sailor Chaos purrs as she calmly strolls to her arch nemesis as if they were old friends. "Where have you been? It has been quite lonely destroying the universe without you stopping me, almost takes the fun out of it... almost."

"Your reign ends here Chaos," Sailor Cosmos states, stern, her eyes shone with hope and determination, she gripped her staff tightly as she stared down the Senshi that eradicated her friends and family.

Sailor Chaos appears startled for a moment before she bursts out cackling which echoes into the nothingness of space, "After all these eons, you challenge me?! What happened to that little coward who fled and abandoned the place she swore to protect? What makes you think that you can defeat me?" Sailor Chaos taunts, fully enjoying the show.

Sailor Cosmos did not share her humour and sliced the air with her staff, posed for an attack, "I am Sailor Cosmos. As a Senshi it is my duty to keep on fighting even when the battle seems lost, even when my allies are deceased, even when all seems bleak, I will fight for a better future. Enough talk, fight me," Sailor Cosmos demands, prepared for a fight to a death. 

"How foolish," Sailor Chaos notes, a hint of annoyance underlined in her words, before getting in position, "fine. I was getting tired of keeping you alive, you've outlived your usefulness."

The two summoned their magic and engaged in a fierce battle between darkness and light. Both evenly matched one another, when one attacked the other defended. The two fought long and hard, the battle continued on for what felt like years, when in reality it was simply a few hours.

"Urgh!" Sailor Chaos growls, fed up with all the fighting. "Why won't you die?!" She shrieks, sending another blast of dark energy.

"Because I cannot give up!" Sailor Cosmos announces, remembering Sailor Moon's words, "as long as there is life in my breath, I shall fight for tomorrow." All of a sudden, a bright light exonerates from Sailor Cosmos's body; it was so bright, so warm so she prayed, 'To all the Senshi's whose crystals dissolved within the Cauldron... please lend me your strength.'

Sailor Cosmos prayers were heard and a blinding light pierced from Sailor Chaos's body who shrieked in agony. "What's happening?!" She exclaims in horror and bewilderment as more and more light exits from her body.

"It is the power of all the Senshi's you have slaughtered in your path," Sailor Cosmos informs, calmly, as she watched the demise of Chaos. "You have fused with the Cauldron so their Sailor Crystals live within you, they hear my voice because of this," a pure white light appeared in Sailor Cosmos hands, "this is the power I have received from Sailor Moon. The power to lose everything... the power to save everything... since I cannot vanquish you without dooming life itself, I shall use it to send you in deep slumber so that life will have the chance to prevail."

"Hehehe, can't kill me so you settle for the next best thing?" Sailor Chaos jeers as she slowly faded out, "doesn't matter, it just means my plans are on hold. I must admit that it will be quite annoying if you try to stop me again so best be prepared," Sailor Chaos sings as a dark spear plunges itself deep in Sailor Cosmos abdomen.

"Guh! Ugh!" Sailor Cosmos gasped and groaned as her sensory nerves exploded with pain. 

"You won't stop me, Cosmos. I'll be back, but you won't. Bye," Sailor Chaos promises as she enters her elongated slumber.

Sailor Cosmos holds her stomach which was gushing out blood, if she were a normal human, she would bleed out in seconds. Her skin slowly losing colour, making it an unhealthy hue. She heaved out huge breaths of air, attempting to calm herself while trying to heal her wound. Her attempts were fruitless as Sailor Chaos was the stronger one of the two. Black spots started to appear in her vision, her mind went hazy and just when she was about to embrace the darkness, a timid yet powerful voice calls out to her.

"Sailor Cosmos, can you hear my voice?" Sailor Cosmos opened her eyes at a crack, she peered through to see what she believed to be a fairy. The fairy, seeing that the Senshi would not last long quickly explains her appearance, "I am Guardian Cosmos, guardian of the Cosmos Crystal that resides within the Galaxy Cauldron."

"Why... are you... here?" Sailor Cosmos questions, her voice came out so feeble and her lips were quivering as she spoke.

"To save you," Guardian Cosmos replies before offering her dainty little hand, "it was the wish of Sailor Moon when she first defeated Chaos. She worried about what would happen to you so here I am."

"Ha... such benevolence..."

"I shall send you to a far away world for you to recuperate without worry," Guardian Cosmos informs as she uses her powers. Sailor Cosmos wounds were too much for her so she ends up fainting before she could inquire more, but that didn't matter as Guardian Cosmos teleports Sailor Cosmos across the galaxy. "Stay safe, Sailor Cosmos," Guardian Cosmos beseeched, quietly, as she watched Sailor Cosmos form grow smaller.

Little did both know, it wouldn't be Sailor Cosmos who landed on the other side.

Forest Outside Austrian Hydra Facility 

A little girl with red hair laid on the ground amongst the scattered leaves and dirt. Ever so slowly, her eyes fluttered open to see a full moon right above her head, she didn't know why, but it felt so soothing like looking an old friend. She languidly sits up before examining her surroundings, she didn't know this forest, she didn't know how she got there and, in fact, she didn't remember who she was.

Realising that she couldn't just sit there, she gets up and skips in one direction, remaining oblivious to the war happening around her and the danger she was in. 

This was originally going to be a one shot, but then the detail I added... damn you, brain! Let's see where this takes me.