Disclaimer: I don't own Re:Zero or anything from Fate/Nasuvere.

Prologue: The End and Start of a Life

The burning comet fell from the sky, hurtling toward the ground at an ever-increasing speed… although it was clear it would burn up long before making contact with the ground.

Where...am I? What was I...oh. I'm falling, aren't I? Ah... it hurts... I'm burning up... my body... my soul... it hurts... it really, really hurts... how did this happen? Oh, that's right... I was fighting.

Minutes Prior

All I ever wanted was to live a life filled with drive and purpose... I guess you could say I wanted... no I needed a reason to justify my continued living... any substantial reason would have been enough... but I always had a certain fondness for wanting to help others. I thought if I could live a life dedicated to something like that then maybe, just maybe I could be happy with the life I lived

I know, it's a silly idea, right? Especially for a magus like me... yet I thought I could show all of the others that their cruel selfish way of life was wrong, that we could all work together towards something better- better than the status quo we had maintained for far too long. I wanted to see a future like that... but, of course, that line of thinking led to isolation, betrayal, and all those sorts of tragedies. To be honest, I'm not sure why, despite all that, I still decided to keep chasing those silly ideals.

To think that following my bizarre goal would lead me here, to this outcome. Well, I don't regret it but still, I wonder if there could have been another way my life could have played out... but then, it's far too late to turn back now isn't it?

...

The magus let out several raspy breaths, struggling to regain control of their breathing. It seemed that they had lost consciousness for a brief moment after that last attack had hit them. Shaking their head, they reined in their leftover strength and started moving once more, forcing their body to stand, to get off the ground, their body screaming in protest all the while.

My body no longer has any strength to continue fighting… my legs are shaking. I can't even raise my arms... or well the one arm anyway. My magical energy is all tapped out... yet, despite that, I refuse to give in now!

Wounds, broken bones, bruises, cuts, and most concerning of all, a sizable hole that ran straight through their stomach- the newest and most deadly injury so far. It was clear at this point that without retreating and seeking treatment, death would be both imminent and inevitable for the beaten-down magus. Yet they forced themself to take a step forward, they wouldn't- couldn't back down here, not at this pivotal moment, they refused to disembark from the path they had chosen, so they turned their gaze upwards, towards the enemy, the invader from the stars. The power of the foreign being was building up, no doubt in preparation, the sheer quantity of mana emanating from them was enough to force anyone to their knees, yet the magus stood straight, ready to oppose the one who sought to end all of humanity.

The invader's next attack would bring an end to the world itself, it would be all-encompassing, a power that nothing on this world could ever hope to contest with- it was a conceptual force of destruction that once unleashed would bring a definitive end to the intended target without fail.

That's why! That's precisely why I can't afford to back down now! So please, holy sword... lend me your full strength, enough so that even this shattering soul of mine can make a difference, just this one last time. They look down at the place their right arm used to occupy... in its place was a decorated silver arm- Airgetlám. They tap into its power, causing it to flow with shining divine energy. This was the light of the planet, the light of humanity itself made manifest and weaponized. Instantly, pain shot throughout the mage's body, the stump the arm attached to literally burning in agony, and more than that... they felt their very soul continuing to break down- a pain worse than any other the mage had ever known. Strangely enough though, the wielder of the arm could only smile at the feeling, at that moment, they couldn't help but recall that one brave person who had helped them make it this far. That heroic spirit and knight of the Round Table- the friend they had come to treasure so dearly throughout the Holy Grail War, Bedivere.

So this is what it feels like to have my soul consumed, jeez what a horrible burden to carry. I'm amazed that you were able to wield such a terrifying power while you were alive, you were truly the most loyal of all knights Bedi... Still, I'm happy that it was you who answered my call instead of the King and I'm so grateful that you decided to save my life even at the cost of yours. Thank you for giving me this chance to keep fighting... I won't let it go to waste, even if I can only stand for just a few more moments.

That was the fatal flaw of the arm- if one lacked the proper amount of magical energy to wield its power- it would compensate by eating into the very soul of the wielder utilizing it as a sort of fuel for its activation. In life, Bedivere had faced the same burden and risked his very soul to complete a 1,500-year task... and in the end, before his soul was destroyed, he was recognized as a hero by the Counter Force. As a result, he ascended into a heroic spirit, which made the inevitable meeting between the two people possible, the knight from a bygone age and the magus in the current era- servant and master.

It was because of those very actions taken in the distant past, that right here and now humanity would have a chance to survive.

I... I'm not some grand hero, I never succeeded in becoming a user of true magic or anything fancy like that, and in the end, I'm just a failed prodigy of a mage who only made it this far because of my abnormal abilities. In the eyes of the world, I might as well be a nobody... but even so, despite it all, I still care for this world, for the precious memories it gave me... and now thanks to you I have a chance to make a difference, to save everyone. A chance to finally succeed. So thank you Bedivere, thank you brave knight of the Round Table for believing in me. I'll take this borrowed power and use it to bring this all to an end.

They stared up at the invader in the sky and forced themselves to move forward one last step. Now, finally, they were in position to act.

"Fall..." The magus called upon their mental trigger- channeling the last vestiges of their energy into action. Actualizing the power of their most treasured mystic code they felt themselves shoot upward into the sky, carried on rapidly fading wings of light- its white feathers burning away by the millisecond. The lack of magical energy meant that the mystic code could only work for a brief moment before giving out... but that was more than enough time. The ever-distant gap between heaven and earth was crossed in a matter of seconds. The magus spoke once more, calling forth the silver arm's power.

"Switch on Airgetlám."

Light started to pulsate from the arm and the searing pain in their broken body amplified tenfold… yet the magus simply grit their teeth and continued the activation chant.

"Devour my soul and come forth! O Silver Shooting Star- Dead End: Airgetlám!"

Light encompassed the arm as they swung it forward towards the foreign god and a blinding wave of golden light shot forth- filling the sky as it rushed out toward the enemy.

In response, the invader paused, having been just about to release their power of destruction upon the world... yet upon seeing the light they found themself stopping in a moment of hesitation having realized the true form and purpose of the arm. Its true name was —––——––— a weapon made to ensure the continuation of the human order- a weapon forged in the core of the planet. Due to this reason, the weapon shined most brilliantly whenever it was turned on those who sought to bring an end to humanity. It could against such a threat, pull energy from the world itself to ensure its power would be enough to take down the enemy of humanity. In other words, it existed to stop something exactly like this invader- one who sought to end the world of mankind.

Yet the recognition of that fact was not what had made the foreign god hesitate... no it was the lesser-known ability of the weapon that caused the god to stop. The very light of the weapon could invoke nostalgia in those who see its light- a precious memory, forgotten hopes, even their very dreams could be reflected by that glorious light. It was that vision that caused the invader to hesitate, to doubt their actions, and though it was only for a single moment- that was more than enough time to ensure their downfall. In the face of such overwhelming power, the invader could only smile, and allow the warm light of the planet to wash over them.

As for what happened to the one who defied the god? Their soul could not handle the strain of unleashing Airgetlám's true power. They fell from the sky in an uncontrollable freefall, their body starting to crumble apart into ash.

Present

Ah right. That's how I got here, I managed to win... and now I'm fading away. My soul is burning away. Ah, it hurts... damn it... I'm starting to forget... what was my name again? I can't remember. But... even so... this was the best result right...? I saved everyone, so it's okay for me to die now right?

No... no I can't! I can't die yet! I refuse- I've spent so long fighting, trying to make a place where I could... where I... where... huh? Why can't I remember what it was that I trying to do? Who was I again? My name was... —––—, Oh, I can't remember it anymore, it's all disappearing now... fading away.

This was the only outcome that could occur for the mage. By this point in the fall their soul had already mostly fallen apart, their mind in shambles. Blurred memories rushed past, faces, places, and precious moments alike, all slipping away, disappearing bit by bit.

There's nothing I can do now is there? Though... at least I managed to save everyone... surely that must count for something.

The now nameless one could only smile at their own helplessness as the ground rushed to meet them. Moments later, before they could crash into the ground, their body dissipated, turning to ash.

Still, If I could... if a broken soul like mine could ever be allowed to continue living... I would like to live a life full of meaning- more than just working toward some obscure goal or even more than dying for the sake of saving others... I would like to see if someone like me could ever find something genuine for myself... a place where I truly belong. Heh what a silly wonderful life that would be.

Root Status Update

—––—'s soul has been mostly destroyed... note of interest- the soul remnants have fused with —––—––—- recalling it to Root to be recycled... error... error. Otherworldly interference has been detected. Foreign Invader detected, preparing countermeasures... complete failure, preparing second stage countermeasures.

Error... can no longer read the status of the soul remnants of —––— nor detect the location of Foreign Inavder…

Stand down second stage countermeasures. Record the loss of —––— for record-keeping.

…

Location: Unknown

"Where... am I? Who am I... no even before that... who or what are you?" Asks the shattered soul to the being floating before them. A pale woman with long silver hair floated before them in the void, she was engulfed in shadows, and a veil covered her face. Somehow... they seemed sad or at least that's the impression the magus got from observing them, they seemed to be in grief over something... or perhaps, grief over someone?

"Please... help me save him... help me save my beloved one."

"I... you want me to save someone? I-I'm broken... burned and without a body. I'm pretty sure the only reason we're able to talk right now is due to your power holding me together. I don't even remember who I... I'm sorry, there's no way I can help you like this."

"I can help you, I can piece you back together... so please, he's suffering all alone... no one will be able to understand him, his burden will be far too much for him alone, he will lose himself, and then no longer care for himself. You can stay by his side, be there for him, and you can live again- pursue your wish, so please accept my offer... please help him."

"That so... jeez this person sounds like they could end up pretty roughed up. Strangely I get the feeling I knew someone like that once. Also, pursuing my wish? Huh, I wonder what it was that I... ah right I lost that memory, how troublesome, oh well. Mhmmm, you know what? Let's do it, I don't mind helping out, and if I can remember what it was that I had wanted to do then and accomplish it this time then... that's all the better. By the way, I uh assume by 'piece back together,' that you mean you can restore my memories, body... and even my soul?'"

The woman reached out toward the broken soul with a gentle demeanor and a sorrowful, yet slightly hopeful smile.

"Thank you... thank you so much, I will do what I can for your current state. I hope you find what you're looking for alongside my Subaru…"

Moments later, the two disappeared, leaving behind an empty void between worlds.

AN: Welp here we go again, my second attempt at doing a Re:Zero/Fate crossover… I did write out a few more chapters of the first story but life kind of got in the way and I had to stop writing for quite some time. I can't say my situation is much better than before, but I wanted to give writing another chance and decided to start fresh… so here we are! In my last story, we had Bedivere crossing over while this has an OC being chosen this time around- and while they do have Airgetlám like Bedi did… well they are a magus so expect big differences. Also, I don't care much for being super accurate to the overall lore or the mechanics of magecraft established in the Nasuvere… so expect me to take some huge liberties on that end for the sake of telling the story I have in mind. Ah, and the briefly mentioned mystic code used in this chapter is inspired by the wings used by Circe in Fate/Grand Order (and by the valkyries for that matter) but I'll expand on all that later.

Oh, and in case you were wondering this character was based on a loose story idea I came up with a while back regarding a magus who summoned Bedivere in a Holy Grail War. I'm not going to say much about it in this story though beyond the OC making references back to it for the sake of context for their character/backstory bits. So if this chapter's context was hard to grasp- well it doesn't particularly need to be understood for the story beyond serving as a bridging point for getting my OC Isekaied over.