Figured I would join in on some Peggy Sue fix-fic action while waiting on updates of other fics. Hope you enjoy!

Warning: Spoilers for all routes ahead.

Chapter 1: Memento Mori

"Eyes in front, prisoner."

Byleth sighed deeply as the two Knights of Seiros flanking him on either side harshly grabbed hold of his arms, a third keeping his sword placed level under his chin. Any false move, any attempt at a final rush for freedom, and he'd be dead before he knew it.

So they said, anyway. Byleth knew better. Death from a puncture wound anywhere in the neck often came slowly. Without severance of the spinal column, exsanguination or asphyxiation were excruciating ways to die.

He allowed his hands to be bound tightly behind him. Then, for good measure, his feet were bound as well, despite him already being handily restrained by knights on either side. When that was done, he was patted down once more and subjected to a search of his oral cavity, despite that process already having been carried out several times. Only then was the gate to his cell opened, and he felt himself being hoisted into the air by hands gripping tightly onto his shoulders.

"I hope you're ready for the Goddess' punishment, monster. Those were some of my friends you killed," one knight spat vehemently.

Trust me, I am.

Bound as his feet were, he couldn't keep in step with the full contingent of Knights and Priests of Seiros, stumbling several times as they marched through the dark hallways of Garreg Mach Monastery. Sights he'd seen many times over, sights he would see again.

He didn't even flinch as shadowed corridors turned into brightly lit ones. He barely needed a second to adjust to the sudden, drastic change in light. Any hesitation of that sort he once might have experienced had long since been rid from him.

An Assassin could hardly function if such petty things as day or night managed to hinder him, after all.

All along the path, a massive crowd larger than any he'd seen in the monastery before had gathered to witness what was to come this day. Knights kept them a good distance away, not trusting that any one of them wouldn't make an attempt to free him. Perhaps they were afraid that he could still somehow make his way to freedom by blending in with the crowd. Doubtful; even he had his limits, bound by thick cords as he was.

"Monster!"

"Demon!"

"May the Goddess punish your wicked sins!"

He took their heckling stoically. This really wasn't anything new.

There were some among the crowd that he recognised. How could he not? He could pick out his former students easily. One had to learn how to do that amid the chaos of a battlefield, after all.

Ignatz and Raphael looked uncertain and hesitant, mixed together with some semblance of disbelief. Hadn't they already had more than half a month to get over those emotions? Leonie glared at him fiercely, as though fighting the urge to run him through with her lance. By her side stood his own father, looking vulnerable and helpless for the first time. An unspoken question was clear on his face.

Why?

I'm sorry, he tried his best to convey, his movements restrained as they were. Jeralt was someone dear to him, someone he'd shed tears for, despite all that he had endured over the past years.

The procession moved uncaring of the wishes of the crowd. Soon, the rough stone beneath his feet gave way to damp grass, and then to the fine ceramic of the monastery's large courtyard. He was ushered onto a platform, weapons trained on him all the while, before yet more knights came to further limit his movements. There was almost definitely no means of escape now, unless Sothis saw fit to provide divine providence wherever she was.

He eyed the crowd once more. Rhea sat at the very front of the assembly, her face giving no clues as to what she was thinking or feeling. She was usually more impassioned at times like these, but he supposed that one didn't live more than a thousand years without being able to steel her emotions at will. By her side was Seteth. Unlike the archbishop, there was no mistaking the anger conveyed by his facial expressions.

The leaders of all three houses were in attendance just behind. Lady Edelgard, not yet an emperor, with Hubert by her side as she looked calculatingly at Byleth. Very much like her to be pragmatic at a time like this. She was probably thinking about how she would need to adapt her future plans.

Dimitri sat alongside Dedue, the prince making his hostility plain on his face. It wasn't the crazed desire for vengeance he'd seen at times of bloodlust on the battlefield; no, this was more the righteous anger on behalf of the lives that Byleth had taken. It was more in line with the beloved prince of Faerghus than the vengeful king haunted by past ghosts that he would become.

Claude sat as a representative of the Leicester Alliance, a smattering of Alliance lords gathered just behind him. Byleth recognised Count Glouster and Lady Judith of Daphnel from his past dealings with them. Unlike those from the Adrestian Empire and the Holy Kingdom of Faerghus, the emotions of the Alliance leaders were more muted, likely because his actions hadn't been directly targeting them.

The nobles among his students were present within their respective factions by the side of the leaders of their Houses. It was almost funny. The descendants of all of the Ten Elites gathered together in Garreg Mach, their collective animosity directed solely toward him. The idea of a meeting between all these great Houses that didn't involve a massacre of any sort was mind-boggling.

Compared to the fires of war that had ravaged the monastery many times before, this was very much a welcome sight.

Rhea raised a single hand as she stood, and as one the crowd fell into a reverent silence. He saw Edelgard's eyes narrow just fractionally, something that anyone could have missed had they not known her disdain for the church and the established order as he did.

"Byleth Eisner," she began. "Son of Jeralt Eisner, recently returned to the Knights of Seiros. I trust that you know why we have been gathered today?"

No sense waiting things out. "I –" his voice cracked slightly from disuse. When was the last time he'd even talked?

"I do."

Rhea nodded regally. "We are gathered here, on this fifteenth day of the Blue Sea Moon in the Imperial Year 1180 to pass judgment for crimes committed against the Adrestian Empire, the Holy Kingdom of Faerghus, and the Church of Seiros."

Had it only been four months? He worked faster than he had expected. Still, that was a remarkably short time he'd lived.

She gave some time for the shouts to settle before continuing. "You have been charged with the murders of Lord Volkhard von Arundel and Count Bergliez of the Adrestian Empire. Do you deny these claims?"

Byleth didn't know exactly who Arundel was in his true identity, but there were enough clues pointing toward him being one of those of the ancient Agarthan civilisation in Shambhala, perhaps even their leader. Hubert had coined the term 'Those Who Slither in the Dark' when referring to them, but that was too much of a mouthful for Byleth's tastes. Bergliez had been targeted for his future contribution to the war in his position as Minister for Military Affairs.

"I do not."

"You have been charged with the murder of the mage Cornelia in service to the royal family of the Holy Kingdom of Faerghus. Do you deny this claim?"

Cornelia's involvement always tore the Kingdom apart in her coup. It didn't matter whether or not she chose to side with or against the Empire; the fractured Kingdom couldn't withstand an internal struggle alongside Empire incursions. She had to go.

Besides, killing her was always something he hadn't been necessarily bothered about, after all that she had done – would do – (would have done?) to Dimitri and the Kingdom. Her association with the Agarthans further sealed the deal.

"I do not."

"You have been charged with the murders of the librarian Tomas and the instructor Jeritza in the employ of the Church of Seiros. Do you deny these claims?"

He was even less conflicted about those, knowing with certainty that they were both aligned with those of Shambhala. Solon and the Death Knight had been responsible for the deaths of many of his students and his father. He'd tried reasoning with the Death Knight, once, out of respect for Mercedes. He didn't bother attempting that again in all his lives since. That death was one he wouldn't forget quickly.

For the lives they'd taken many times over, killing them had almost been a pleasure. A knife in the back when their attention was divided, and then ten more for good measure. He wasn't foolish enough to attempt fighting them face-to-face; for all that Byleth was skilled, the Death Knight still usually managed to put up a reasonable fight in a fair battle. In any other scenario, someone of his age would have been hailed as a prodigy.

"I do not."

"Let it be known that the prisoner Byleth Eisner has pled guilty for all his crimes," Rhea declared. "For the assassinations of the foremost eminent lords of Fódlan and respected members of the Church of Seiros, you are hereby sentenced to death."

No surprise, really. Even if that hadn't been clear to him over the past few weeks of confinement, the executioner holding the giant axe by his side was a dead giveaway to this sham trial.

They didn't really need to hold one, given that he'd carelessly been caught by Ingrid right after his assassination of Jeritza, his blade and tunic still bloodied. Skilled though he may be in most manners of combat, even he couldn't singlehandedly take on an entire troop of knights led by Catherine, Gilbert, Alois and Shamir.

He could have escaped, of course, but that would require silencing his dear student. Even after all these years, he still hesitated to kill one of his students outside of a battlefield, and even then, capture or forcing a retreat or surrender were preferable options. He knew just how much dying hurt.

There were shouts of approval from those assembled, cries for the Goddess' divine punishment. He saw his father looking stunned, a few tears visibly streaking from his eyes even from where he was on the executioner's block. It mirrored the events from lifetimes ago, the first time that Byleth had ever seen his father die, murdered by the true enemies lurking beneath Fódlan.

"Do you have any last words?"

What could he say? How could he possibly explain Arundel's involvement within the secret organisation that had existed for millennia in Shambhala? How could anyone believe the grandiose tale of their true capabilities, of javelins of light capable of destroying even the most fortified of cities? Why would anyone believe him if he spoke of Edelgard's goals, of the inevitable war to come? Of Cornelia and the coup that he had prevented?

They never believed him in the past, and they never will. He had stopped trying seriously a long time ago.

Rhea had believed him to be one of the Agarthans, even when he brought up facts and secrets that only someone she had personally disclosed them to could know. The Agarthans had been around for a long time, and were the ones originally responsible for the twisted use of Crest Stones, after all. For all her strengths, Rhea had always been somewhat paranoid, quick to anger and overly reliant on a show of force to settle any dispute. Likewise, Dimitri had brushed aside his concerns regarding Edelgard, and Claude had retained Alliance neutrality.

It was not until Fódlan became ravaged by war that anyone would come to realise the truth of his words, but by then it had always been too late. Everyone lost, in the end.

With the cursed existence that had been placed onto him under the guise of a gifted power from the Goddess, he'd never been able to directly influence the early days of the war. Like many other things, the five year gap was an absolute fact of each lifetime he'd experienced, even if he chose not to take part in any of the business that crippled Fódlan.

That one time he tried to break away from it all, to live a simple life in a remote village, he'd simply fallen asleep one day and woken up the next just before the Millennium Festival years later. War came to his village soon after, and he fell fighting both Empire and Kingdom forces. Moments later, he was back where it all started.

It was a mystery as to why that was an inviolable fact amid all the other shifting variables between his lives. Something must have had gone wrong during their merger, because the Divine Pulse had never worked as it did before, all those years ago. All of established Reason and Faith theory had no explanation for such phenomena, despite him probably being in the same league as top scholars of the field. He had plenty of time to hone his skills.

He hoped that this time, with the key players of the Agarthan faction crippled and Bergliez unable to take charge of the Empire military, Edelgard wouldn't have the military force she needed to launch her assault on Garreg Mach. Without Cornelia in the picture, when the war did come, the Kingdom should be better prepared to stop it.

With the scales of the balance of power between the two major military forces of the conflict favouring neither side, that would hopefully be sufficient to reduce the impact to Fódlan and minimise casualties. He had no doubt that some Agarthans remained in Shambhala, but with their leaders taken out they should be more reserved in the use of their full destructive capabilities. Perhaps Sothis would see fit to let him rest at long last.

Then again, he had no idea exactly what Sothis wanted, why he had been cursed to relive the certainty of these events no matter what he tried. Ever since his first pass at life, her voice had turned silent. Was the reason for her gifted power's unsolicited activation in order to preserve the lives of his students, to prevent the war from starting, to bring about peace to Fódlan or some other purpose entirely?

Rhea accepted his silence as an answer. He looked at her directly in the eyes as she gave the order.

"Do it."

The swinging of an axe, a brief spike of pain that quickly turned numb – a merciful death, better than many he'd experienced – and then…

…nothingness.

Just as it had been.

Just as it always will be.

Slowly, the dark veil gave way to vibrant colours, a sight that he'd seen many times over. So, this attempt hadn't worked either, then.

He would have sighed, but he didn't have a mouth at present. Nor did he have the energy for it, really.

All the lives he'd lived, and nothing to show for it. The war always happened, one faction would win, but ultimately the Agarthans always emerged the final victors. Whether it was through their weapons of light or the army of a revived King of Liberation, it didn't matter. In the occasions where Byleth lived to see it through to the end, all of Fódlan would lose. It was a circle without beginning and end – Byleth would die, and Byleth would live again.

The first few times had been exciting, novel. After his first life spent teaching the Golden Deer house, he had made countless attempts rotating between all the other major powers. He had come up with plan after plan, distinct variations that dramatically changed the outcome of the war. He had experienced entire lifetimes spent fighting alongside the Empire, the Kingdom, the Alliance and the Church, and then several more where he'd struck off independently.

The only faction he hadn't worked with was the Agarthans, if only because they would probably desire nothing more than to study the Crest Stone and whatever other mysterious power Sothis had gifted him. It was a pity; information from working with them would be priceless. As it was, after the many repeats he'd gone through, each subsequent life barely gave him any new information.

Yet, there was still so much unknown to him, so many secrets held close to the hearts of all the major players, muddled by misinformation perpetuated by each faction. Edelgard and Rhea had presented vastly different accounts of Crests, the Goddess, the Church and Nemesis. The truth behind the Tragedy of Duscur was still unclear despite hearing the accounts of Edelgard, Dimitri, and even some of the Agarthans. Each party held on to their own set of beliefs, refusing to address their own biases and possibility of false information.

His enthusiasm quickly gave way to apathy after tens to hundreds of attempts he had long since lost count of, as he was forced to see the students that he had taught at one point or another raise arms against one another again, and again, and again. There was only so much one could take before realising the reality of his situation. He was trapped, cursed to see Fódlan descend into chaos over and over.

Nowadays, he tended to come up with ideas on the fly, living day by day against the certainty of that which was to come. This time around had been an outlier, an experiment in influencing the political field early on by assassination and subterfuge. It seemed that it wasn't what Sothis was looking for, given that he would soon find himself back at Remire Village.

The colours shifted into familiar scenes. The Tailtean Plains, Saint Seiros slaying Nemesis. The same plains, more than a thousand years later, as Emperor Edelgard von Hresvelg slew King Dimitri Blaiddyd in single combat. In another life, the situation had been reversed, a vengeful king gleefully laughing at the fallen body of his foe as his lance jabbed into her again and again, ignoring the storm of arrows raining down upon him.

Rhea's voice from his first lifetime, and then many more after that, singing that damned song that had haunted him all these years.

In time's flow,
see the glow,
of flames ever burning bright…

The Monastery in ruins. Arianrhod and Fort Merceus, left as nothing but craters in the ground as spears of light struck them. Fhirdiad, Enbarr and Derdriu in flames in different lifetimes, the cries of civilians lost amidst the chaos of war. Ashes scattered amidst dying embers in the aftermath of a cruel war. Two armies bearing the Crest of Flames meeting in battle in a small number of lives, one always emerging the victor.

On the swift
river's drift,
broken memories alight…

The broken, bloodied bodies of his students. Ferdinand, brought down by arrows and magic where he stood unwavering from the Great Bridge of Myrddin. Ashe, his body smaller in death than he'd been in life, as he lay unmoving on the boiling stones of Ailell. Marianne, slain by one of Edelgard's knights as she tried to evacuate civilians from Derdriu during the Empire's assault.

Metal and stone collapsing all around him as the massive underground city of Shambhala was brought down by the Agarthan leader's final act of defiance. The Empire, Kingdom and Alliance forces looking skyward in the Gronder Fields where a parley had been called, as javelins of light rained down from the heavens onto all three armies in that one lifetime where a true possibility of peace had been just within their grasp. War-torn worlds flying banners of Adrestian black, Faerghus blue or Leicester yellow, unable to withstand Nemesis' return in the wake of a war that had crippled all of Fódlan.

More images and memories flashed by, some he lived through and some he hadn't.

The final remains of a goddess stolen.

The Red Canyon massacre.

The scorching of Ailell.

A Saint's act of sacrilege.

A dimension of darkness.

An empty throne.

And then –

- a room he'd seen tens, hundreds, perhaps thousands of times before. The sound of hurried footsteps as Jeralt made his way up the stairs, the creaking of a door a moment later.

He got up to his feet, catching a brief look of himself in the mirror as he turned his head. His body was smaller and scrawnier than it had been nary minutes ago, a constant in all the lives he lived. He may have had past experiences as a War Master, Dark Knight, Wyvern Lord or just about every defined Class that had categorically existed, but skill was pointless without the power to back it up. As always, he would need to train.

Then again, overwhelming power was never the answer. That one desperate life where he'd trained till his mind and body had figuratively been broken, he'd still fallen against the Death Knight, Solon, Kronya and their enigmatic leader when the time came. It took several lifetimes to recover from the ordeal he had put himself up to.

His hair was the dark blue it had always been. The mint green that so mimicked Rhea and the other Children of the Goddess had been present for only his first lifetime, disappearing upon his first death, another mystery that he had no answers for.

"Hey, time to wake -" his father paused mid-sentence. "Oh. You're already awake."

He stretched lightly as he got used to his past body once again. Thankfully, with his last life only lasting four months, the differences weren't particularly jarring. Small mercies.

Here we go again.