Summary: Sometimes, things don't work out in the end. Hyōdō Mordred learned that personally. Watching as his loved ones and the world around him fell to ruin, he decides to take matters into his own hands. After all, what is a magician but one who rewrites reality? But to save those he cares about, his only choice is to travel back to where it all began and try not to kill his teenage father along the way.

Pairing: Mordred/Kuroka/Lavinia

Warnings: This story will contain explicit content of an adult nature. It is High School DxD, so this should be expected. This story will also contain time travel, though I'd hope that would've been obvious already.

Disclaimer: I do not own High School DxD.

Chapter One

Hyōdō Mordred stepped gingerly beneath the broken pillar, careful not to even breathe on it. His movements were smooth yet cautious. It had been ages since this place had come to ruin, unlike the rest of the world.

As unfortunate as it was, he could not risk actually using his magic in any serious way as he navigated the ruined Persian castle. The last thing he needed was to attract the Endless to this place before he secured his prize.

It was only when he reached the altar that he allowed himself to feel hope. It was flush against the stone wall with a high back that reached the ceiling and had three large dragon heads extending from it. To most, it would have appeared to be a dead end, but it was exactly what he had been searching for.

Taking a deep breath, he approached the altar and found a rune-engraved tablet just below the dragon heads. Dust coated every inch of the tablet, but the thirteen runes were easy to see. Tracing each rune in the proper sequence, the altar began to rumble. Even the slightest error in the patter would have resulted in a fate worse than death.

Slowly, the altar sunk into the floor. It was fortunate that the ambient magic of the ruins was capable of masking small spells. Without that, teleporting to the ruins and activating the Evil Dragon's altar would have spelled doom for him. A hidden doorway sat behind where the altar had been moments earlier. Passing through it, there was yet another altar, but this one was different.

Unlike the large altar that had been placed to hide this room, the new one was small- only a few feet tall with a mere square foot of space atop it. Like the previous one, it was decorated with imagery of a three headed dragon with six wings, but it was not the altar that he sought. Rather, it was what lay atop the altar.

Reaching for it, he grasped the ancient grimoire, pushing down the revulsion that threatened to overwhelm him as his fingers brushed against the cover. Human skin had a rather distinctive feel to it.

A moment later, a dark curse flowed from the grimoire, but it could not find purchase. The empty scabbard at his hip began to glow at once, its holy aura repelling the dark influence. Even so, the curse still remained within the tome until he lifted it from the altar, at which point it faded completely. According to Mordred's research, all who had tried to recover the grimoire had fallen to the curse. But unlike him, they did not have access to the scabbard of the legendary Excalibur.

"You are truly a piece of work," he muttered grimly as he wrapped the grimoire of Aži Dahāka in a sheet of red cloth and put it away.

Once the tome of forbidden magic was secured, a magic circle formed beneath his feet. Without even a second's hesitation, Modred teleported back to his quarters..

A sigh escaped the magician's lips when he realized that he was not alone.

Standing before him with crossed arms was one of his older sisters, Helmwige. With her stern blue eyes, long silver hair in a single braid, and crimson Valkyrie armor, there was no mistaking her for anyone else.

"Really? Sneaking out again. I seem to recall telling you the next time, I would let Airi know." Helmwige glared at him fiercely.

Mordred just sighed. "Really? Threatening me with our big sister isn't going to make me less rebellious." His mother had always said that he inherited more than just the name of his ancestor, after all. "If you really want to tell her, go right ahead. Do you really think I'd have Zen's scabbard if Airi didn't know?"

Helmwige actually hesitated at that, her gaze lingering on the scabbard in question. "Airi wouldn't let you leave. None of us are supposed to leave Headquarters without permission from Mother Rias."

To that, he just snorted. "Helmwige, I'm not a soldier, and Rias is not my boss. I'm not exactly the obedient kind. But if it means that much to you, I promise I will be a good little boy and stay in my room."

With a huff, Helmwige spun on her heel and left. A twinge of remorse filled him as she departed. Of his ten siblings, she had always been the one he was closest to, but ever since her mother's death, her overprotectiveness had started more arguments between them than they ever had before.

A few minutes later, his eldest sister walked through the door. Looking so much like his favorite step mother, it was easy to forget just how dangerous Airi was. Among all of the Red Dragon Emperor's children, her strength was unparalleled. Only Ex came close to matching her.

"Mordred," the daughter of Asia Argento greeted with a conspiratory smile. "I trust you haven't been up to anything too exciting tonight."

"Not at all," Mordred said as he removed Excalibur's scabbard from his hip and handed it to her. "Thanks sis. I doubt Zen would've let me borrow that without your assistance."

Airi's smile faded for just a moment before it returned full force. "Just be careful, Mordred. I'd hate to see anything happen to you."

A warmth spread in his chest at that. Ever since his mother's death, it was not the most common sensation. "I'll try, but fixing things isn't going to be safe."

Airi turned away from him at that. "I know. But I've already lost too much. I couldn't bear to lose you too."

Mordred looked down at that. His mother, Le Fay Pendragon, had certainly not been the only one that the family had lost recently. Six of his step-mothers- Ingvild Leviathan, Elmenhilde Karnstein, Xenovia Quarta, Shidō Irina, Shirone, and Rossweisse- had all fallen in recent years. And for all he knew, his father might be dead too. It had been three years since he had even seen the man.

Shaking his head, Mordred shut the door and locked it before removing the grimoire of Aži Dahāka. Of the evil dragon's grimoires, this one alone was said to contain the forbidden spells related to space and time.

With this, he could fix everything.

For six months, Mordred had made no effort to leave Headquarters, as much as he hated the place. As the last refuge of mankind and the various mythologies of Earth, it always felt crowded and loud. Helmwige and Airi seemed pleased with his decision not to leave, but they had no idea it was all in the pursuit of forbidden magic.

Learning everything within the grimoire was beyond the scope of his abilities. There were a few spells in the tome that he had studied, but many of them were so vile that he never wanted to use them. In fact, there was only one spell that he truly wish to use.

At some point in the past, Ajuka Beelzebub came up with a formula that made time travel theoretically possible, but that method of time travel was susceptible to paradoxes. Anyone who used that formula could never have changed the timeline without erasing themselves from existence, becoming trapped in an endless temporal loop, or becoming entangled in one of countless other horrific scenarios.

Aži Dahāka's formula for time travel was different. It was a forbidden spell because it broke the laws of time travel. The spell was capable of removing its caster from the timeline and inserting them within a new one. Of all the beings to study time magic, only that dragon had discovered the calculations necessary to prevent paradoxes. Considering Aži Dahāka's role in what happened to the world, using one of his spells to fix everything seemed fitting.

When the appointed day came, Mordred traveled to the area beneath Headquarters. Back when the place was still known as Kuō Town, the place doubled as an emergency shelter and a train station to the Underworld. Now, it was mostly used for training and storing supplies.

In a barren room in the depths of the underground, Mordred carefully drew a magic circle with a mixture of ink and blood. The circle itself was the most complex of any he had ever used- truly a creation of the evil dragon whose skill with magic exceeded imagination.

Once finished, Mordred stood at the center of the circle and closed his eyes.

As much as he wished otherwise, he had not said his farewells to any of his brothers and sisters. It was easier this way, he supposed. Still, it did not make things any easier. To even imagine a world with Airi, Helmwige, or Kurenai, his favorite brother, was painful beyond measure. Even so, what he did now was necessary, even if it prevented his siblings from ever existing.

"Forgive me for being such a poor brother." The magic circle beneath him thrummed with power as he activated it. The faces of his four brothers and six sisters flashed before his eyes. To think he would never get to see any of the again, even Ex and Robertina, filled him with sorrow. "But sometimes, the world comes first."

A moment later, all sense of reality faded. The ground seemed to give way, yet there was no sensation of falling. Opening his eyes, Mordred found that his sense of smell, hearing, and even sight could register nothing. And then unconsciousness took him.

There was something about research and experimentation that Azazel always found liberating. Only within his workshop- a place as impregnable as could be found in all of the Underworld- could he truly be fulfilled. With what appeared to be a spear-shaped dagger in his hands and classical music playing in the background, Azazel could only grin.

The Downfall Dragon Spear Prototype Mark Seventeen had finally reached its completion. Would it work as intended? Personally, Azazel was doubtful of that, but there was no such thing as failure to a true researcher, so long as he learned something from the experience.

His elation came to a halt when his phone began to ring. Setting the Artificial Sacred Gear down and turning off the music, he answered the phone. "Azazel speaking."

"I have business with you, Governor-General of the Grigori. I'll be waiting for you in the underground of Kuō. Consider this a matter of life and death."

Without waiting for a response from Azazel, the individual on the other end- a young man if the voice was any indication- hung up.

Normally, Azazel would have wrote the call off as a prank or a trap, but his phone number was not something that just anyone could get. It was a private line, known to no one but the other leaders of the Grigori. Furthermore, he had already changed it since Satanael's betrayal to the Grigori.

"Hmm, he didn't actually tell me to come alone," Azazel noted as he pocketed his Artificial Sacred Gear and rose to his feet. "Perhaps Slash Dog should come with me."

He would have summoned Vali to come with him, but it really didn't seem like a good idea. Vali was too headstrong and his love for fighting was too strong.

Azazel and Ikuse Tobio arrived in Kuō a short while later, the brown haired Longinus wielder moving silently and alert.

It was certainly risky, passing through the territory of Sirzechs Lucifer's sister, but Azazel was unconcerned. Sensing the locations of the devils of Kuō while masking his own presence was a rather simple matter.

"Perhaps I should visit that boy Raynare's keeping an eye on," Azazel mused as the entered Kuō's secret underground. "If he really is the Red Dragon Emperor, it may make for an interesting meeting."

Tobio looked troubled by that tidbit of information. "Are you sure it's wise to trust her to keep an eye on a possible Longinus user? She never struck me as the most stable of your subordinates."

"I didn't tell her that's what I thought he had," Azazel laughed, waving Tobio off. "I just asked her to determine if his Sacred Gear has been awakened. I'm sure she wouldn't be stupid enough to kill a Sacred Gear possessor without orders." Given his obsession with Sacred Gears, none of his underlings would expect to be rewarded for killing possessors off unnecessarily.

The two walked in silence after that until they found they found a young man with short blond hair and blue eyes, wearing a white three-piece suit with blue accents. His face looked unnaturally pale and his breathing was labored, though it appeared he was trying not to let it show.

"Governor-General, I see you brought Slash Dog with you," the man said as he approached them. "I'd ask that you send your guard out of the room, but if it's that guy, I trust he can keep his mouth shut."

Azazel chuckled at that. "Yeah, Slash Dog is pretty good at keeping secrets, I'd say."

"Then I guess there's no beating around the bush. I am Hyōdō Mordred, youngest son of the current Red Dragon Emperor, Hyōdō Issei. I am from approximately thirty years into the future."

Azazel took those words in stride, not nearly as surprised as he perhaps should have been. Time travel was not such an impossible feat, after all. It wouldn't be strange if in thirty years, one of the Three Biblical Factions or one of the many magician associations devised a method for traveling through time.

Personally, he had long ago resolved never to set a foot into such a field out of fear of perverting history.

Slash Dog, on the other hand, was unable to maintain the same level of composure. "Time travel? Seriously? I've heard of some crazy stuff, but…."

"It's not the craziest thing I've seen or heard," Azazel assured him. Over the thousands of years he had been alive, the fallen angel had witnessed more than he fair share of insanity. "But that does beg the question of what you're doing here, Mordred. Somehow, I don't think you traveled back in time and asked me to come here just for an experiment."

"Not an experiment," Mordred said, flinching a bit as he walked. "I'm here because I need to change the future. In less than one year from now, Rizevim Lucifer will set into motion the release of Trihexa."

"Well, shit," Azazel muttered. Compared to that, time travel really wasn't all that noteworthy at all.

Rizevim Lucifer was certainly a pain in the ass back in the day. The son of the original Lucifer and Lilith had been the first transcendent-class devil in history, a so-called Super Devil. With his unique ability to cancel Sacred Gears, the man was dangerous. It was only his lack of ambition that kept him as a footnote in history.

But Trihexa was another matter altogether. There was a reason the Three Biblical Factions insisted that Trihexa did not even exist. The Beast of Revelations was an existence whose only equals were the Dragon God of Infinity and True Dragon of Dreams. It had taken the full might of Azazel's Father to seal away Trihexa, and such an effort had left him permanently weakened, resulting in his death during the Great War.

Slash Dog did not know anything about Trihexa, but Azazel could tell from a glance that the young man understood what it was just from the name.

"Trihexa was not free for long before you and the leaders of essentially every other faction decided to imprison it and seal it away in another dimension with all of you inside, but that was a temporary measure only," Mordred continued. "In the end, it only worked for twenty years before it escaped once again. In my time, there has been more death than you can imagine. Among all species and factions, we number no more than five thousand, and it's just a matter of time before that number dwindles to zero."

Azazel closed his eyes. Just picturing such a situation was horrifying. "And you think you can change the future? I'm pretty sure the first law of time travel is that you can't change the future without causing a paradox. If the future doesn't happen the way it did for you, then you would have had no reason to come back to the past."

In answer, Mordred showed him an old book, and everything clicked into place.

"No wonder you don't look well. Aži Dahāka's grimoires are filled with spells that should never be used." Only a truly desperate man would have ever considered using forbidden spells of that caliber.

Mordred laughed quietly at that. "I'll recover in time. But as you can see, I'm not bound by the conventional rules of time travel. Still, I'm going to need some help if I'm going to prevent the fate that befell my world. Will you help me, Azazel?"

"Of course. Just tell me what you need."

After the pair left, it took all of Mordred's willpower not to collapse to the ground. From the beginning, he knew that Aži Dahāka's forbidden spells were forbidden for a reason. He was merely an ultimate-class magician, not a transcendent-class one like Aži Dahāka, so the backlash of the time travel spell was far more intense than it should have been.

It had been risky, meeting with Azazel in his condition. If the fallen angel had decided that he was a threat, he could have easily captured him without putting forth any semblance of effort. The meeting had gone as well as it could have, at least. Azazel would fabricate a past for him thoroughly enough that he could enroll at Kuō Academy if he so chose, with the Gremory family being none the wiser that he was not who he claimed to be. The money and information Azazel had agreed to supply him with was just a bonus.

But for now, Mordred needed to keep a low profile until he fully recovered. With that in mind, he made his way out of the Kuō underground and made his way towards a hotel. Being in Kuō Town was a strange experience. The overall layout of the town was the same as in the future, but the town was far busier than Headquarters ever was. The lack of grim faces was certainly a refreshing change of pace though.

As coincidence would have it, Mordred did not manage to reach the hotel he had chosen for his destination without walking past a familiar figure. Hyōdō Issei was walking in his direction with two boys the same age. It took a considerable amount of effort not to sigh when he heard the three boys talking about breasts in public.

From a glance, Mordred was certain that his father had not yet become a devil at this point in time. From what little he could piece together in the future, he had not become one until the second week of April, so there was still a week until then.

As much as he wished otherwise, he could not interfere this early in the timeline. His father's death at Raynare's hands, subsequent reincarnation by Rias Gremory, and his initial reactions with Asia Argento were essential. Watching them happen and making sure some hidden variable did not change them too much was all he could do. Hyōdō Issei may have played a crucial role in the revival of Trihexa, albeit unwillingly, but if Mordred changed too much so early on, it could render all his knowledge of the future useless. Such a change was too risky. It was why he had asked Azazel and Slash Dog to let Raynare's group handle things without interference from either of them. The idea that his father would not be spared pain as a result was just a perk.

Once he passed the group, Mordred glanced back, directing a glare at the past self of his father. "You never change, do you?" So focused on his perversions, Hyōdō Issei had ended up with thirteen wives. With such a large harem and the duties he had amassed in the future, not a single one of his children had truly come to know him.

Continuing on to the hotel, Mordred could only hope that his father did not get into any trouble before his powers had recovered enough to keep an eye on him. Until then, he was on his own.