Preface

This story takes place in the Highschool DxD universe, and I have made changes to the way that magic works to facilitate the crossover. If you find me unfaithful in following canonical characterizations from DxD, I am already aware of that, though I hope you will find the changes worthwhile. I sincerely hope you enjoy the story.

The story mainly focuses on three characters: Cato, the Dragonborn; Akeno, from Rias's peerage in DxD canon; and Azazel, the leader of the fallen angels, also DxD canon. Issei and the main cast of DxD do play a significant role in the story, but don't expect them to be the leading actors in the plot.

Note that this is a prologue: the events that happen in this chapter precede the rest of the story by a significant amount of time (with the sole exception of the first part of the prologue, Cato's part). It serves to introduce the three main characters from whose perspective most of the story is told.

Prologue

Cato

During the day, Kuoh city had a certain beauty to it in much the same way that every city had beauty. It wasn't special. It had stalls and stores and people, the streets were filled with the smell of exhaust and the sound of engines. The people walked silently like drones in the weekdays and chatted happily during the weekends and holidays. Nothing special, Cato mused.

The nights were different.

As bright and normal the days were, that much darker were the nights, and not because of any astronomical phenomenon that blotted out the moon and stars, no, the darkness was a tangible one that lived within the city. At night, the streets were devoid of people, and if a person was out and about, that was the sign to stay clear of them.

As a private investigator in the city, Cato had a certain understanding about how people conducted themselves. No normal person stayed out past 11, yet no one found that compulsive behavior strange. There was something larger at play in Kuoh city. Something that Cato had seen hints of in the way that the people acted, but especially so in the cases where the people didn't act, as was the case of the disappearances.

All of the victims were children between five and eight years old, and not a single one of them had been reported missing.

The families, friends, schoolmates, everyone related to the victims kept living their lives as if nothing had happened. All of them had their memories of the missing child erased so completely that the person may as well never have existed. Cato himself only discovered the disappearances by following the memory alterations, but as of yet, no one had tried to alter his memories – at least not to his knowledge.

Brainwashing everyone struck Cato as a decidedly ineffective and wild way to cover up a crime. There was always a risk that you missed someone, and ignoring that, Cato couldn't help but think that there had to be an easier way. It worked, though. Despite following the trail for two months, he had yet to find anything to lead him to the culprit.

There was no pattern to be found in the kidnappings. The children weren't special, it was a relatively even and seemingly random mix of boys and girls within the age-group, it didn't particularly target one class or ethnicity, all of it just appeared random, even the frequency of the kidnappings was random, spread over at least the past five years.

He would've been able to get further with his investigations than he had, but secrecy was of the utmost importance. Finding out the identity of the kidnapper – if it really was just one person – had been impossible, and Cato was yet unwilling to be too conspicuous in his search. They might not be enemies, after all.

Today was different from most other days. A mother had come in with a case of a missing child – her own, of course – and when Cato later sought her out, her memories were still intact. It was possible that whoever had altered the memories of previous victims was going to show up at a later point, an invaluable opportunity.

She was currently out in the streets despite it being late evening. Only a select few others were still out and about, and all of them were ones that Cato knew from previous nights. There was the group of children from the high school and academy, the vigilante who sometimes stalked along the rooftops, and a few insignificants, probably related to organized crime, that Cato cared little for. The mother was out of her element. She was either out looking for her son on her own, or someone had placed her as bait to lure someone – perhaps even Cato himself – out. It was best to be careful.

A rustle in an alley on the opposite side of the road from where Cato sat hunched next to some foliage alerted him to a newcomer, a stranger that he had never seen before. What's more, the newcomer was crossing the road toward Cato's position. Cato cast a silencing spell on himself, debating briefly whether to use invisibility as well, but deciding against it. If I can't stay hidden on my own, then I deserve whatever's coming.

The stranger was close now, pausing before he reached Cato's position and looking around. The was still within line of sight, and the stranger's eyes locked onto her before he crouched down right in front of Cato. For a while, they followed the mother, the stranger not once spotting Cato from where he was right behind him. Eventually, the mother just returned home with no complications. They sat for a few moments outside her house, a house like any other, before the stranger just sighed.

"Nothing, huh."

Cato stood up behind him, and the stranger jerked away, falling flat on his ass in surprise.

"The hell did you come from?" he said, looking hostile and ready to attack, but something clicked in his expression and he continued. "You're the investigator she spoke with, damn, I thought I finally had something."

"Why are you following her," Cato said.

"Same as you, really. You probably don't know, but her young boy isn't the first one to go missing. Far from it, in fact," the stranger visibly hesitated as he stood up. "Well, I'm sorry it came to this, I really am, but my being here must remain a secret."

A device, some sort of gauntlet, appeared out of nothing on his left hand. Cato looked at it curiously.

"At the very least I shall give you my name. I am Perseus. Rest easy knowing that I will save those children."

A flicker from the gauntlet, and Cato felt a mild wave of something wash over him, a light tickling sensation.

"What? I'm sure I…" suddenly Perseus's eyes snapped up, boring into Cato's where he stood, unmoved. He took a defensive stance, poised to strike or dodge. "You're not one of them. What, no, who are you?"

"I am Cato."

"Cato the Elder?" Perseus's stance relaxed. "Strange. To meet another hero in a place like this. At the very least, you're not behind these kidnappings. Still, I'll need you to come with me. Ophis must know."

Cato shook his head. "You're making a lot of assumptions. Now, I'm sure you understand, my being here must remain a secret."

Perseus frowned; Cato vanished from sight. "What the…?"

A knife buried itself in Perseus's side, but even so he made no sound as he jumped away from Cato who had somehow gotten behind him. A hand clutched his side where he was stabbed.

"Mystery and backstabbing ill befits a hero," he said, no hint of his injury in his voice as he drew a short sword with a hook like a sickle and a round bronze shield, polished so well that the reflection of the city lights as he held it out could be mistaken for the real thing. "And a fight does little good for secrecy. I'll forgive your attack if you agree to come with me and speak with my leader. I believe we share a goal, Cato."

Once more, Cato disappeared, and Perseus slammed his shield out behind him, hitting nothing but air. A distortion in the wind alerted him in time, and Perseus flailed out with his sword, harpe, as he threw himself down. It connected with something, but there was no sound of metal on metal, and Cato was still nowhere in sight.

There was a lull in the action after that. Perseus turned nervously, looking for any sign of disturbances, listening for any rustle. A falling leaf sprung him into motion, and he lunged toward the anomaly. Flames erupted from the ground, silent as night but bright as day, and engulfed him. The flames wouldn't hurt him, but the knife that sliced his hamstring did. This time, a stifled scream escaped his lips as magic stilled his body and he fell limp to the ground.

"A fight like this will do just fine for secrecy," Cato said, standing over the fallen hero. "We had better leave."

Cato flung Perseus over his shoulder and carried him like a sack of potatoes back to his office, fully trusting the power of his paralysis effect. Perseus had proven resilient to it at first making Cato worry about a prolonged engagement. Perseus was right that neither of them wanted a fight like that. Still, the man was a strange warrior, opting to use a shield and a peculiar blade over any sort of modern weaponry or magic. That wasn't to say there was no magic in Perseus's equipment, quite the opposite, but all of it relied, as far as Cato could tell, on the man's ability as a warrior.

Perseus was still paralyzed by the time they reached Cato's office. He hadn't even tried to shout out during the trip back despite the paralysis having limited effect on his voice. Perhaps the man valued secrecy over even his own life, or perhaps he knew more about what lurked in the night than Cato did and simply took his chances, hoping that whatever gods he gambled on would let Cato be the lesser of evils. Even if he was right, it would spell his end.

The nights of Kuoh were dark indeed.

Akeno

She held her picture of her father in her hand, the only one she had of him. She resisted the urge to spit on it and tear it apart. Without it, she had only his name and her anger. Finding him seemed an impossible task at this point, and even if she did find him, she wouldn't know what to say. Would he dismiss her out of hand, ignore her entirely? Would it matter to her if he did?

Akeno sighed and shook her head to clear it. She didn't even know why she bothered. She didn't need the bastard; she had a family now, she had Rias, and there was no place in her life for the deadbeat who abandoned her mother to die and herself to live on the streets as an outcast, persecuted because of what she was, because of him. Her heritage was a cruel memento that she tried hard to hide or forget and one that she couldn't just spit on and tear apart like the picture in her hands.

She realized long ago that looking for her father was pointless. Finding him on her own was impossible, like searching a needle in a haystack, only the needle didn't want to be found. Looking for help was equally pointless because anyone who was capable and willing to find her father would surely be someone that she should avoid, or so she had thought, but an inkling of hope had dawned within her heart.

If the people who knew of her father, who were affiliated with the fallen angels, were too dangerous to deal with because of what they were, why not just have a mundane human do the looking?

Kuoh was home to the two greatest devils that lived as part of the human world, Rias Gremory, Akeno's own friend and master, and Sona Sitri, an old friend of Rias's as well as the student council president of Kuoh Academy. Akeno herself had the misfortune of being born to a Fallen Angel father and a human mother. Crossbreeds like her were ever shunned, even more so in her case when her powers began emerging, powers inherited from her lord father.

The sign was plain enough on the front door of his office. "P.I. Cato" and on the line below, "Open". This was what she had decided on in the end. If the widely acclaimed private investigator could find her father without any association with the fallen angels, then she could have her confrontation, and if not, then fate had decided it wasn't to be. As long as the trouble of finding her father wasn't her burden to bear, she could have peace.

She gave the door a knock and waited as even footsteps approached. Akeno found herself craning her neck at the man that opened the door. He was massive. He stood taller than any normal human that Akeno had ever seen, and every visible muscle was bulging in a way that befit a strongman more so than a private investigator. Nevertheless, his mannerisms were meek and his smile pleasant as he welcomed her in and guided her over to a couch arrangement in one side of the office. The office itself was rather spacious. It was one, large rectangular room with a sizable desk opposite the entrance. In the corner there was a small table with a sink and some china, and on the opposite side from the couch arrangement were several bookcases filled to the brim with titles that Akeno could not make out, not that she particularly cared to for the sake of anything other than buying time as she put words to her feelings.

"Not often that a young lady such as yourself comes to me for help, and certainly not with such a somber expression," when Akeno kept her silence, he continued. "As you have surmised by now, I am Cato, the owner of this office. Given that you're here, I take it you have some problem – stalker boyfriend, lost relative, or perhaps someone else that you want found?"

If only it was just a stalker boyfriend, she thought. A nuisance like that was easy to deal with, all it took was a little scare with some thunder and he'd be running for the hills as though the devil himself was chasing.

"Someone that I want found, I suppose," she eventually said. "Oh, I'm Akeno Himejima, it's a pleasure to meet you."

"Likewise, miss Akeno. Now, I should remind you that, despite some of the odd rumors going about town, I can't actually bring anyone back from the dead."

Akeno shook her head. She'd heard the rumors, of course, they were what brought her here, but bringing people back from the dead was in the realm of devils, and Cato was very much human – she had made sure of that. The man in front of her had managed to make an established reputation for himself in the half year or so since he set up office. Solving a few cold cases as well as finding a boy whom law enforcement had declared dead was what made way for the rumors that he now warned her about.

"My father…" she looked down and started fiddling with her fingers. Cato seemed to sense her unease and went to make some tea in the corner. Her inner turmoil was unchanged when a steaming ceramic cup was placed in front of her along with a few small colored sugary treats. She mechanically blew on the tea to cool it before taking a sip, entirely missing its rich scent and flavor, but its warmth offered her some calm. "He left my mother when I was born."

This time, Cato picked up on her trail. "And you want me to find him for you, set up a meeting between you two perhaps?"

"I want him to fuck right off and die." She took another sip. "I just, I guess I just want to… I just want you to find him, that's all. Find him, and then I'll figure something out," he nodded slowly at that, but said nothing. "I will figure something out."

"I understand," and for the look on his face, Akeno truly believed him. But he couldn't. He might've had other customers who were looking for a missing father, she reasoned, but none of them were like her, none of their fathers were like hers. He couldn't possibly understand.

"He's… I don't know where he is," it sounded stupid, she realized. "I mean, he could be anywhere."

"Undoubtedly. Now, excuse me for not having a pleasant way to say this, but does your father know that you exist?"

Akeno's face darkened at that. "Oh, he knows. He knows."

She drained the rest of her cup. Her mother always spoke so kindly of her father. She loved him, that much was clear back then, and sometimes Akeno dreamt of him when she slept. He would come back, say words that made her feel warm, and he would smile and laugh and play with her. In some dreams, he'd never left, and they were still living happily at the shrine with no one chasing them, no one wanting them dead.

But her mother died because of him. It wasn't fair to say that he killed her mother, and yet, what difference did it make in the end? Her damned father was the reason the two of them were hunted, and he wasn't there to protect them like he should've been.

"I don't think he cares." Cato filled her cup again as she spoke. "I don't know why he left, but I don't think it was because he hated us. I think he just didn't care, and maybe we weren't worth the trouble? Maybe that was it?"

"I see. Maybe you want to ask him why for peace of mind."

"My mother," Akeno licked her lips nervously, unsure why she was opening up so much, but unable to stop herself. "She never spoke ill of him. I just don't understand. His enemies – enemies of my father, I mean – they killed her in the end after chasing her for so long. They tried for me too, but I guess they just didn't care enough to finish me off."

Cato looked stricken. "To harbor such hate for one so young…"

"Yeah, he must've been one mean guy, huh," Akeno laughed bitterly. "I often wonder – just why didn't mum hate him?"

"I will do my best to find him for you, young lady. If you know anything about him, it would be a great help."

Of course, she couldn't expect Cato to find someone with no knowledge other than well you see, he's my father, and she had prepared for this. As her fingers traced the picture, however, as they felt the rough raggedness of the paper, she hesitated. How often had she touched it, looked at it? She should've made a copy and given that, but it was too late now. She took it out, looking at it with more intensity than she ever had before. "All I have is this. And his name."

"A picture is it," Cato craned his head a little to see it from where he sat on the couch opposite hers. "Old by the look of it, but that's not a problem, I assure you. It's had its fair share of use though, hasn't it? Would you rather keep it?"

She would, she realized. She would rather keep the picture of her rotten father than have nothing save the hate.

"You needn't worry about it, young miss. If you give me the picture now, you can come again tomorrow to pick it up. I will treat it with the utmost care."

"Thank you," she smiled as best as she could despite the tears threatening to form. "And please, call me Akeno."

Azazel

The sound of metal on metal accompanied by the occasional flare or explosion was the ambience of Azazel's office. Tinkering, some might call it. An onlooker would struggle to find purpose in his actions as he split apart a trinket, hesitated, and then put it back together again with no changes made, only to repeat that same process over and over again.

The process of creating an artificial gear bordered on the impossible. The original creator of the sacred gears was long dead and deconstructing the mechanisms behind the sacred gears had proven particularly difficult. A sacred gear existed only when latched onto a living soul. When that soul passed on, or ceased to be as it were, the sacred gear went inert, its essence lost to the cycle of reincarnation. Extraction of a sacred gear was possible but ultimately tautological, as the gear needed a compatible soul for it to latch onto immediately.

Footsteps echoed through his office and he put down the strangely shaped key that he had used to open up the shell of his artificial gear.

"Don't you need some light," a smug voice came from the doorway. The newcomer was tall and handsome, with smooth skin, silver hair, and a lax attitude that would charm men and women alike. Of course, Azazel needed no light. He was a fallen angel, and the darkness was his home as much as the light.

"Vali."

Vali shrugged. "I thought you could use some company. You've been at it for, let's see, six days straight?"

Azazel shook his head. "Nonsense. But it's good enough to see you all the same. Are there any news?" his calm voice belied the anxiety he felt. There was a war brewing once more, and this time, he might not be in a position to stop it. Aggressive minorities within each of the three factions were growing more and more vocal, and there were even rumors of an additional faction gearing up for war.

"Your old brother Kokabiel stole the Excaliburs."

He perked up. "All of them?"

"One from each branch of the great church. One would think such a holy organization would be able to work together, no?"

"With the swords stolen, they might well," Azazel scratched his chin. Kokabiel was both a thorn in his side and a tragedy, but the threat he represented was limited in scope unless too many fallen brethren decided to join him. "Chances are he'll come here next."

"Oh?"

"He means to start the Great War again, I think. He'll attack the devils in the city."

All of it was conjecture with nothing substantial to it beyond a hunch. Azazel knew Kokabiel well, they had spent an eternity together, and failed to agree on anything in all of that time. Azazel wanted peace, so surely Kokabiel wanted war.

"And why should I care," Vali asked, making a show of yawning in contempt. "War might be fun, and I care little for my own kind. They feel the same, really."

"Oh, but you should care," Azazel said. "The Red Dragon Emperor wakes, and Kokabiel's plan will inadvertently snuff him out."

"And why should I care," Vali said again. "If he dies so easily, I have no interest in him."

Azazel shook his head, a smile on his face. "Ask your dear Albion for his opinion on the matter."

Albion, the Celestial Dragon. There were two of them, Ddraig and Albion, the red and the white, locked eternally in battle. They were trapped by the old God, Azazel's creator, in two sacred gears, but their battle raged on through their hosts. Throughout the ages, they had clashed many times, and each time was a calamity. Two dragons clashing was of no consequence to Azazel compared to the brewing war, however, so his battle-hungry protégé could let loose for all he cared.

"I'll take care of it," Vali said at length, though he didn't look happy with the arrangement. "When's Kokabiel coming anyway?"

Azazel huffed at that. "How am I supposed to know? You were the one who told me what he was doing recently. If we're lucky, he'll come fast. Too long and his support among the Grigori might grow too great to contain."

At times, Azazel felt that he was the only one who wanted peace. The devils were preying on humans, turning them to their side, not truly breaking the rules in doing so, but they were deeply in the morally grey. The angels too, led by the unworthy Michael, were preying on humans, as they had been since the death of God. The church misled its constituents, gathered their tithes in the name of the dead creator, and excommunicated or silenced anyone whose conduct benefitted general creation rather than just the church itself.

The Fallen… Azazel felt a tug at his heart. He understood his own failures, at least he thought he did, and they were many. His lust had broken the hearts of countless women, and the ages were ripe with his bastard children who never knew their father. Their misery fell on his shoulders. He was far from the worst, though, and it shamed him more than his own fall that his faction was the worst of them all. They didn't use the humans like the angels or devils did with mutually beneficial arrangements. The Fallen simply treated the humans as though they were worthless dirt. They raped and killed and stole as they saw fit. Azazel had stepped in to stop many of them, going so far as setting rules that they had to follow, but they fell for a reason, and why should they who forsook their loving creator listen to Azazel, who himself fell?

He sighed deeply, noting that Vali had left at some point.

How does one man stop a war?

He stopped the Great War because he had power, all of the power. It was as much out of fear as a desire for peace that he held the peace-talks. No one man should have all of that power. And yet, here he was, trying desperately to gain more power that he might stand a chance against the tide. At first, his research into the sacred gears was a way of reminiscing on his dead father. It was that way for eons it seemed, but as always, the devils spoilt creation.

The gears were made to give humans the ability to fight back. They were handed out indiscriminately to humans, not to heroes or villains, but to anyone irrespective of vice or virtue. God was like that, someone who looked at his most rotten child, never judging them, but only wondering where he went wrong, wondering how he could've done more. He had sent his son to save them all, from the most depraved slave trafficker to the hard-working slave, from the murderer to the saint, and mankind had killed him for his efforts using a sacred gear given to them by God, the Longinus.

Now, the devils had found a way to turn regular human beings into devils, warping their existence and soul into something new. Reincarnated devils. Abominations. The sacred gears, meant as a weapon for humans to combat devils and angels and monsters, were used by the devils to further their own power. Sometimes, devils even went hunting for certain individuals that possessed sacred gears of importance. But even that, Azazel mused as he went down into his laboratory, was not something he could fully condemn them for doing.

He flipped a switch by the entrance and the light turned on. Technology was what you should rely on for research, though magic still had its place. A low moan came from the sealed operating table by the opposite wall.

Research into sacred gears was so bothersome.

This is my first proper story. All feedback is greatly appreciated.