AN: So, I was browsing through the Ars Goetia and looking up the traits of the 72 pillars when I came across several interesting things about the Gremory, and seeing that I was in the mood of some Fate and DxD I crank out this new story of mine.

Simply put, surprise everyone.

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Chapter 1: Life as a Devil.

Shirou Emiya died and had being reincarnated as a Devil in this new world.

He died years after the Fifth Holy Grail War after living a long life and saving countless people and becoming a modern day Hero in the eyes of the world, in both deed and name. The people loved him for his heroic deeds and while many tried to undermine him, Shirou along with the help of his many allies, was able to weather the betrayals and conspiracies.

He had really been lucky to have so many wonderful women as his friends who supported him in thick in thin, never leaving his side and supporting and respecting his decisions. Shirou knew that his path as a hero had caused them too many complications but they never complained and instead berated him for been such a worry wuss.

He truly had been lucky to be gifted with such a wonderful friends which was why at the age of 86 years old the world finally said it was enough and sought to balance the Karmic scale by making him fight an army of literal Shoggoth summoned by deranged mad mages that tore his soul with their psychic screams, mutilated his world of infinite blades by ripping it apart at a conceptual level and using it as bridge to other worlds and realms of endless horrors.

In the end even though he had won and beaten them, his reality marble had become a literal doorway to the realm of horrors that were slowly but surely encroaching his mind tearing his soul apart and unleash themselves into the world.

Zelretch the master of his Rin and Luvia and a dear friend and mentor offered his help to him and while he could not fully repair his soul and reality marble, he could reincarnate it into a world that would allow his soul to heal and his reality marble to recover allowing him to live another life without endangering existence itself.

Death was not an option as the horrors in his mind new of so many necromantic and soul rendering abilities that would simply puppet his dead body and reality marble and tear their way out into the world.

Reincarnation would stall them as they could not cross the boundaries between so many worlds and dare face their powerful guardians.

The catch was that…Shirou would no longer be human.

It was his human shell that was keeping the horrors at bay but only just, only just. If Zelretch reincarnated him as a human baby the eldritch monstrosities would simply corrupt his still developing mind and not even his vast experience with the horrors would be able to protect him truly.

Thus in order to keep those monstrosities at bay Shirou had to become a monster, in both body and soul but in doing so, Shirou could never enter the Throne of Heroes, for he would forever serve as a living prison for the horrors till the end of time and more.

It was ironic, that humanity's greatest modern day hero had to become a monster in order to protect them and not only that but he would forever be barred from entering the realm where heroes reside and watch over them for to keep those monsters at bay, Shirou could not afford the peace of death and had to live out for all of eternity and beyond as the jailer guarding the monsters that now resided in his soul.

It was just too much to ask of him, just too much and thus naturally, Shirou accepted it with a smile.

"Shirou, forgive me for not being able to help you." Zelretch said as he prepared to send him to another world.

"There's nothing to forgive Zelretch." Shirou said, smiling even as his mind corroded under the assault of the endless horrors. "Can you do me a favour?"

"Anything old friend." Zelretch replied, as he powered his spell.

"Can you tell Rin and Luvia to take care of the others and not wreck the house in the process? Also tell Sakura to keep the two in line, god knows what they would do if she was not there to mediated their fights." Golden wisps of light shone into existence illuminating the cold artic wasteland.

"As for Lorelei, well tell her that I'm sorry I won't be able to come to her grandmother's birthday and cook for her." Multi-coloured light followed the golden wisps as they formed an aurora.

"Tell Gray to be careful in her investigations will you. She really had become a bit hardheaded like me over the years." Shirou laughed as the golden wisps of light entered his body.

"Also tell Maya to go easy on the kids, god knows Tatsuya and Miyuki need it what with those elders pushing them hard." His body glowed in ethereal light, as it broke down into tiny blades.

"Tell Ciel I won't be making her favourite curry again, tell Aoko to be careful in her fights, tell Arcueid to not cosplay too much and tell…"

"…tell…tell everyone I'm sorry that I won't be coming home, but tell them I was happy to have been their friend and got to know them, tell them I am proud to known such great women who supported me through thick and thin and tell them…tell them I am sorry I could not return the love they had for me." His face cracked as releasing a golden glow.

"Maybe in another life, another time, I could have loved them as much as they love me. So, tell them I was happy to have gained their love and am sorry I could not love them back." Shirou said as his body turned into golden dust, his soul travelling into a new world to live out a new life.

"I will." Zelretch said, looking onto to the aurora that would take his friend into a new world. A world where god is dead and Devils, angels and the fallen are locked in an uneasy peace.

"I will, Shirou. I will."

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Shirou woke up, he had been dreaming again, dreaming of his past life.

He really did not want to think much about it but Shirou did miss his old life, his old family and children.

But he did not dwell on it much as he had long accepted that he might not ever see them again and it was his decision that separated them from him and thus he would continue doing his duty and keep the monsters at bay and living out his new life as a devil named William Belial.

Yes, Shirou was a devil in this new world, the same devils mentioned in the bible. Not only that, he was born as the son of a members of the 72 pillars of the underworld, Zeoticus Gremory and Carla Belial, giving him a mixture of red hair with white snowy streaks in between, it was like fate was taunting him about his past life and reminding him about his bastard alternate future self as Archer.

Even his devil powers were like a slap to his face that kept reminding him about his past.

Shirou had not inherited the vaunted vast magical reserves of the Gremory family but he did inherit the ability to read the past, present and future of the object and altering the object and imposing a future timeline onto the object or recreate the object using his devil powers. It was like someone had taken his past tracing and alteration spell and simply pushed it up to eleven.

The fact that the house of Gremory was represented by swords on the Tarot card amplified his affinity with swords in general making it easier to recreate swords with his power.

Not only that but he had somehow inherited the 'worthlessness' power of his mother's family too which when used in conjuncture with his Gremory family power proved to be broken as hell.

One power gave him supreme knowledge about an object while the other allowed him to nullify any power that he had in depth knowledge about, effectively making him the greatest threat to magic user and thus it would not be out of the ordinary to call him a Magus Killer due to his powers.

Fate really seemed intent on reminding him about his past life in a very perverse manner.

Ciel would really have a time of her life if she was aware of the condition of his new life.

It was good thing his parents were unaware about his powers as he did not want the world to focus their attention on him and inevitably find out about his reality marble and the numerous legendary weapon housed in it. Not to mention, that there were still some holes and tears in his world and soul that still had to heal before he could safely use it.

The tears and holes were slowly healing but in return his reality marble now housed a multitude of gods, angels, fallen and other various mythological beasts and eldritch monstrosities from across the multiverse. Heck he even found some literal fictional characters that he recognised in his reality marble and some copies of heroic spirits too.

How did that happen? Well it was simple, when the Shogoth used his reality marble as a bridge to other realms it attracted the attention of the gods, devils, demons, angels and other powerful beings of various realms and universes who sent their agents to check on it and prevent their counterparts from breaking free and wreaking his universe.

The angels and other holy beings and gods lend their aid in keep the eldritch monsters and devils in check and from fully corrupting his soul and while being born as a devil should have made them wary of him and garnered the favour of the demons and devils. It had instead made the angels and gods look at him in a more favourable light and garnered the scorned and hate of the residents of hell.

Still the forces of various heaven and hell did not seek to kill each other as they were immortal in every sense and could not be killed in any way and even allied together to keep the more eldritch monsters in check.

They could have gone back before his soul healed but they chose to stay as they were but mere copies of their original counterparts and could afford to stay back. Some of them the angels included were quite eager to explore the new world and test the residents of the Supernatural realm too.

"You know Shirou, you really should try to contact your father and your half siblings and tell them of your power." One of his RM residents said, as he got dressed. "You really deserve to take on the name of Gremory and show the power of a true Gremory to the world."

It was none other than the fame Duchess Gremory, one of the 72 pillars of hell and his adopted ancestor. Having long brown hair and violet eyes, she was a far cry from the Gremory of this world but nonetheless was the rightful owner of the title.

She was one of the few demons that Shirou got along with and even the angels did not try to limit their interactions as they respected his now devil bloodline and acknowledge their distant relationship as family.

"No thanks, Gremory, I am happy with my current name and I rather not take on the Gremory name and bring in unwanted attention onto myself." Shirou replied, looking into the mirror and adjusted his tie. It was really strange that Shirou looked eerily like his past self, with the red hair and white streaks and he sometimes forgot that he was no longer a human despite how human looking his new body was.

It was only his grey silver eyes that reminded him of his new life and reminded him that he was a creature of hell.

"Why not Shirou, it is not like you can't defeat every foe you meet with your powers and that too is without going into detail the powers of the angels, gods and devils that reside in your soul. Why should you be afraid of those pretenders who parade the name of Gremory but are actually the devils of Bael?"

"You know why, honoured ancestor." Shirou replied with a smirk, knowing how she hated being reminded of her apparent age.

"Stop calling me that!" Gremory shouted and Shirou knew even without looking that she was sporting a few tick marks and gritting her teeth. Who knew that the famed duchess was so easy to tease?

"No it is just that you are a damn womaniser, like Solomon." Kokabiel, the noble star of heaven, said as she entered the conversation.

Angels did not have a human like appearance nor did they have a gender at all, being neutral and above such things but overtime the angels had taken the appearance of humans like the seraphs to make it easier for him as they knew that their true appearance was just too much for his mind to comprehend.

Kokabiel had taken the appearance of a blue haired girl with a bob-cut and wore round glasses and held a book to complete the scholarly librarian look she was going for.

She was one of the angels that best got along with him as they often tried to have matches to see who could divine the future best as he competed with his powers to look into the future of the objects while the angel divine the future with the help of the stars and the heavenly bodies in the sky.

How she was able to sense the stars and heavenly bodies when they were in the underworld, a realm away from the material universe as something of a mystery but Shirou chalked it up as her being an angel and it being under her preview.

"I am not a womaniser Kokabiel and I am not seducing my adopted ancestor." Shirou replied. Somehow the devils, gods and angels had gotten into their heads that Shirou was a womaniser and was seducing the beings in his soul.

"That's not what your past life looked like." Cu Cullian said, as he laughed and drank with Indra and Bacchus, who seemed to have no shortage of wine with them. Shirou was really glad that he had some gods of food, wine, music and other miscellaneous things inside his soul as he knew that it would have been way too much for him to bear hearing the complains of hungry, thirsty and bored divine beings.

It still did not make up for the insane parties that kept on going for days and the numerous fights that kept breaking out. Sometimes Shirou really hated the fact that his residents could not die and thus he was stuck with them forever, listening to them partying and fighting in his mind.

"Tsk." Shirou gritted as he knew that the hound had gotten him but he definitely was not seducing his ancestor damn it.

"Ignore him, master." Tamamo voiced out from somewhere. "I am sure you will remain faithful to your love and not consort with demons of hell."

"Too late for that don't you think? He is a literal devil in this life." Beelzebub snorted, he was one of the few seven princes that had entered his reality marble and could not escape in time as he was imprisoned here by angels that were way stronger than the ones in his universe.

Still his power of 'Devour' made him life up to his rank as one of the rulers of hell.

"But that does not diminish his accomplishments as a human in his past life. And to be honest can you really say that the devils of this dimension are any different than humans." Kokabiel retorted, she really did not care about his species and for her and the other angels he was still a human in their eyes.

Beelzebub growled at being reminded of the fact and even some of the fallen angels growled at that bit. They did not like how human the Devils of this world were and while they were powerful in their own right, the demons and devils of other universes were just far too powerful compared to the devils of this world.

They regarded Shirou as a devil in only name and only when he could beat them in an all-out fight without the aid of the angels and gods will they acknowledge him as a true devil.

Heck the fact that the seven of the four rulers of hell had died in the last war had proven to the demons and devils in his reality marble that the devils of this dimension were freakishly weak by their standards.

Every devil and demon worth their name could regenerate given enough time and they were only banished from earth and lost their physical forms and were reborn in hell. Not be killed like a mortal nor even be reborn in purgatory or hell.

Despite them looking down on the devils, some of the demons and devils did admit that the four Satans were powerful but not worthy, never worthy of the titles they would hold and impeached Shirou to never refer the four Satans by the titles they wrongfully inherited and ordered him to refer them only by their birth names and status.

This was a bit hard for Shirou, seeing that he was the half-brother to one of the ruling satans of the underworld, who was also considered the de-facto leader of the devils.

Still as a bastard child of Gremory Shirou did not have much contact with his two half-siblings who carried the Gremory name with them and live in anonymity for the most part, though Shirou had a feeling that his elder brother knew of his existence and if he did not than Shirou would be really be disappointed as the Gremory were famous for caring about their families and Sirzechs being the leader of the Devil at least had to know about his family and his relatives.

Shirou knew he must have more half-siblings due to the huge harem his father had but he was unaware of their existence as he had been living a quiet life in the Gremory lands and his mother was not too fond of the other members of his father's harem and thus did not visit them much.

After checking that he was fully dressed Shirou headed down to meet with his mother.

"Good morning mother." Shirou greeted his mother, Carla, a silver grey haired women who while was centuries old looked like she was in her mid-twenties and at the peak of her life. She resembled quite like the Einzbern homunculus and were it not for her grey eyes Shirou would have easily mistaken her for one.

"Good morning, William. So, ready for the big day?" Carla asked as she readied the breakfast table.

Now why the hell was not Shirou cooking and letting his mother doing the cooking? It was simple, never get between his mother and her kitchen, she could make the shoggoth know what fear meant and she DID make them tremble before her wrath. Not that she would ever know about it.

"Yes mother." The big day, she was referring to was him finally getting the permission to get a peerage, which Shirou saw no reason to build one and get a permit to live in the human world which was honestly what Shirou was most excited about.

It had been a long time since he had seen the human world and it was going to be like a blast to the past considering how long he had lived in his past life and had seen the world undergo so many changes.

"Oohhh…I am so excited that my son is going to get his first Evil Pieces." Carla said as she began to cry, "and…and he is going to leave his poor mother for his harem." This time she openly wailed.

"Mother! I am not going to build a harem!" Shirou shouted, 'Why does everyone thinks that I am the next Solomon?!' it was one thing for the devils in his soul to say that but even his mother.

"I…'sniff'….know you too well, William…'sniff'…you are just too kind and considerate for your own good and have a damn hero complex." She said making him wince at that, he was not that bad. "I would be rather surprised if the first member of your peerage was not a girl or at least half your peerage did not make up your peerage by the time you completed your set." Carla said with narrow eyes and Shirou could only sigh in exasperation at her antics.

"Don't be so dramatic mother."

"I'm not, I just know my son too well." Carla said as she gave him a beaming smile. "Now be a dear and eat your fill William."

Sighing, Shirou took his seat and began to dig in like Saber dug in when he had cooked for her. His mother's cooking was just too damn good, so good that she had created an entire magical discipline based on cooking to make up for her apparent inability to use her family magic. The same brand of magic that she had taught Shirou over the years which he had not only mastered it but had also begun to improve upon the dishes and the effects of the cooking.

Carla's cooking had won the heart of his father and she had told him time and time again that it would also win him the heart of his future spouses.

'Oh some magical booster meals? Mother is really going all out today.' Shirou thought as he ate his breakfast, while thinking about how the day was going to go.

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'Well, that was anti-climactic.' Shirou thought as he exited the office with his Evil pieces and permit. The process was rather simple, Shirou just had to touch a small tome to register and he was given his Evil Pieces by the clerks and escorted to another office to get his permit.

All in all it was a short and simple process, though he had been expecting something more out of it.

It was not like he was angry or anything, it was just that the whole process felt so…underwhelming.

Regardless of this Shirou had gotten what he came for and in just a few days he would depart for Earth and live under his new alias Shirou Emiya. The whole thing seemed like a joke to him as the office had asked for an alias by which they would register him in the human world and not his devil name, which made sense once he thought about it as it would allow him some added protection in the form of obscurity from devil-hunters and other enemies of devils and allow him to live out an ordinary life if he wanted.

Not only that they had also asked him which country he would like to be live in and thus William Belial became Shirou Emiya based on Kuoh and would be entering Kuoh academy as a second year student, which interestingly was also the base of operations for his younger half-sister Rias and the younger sister of Serafall Sitri, Sona.

Kuoh was not his first choice of residence but it was the only Devil territory in the entire Japanese isle which said something about the power of the Shinto Pantheon as the Devil held vast territories near the Vatican City itself, the heart of the Church.

Or it could be that the devils were not interested in the Japanese isles to begin with. He was not sure which was more likely.

After a few days Shirou bade goodbye to his mother and was off to Kuoh, where he hopefully not be dragged into any shenanigans, but considering how he was fate's chew toy, Shirou knew that he would never have a quiet life.

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AN: So Yes this is a thing. Who knew that this was totally possible huh?