Name: "An Adventure Beyond Boundaries"

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DISCLAIMER: I don't own Highschool DxD and Nasuverse works, these belong to their rightful and respectful authors. The only thing I own is my OC protagonist and any ideas regarding him

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Summary : "I was just a regular guy, with regular goals, living a regular life. Now I'm the big bro of an anime character, have Demonic powers, know magic that isn't even native here, am suddenly surrounded by hot ladies, and I've got the attention of a dimension-jumping troll of a Vampire. This is just great..."

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Greetings and Bienvenue, respective readers and authors of Fanfiction. Here I have an idea for a challenge between Highschool DxD and Nasuverse works. Whoever is interested in the realization of it into a story, I had this idea in mind for some time and decided to post it. Unfortunately, I don't have time to realize it because of certain things I have, such as my lack of patience and inability to describe things in details, which is essential for fanfiction. Also, I can't be called a true fan of Nasuverse, so I might make mistakes without realizing it. For all those who are trying to mock me and make fun of me because of it, I don't give a damn about your opinion - this is just challenge for whoever is interested about turning it into the story.

The main hero is SI. Yes, SI. I know some of you don't like SI characters, but I - along with other authors - like OC main characters because it is a chance for us to realize ideas and potential that, in our opinion, wasn't brought in stories. Just look around as there are plenty of good stories with OC main characters which deserve high regards, like "Crimson Dragon Emperor and Crimson Eyed Knight" or "Kill or be Killed" written by 'Writer with bad Grammar T-T.' Also, if it comes to OC instead of protagonists of stories, then in fics, where we realize our own ideas, we just make our own OC characters under names of already existing heroes with our own preferences, as any strays from canon created by authors of real manga, book, movie and etc. automatically makes these characters and protagonists OC .

Another requirement is to make Highschool DxD more serious and fascinating, so the plot could have been better and fights more interesting.

You might ask why this isn't Vali being in Nasuverse instead of SI protagonist? Well, because I like the character of Vali Lucifer. I am fully satisfied with how he is build, based, and developed. Thus I don't see any reason to drastically change his character.

I also want to express my gratitude to such great authors like VideoGameNut and Valiant Panther, who gave PRICELESS assistance in making this challenge. Without them, you wouldn't see this work as it is now. Thanks a lot, guys!

Also, the next chapters of the challenge are ideas I am SUGGESTING. "Special chapters" are meant to give you a better expression of my idea. Whenever you include it into your own realization of this idea is up to you.

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In hindsight, I've come to understand that some of my wording in regards to this challenge may lead to potential confusion.

Allow me to clear the air on the matter.

It is not my intention to try and lead the story down a particular path. The scenes and chapter fragments shown were never meant to be considered REQUIREMENTS for the fic itself, merely attempts to gain some understanding of the protagonist and his interactions with the characters around him. Nor were his potential powers or resources all requirements, merely a suggestion of possibility, though the writer is free to pick and choose whether or not they would include them.

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This isn't only Fate series x Highschool DxD crossover, and as such, this story idea gives you the freedom to include other works of Nasuverse.

Such as Tsukihime, Melty Blood, Kara no Kyokai, Mahoutsukai no Yoru.

Now, for the sentence summaries:

Protagonist - The protagonist must – obviously- have knowledge of at least Highschool DxD and Nasuverse, particularly regarding Magecraft and its workings. The backstory may vary, but the MC would preferably be at least slightly over 20.

Protagonist preferred to have a serious profession in the past life such as a doctor, engineer, or medical technician (such knowledge would accelerate his growth with various fields).

Though this case is up for you to decide.

Rebirth - The MC is reborn as Vali's older brother with vague memories of a certain silver-haired, red-eyed man (you know who he is). Will preferably influence Vali in ways to make him stronger and somewhat more 'positive' than in canon.

I'm not sure about Vali entirely changing, but he'll probably be less arrogant and dismissive of others. If nothing else, the arrogant attitude wouldn't extend to his big brother, and he'd be one of the few people around whom he completely drops the attitude.

Experience - As Vali is adopted by Azazel, the Protagonist is essentially adopted by Zelretch and taken in as his apprentice. Reasons for Zelretch's action may vary but preferably revolve around him believing the MC (Main Character) may be capable of averting some future catastrophe and simply to alleviate his own boredom.

More likely then not, Zeltrech is just trying to troll the DxD universe.

Worlds - World travel is not necessary but encouraged due to it being a likely choice for training and entertainment by Zelretch. Recruiting people from these worlds is optional but, again, encouraged.

Please note that doing so adds more variable into the now modified DxD. Please plan out and be prepared to deal with the butterfly effect.

Holy Grail War - He will participate. Non-negotiable. What actually happens is up to you and in which universe it occurs.

If it occurs in the DxD universe, please take careful consideration when 'Holy' or 'Divine' Heroes are summoned, since the DxD universe Church has its own interpretations and the Hero Division is going to bring up questions about their ancestors/namesakes being around.

Recommended Worlds - "Campione," " Mahou Sensei Negima," "UQ Holder," "Mondaiji Taichi ga Isekai Kuru soudesu yo," "To aru Majutsu no index," " Blood Blockade Battlefront," "K Project,," "Trinity Seven," "Dies Irae."

Possibly others as long as they have the presence of some magical force, mysticism or supernatural elements.

Magic is not necessarily required to be bound to science principals or methodologies.

I know that exploring other worlds might be a bit of a tenuous thing. Because otherwise, the readers would likely start making demands or getting fussy and start saying "why didn't you add character X from series Y? You can totally do that, so why didn't you? It'd make things so much cooler for me." It might be a dangerous move , but IF you are fully sure that you can make fic with multiverse elements akin to "Twice Inheritor" written by 'bubbajack' or something as promising like "Kingdom of Hearts: War of Hearts" and "Despair War" written by 'sephiroth12285', then you can give a try , but PLEASE don't risk if you are unsure .

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Why is Highschool DxD not serious, and why should it get improved?

Alright, down to business, folks. Highschool DxD is NOT the best anime out there. Not even close. But the most disappointing thing about it is that it could actually be so much BETTER.

Not harping on the mangaka – he knew the market he was writing for – but if he just toned some parts of it down or accentuated others and added some nuance, it could have been a really great anime.

But we can't do anything about canon, so we'll have to settle with what we can do on a fic. Fortunately, I have a few suggestions.

Humanity - Let's face it, everybody, Humanity pretty much gets the short end of the stick in this series. They don't REALLY have any faction of their own. Just people like the Hero Faction who seem more interested in killing non-Humans, or the Church which is really nothing but Heaven's personal proxy force. Humanity should have a group of its own, whether a magical or even technological focus, but it should be a force OF Humanity FOR Humanity. Considering what science can achieve and the number of rogue angels and demons 'acknowledged' in the history of the cannon, it is not IMPOSSIBLE to perceive that some of them aligned with humans and/or mated with them, creating mostly human descendants with access to set factions magical abilities but not their weaknesses.

Factions - Besides what's essentially a few short cameos, there is NO attention paid to supernatural groups besides the Three Factions. What about the other Pantheons? The supernatural races like the Werewolves, the Irish Fae, the Yokai, the other mythologies of the world? The series just seems completely barren of anything besides the Three Factions, and that needs to change. Give the other groups some focus, some personal arcs to show them off and give them identity and nuance, don't just leave them out in the cold.

Peerage - For all the implications of Peerage and the Evil Pieces in the series, almost none of it is really explored at all. Someone recruits someone else into their Peerage and ... that's it. Nothing else. What about the potential abuses of power through what's essentially a feudal system? Where're the political implications and potential alliances due to certain people being offered and accepted into a Peerage? Stuff like political hostages or an overture at an alliance? Just how much power does a Peerage really grant someone when used well, and how has it really affected Devil society? The closest the issue of politics and Peerage that ever came up in the beginning of the show were the fights Riser Phoenix lost for the benefit of his family.

These are things that should really be explored but were tossed away by canon, so it's up to us writers to make up for that.

Power Scaling and Fights - Now I know this is kinda silly, considering Highschool DxD is a Shounen series material, but does anyone else think some of the fights are COMPLETE NONSENSE? How people like Rizevim and Euclid, who survived Great and Civil wars, lost to Issei? How Sairaorg lost to Issei? How Issei even managed to match with Crom Cruach? How the freaking hell Lilith, a clone of Ophis, lost to Fafnir? These fights are less fights then they are attempts to try and make Issei look impressive or build up the "New Generation" as having so much potential, and it's a real waste. These fights should be taken realistically, seriously, and it looks like the writer just isn't up to it.

If the writer chooses to maintain the 'status quo' and timeline of the story, then justifiable reasons have to be given for the victories: research into the opponent, a weakness/restriction on the opponents ends, a boost/enhancement on the protagonist side, an outside factor, a special power JUST for said opponent (such as Siegfried's specialization and bonuses against fighting dragons).