The King above All Others

Highschool DxD x Male Reader x Fate Series.
Everybody thinks that Gilgamesh is the King of Heroes. That may be true, but what if there was one person, who's name is long forgotten? What if that person happened to be the very first hero in existence and the True King of Heroes? And what caused him to end up as a Heroic Spirit? Well, after a war between the Three Factions broke out, the True King of Heroes interfered and nearly killed all of the Devils, Angels and Fallen Angels. The thing that shocked the three factions, was that the True King had the Dragons on his side. But not just any kind of Dragons. No. He had the Ancient Dragon God Emperors on his side. The most powerful kind of Dragons. But even with all that power, he had to sacrifice himself to ensure the safety of humankind. Several centuries later and the fifth Holy Grail War occured. You would say that nothing special would happen, but that's where you're wrong. In that Holy Grail War, the True King was summoned by a very skilled Magus, who also happens to be the sister of a pervert and the wielder of a very powerful Sacred Gear. That fact made the True King (who was nicknamed 'The Nameless King') interested, since he was he creator of all Sacred Gears too and thought that this creation that his master wielded was lost long ago. What would happen if a certain devil were to try anything to the King's master? Will he successfully protect her? Or will he fail? Who knows.
Disclaimer: I don't own anything. Just this story.