Phoenix arrives in Highschool DXD universe. Let's just hope he does not go Supernova, when some idiot devil tries to get him into the peerage... Welp, they are doomed I suppose.

"Power is something that has existed far before the idea of time came to be. It is the maker of kings and tyrants, of devils and of gods. But like all good things, it comes at a cost; be it of material or immaterial nature, something is always taken in exchange. Some will pay it willingly, while some have no choice. Can you guess which I am?" (Rewrite of 'An Ancient Defender'.)

Radiant and Dire. Two forces locked in never-ending war. But all things have an end, even the two Ancients were aware of the unavoidable dusk. In an act of unified desperation, both Ancients sealed themselves and their soldiers into a host that would be sure to attract enemies. And who better than the Crimson Dragon emperor himself. BAMF!slightly disturbed!Issei. IsseixHarem