@Czechoslowak I just watched the wiki and the main problem of your old story is that the two worlds weren't mixed properly. it would have been necessary to integrate Infamous elements as and when and this from the first chapter
in Infamous, the Conduits are ostracized, hated, hunted down, tortured, killed!
I didn't find this apocalyptic "mood" in your old story, just a normal Dxd story.
Rias too easily accepts a mutant she might hate?
even for Issei and other humans. (oddly enough this makes more sense than the majority of betrayed, abused, bullied male readers stories)
https://www.fanfiction.net/s/12473975/1/inFAMOUS-Red-Dragon-Conduit
it's the only story I could find, unfortunately there are only two chapters and the story seems sadly abandoned.
Issei is a conduit while being The Red Dragon Emperor.
hoping it helps a little, good luck!