Disclaimer: I don't own High School DxD or it's related concepts and characters, but Ichiei Ishibumi and his affiliates do.
Agent of Khaos
Having found himself studying genuine Magic at a young age, Issei Hyoudou quickly unlocked his status as the Red Dragon Emperor and found himself recruited by the Hero Faction of the Khaos Brigade. Although he didn't agree with some of the methods employed by the Brigade as a whole, Issei nonetheless went along to better understand his power and have a chance to use it to protect Humanity from the supernatural.
It was after a routine observation of the Devil Peerages that attended his school, Kuoh Academy, that he met with his schoolmate and fellow Hero Magician, Le Fay Pendragon, to work on their report to their superiors among other things.
"Is there anything going on your end, Issei?" Le Fay asked as they hanged out in Kuoh Town.
"I think both of the Peerages are getting suspicious about the Fallen Angel in school." Issei replied before chuckling. "But beyond that, I don't think they've noticed us."
Le Fay chuckled as well. "Sounds about right. Want to go over it in detail over dinner?"
Smiling more genuinely, Issei brought her closer to him and said. "Sounds good to me, Le Fay."
They then kissed before looking for a nice restaurant to eat at.
I know I may have said I had some intentions of writing a DxD story, I'm now thinking against it with how full of love interests Issei's love life in canon is as well as how not all of it is adapted for the anime yet. Still, I'm not opposed to reading DxD stories that actually pull of AUs like an Exorcist to Angel Issei, a Fallen Angel-affiliate Issei, or in this case, a Hero Magician of the Khaos Brigade Issei in a good enough way.