Bio and Sacred Gear

This is my first story so please don't criticize me, and the art isn't mine, and this will be an ongoing story, I will be adding other characters from different animes to this story as well. This story is based off of my 2nd Highschool dxd au.
In my 2nd highschool dxd au, Grey has a blood related twin brother, Grey's brother will be added to the story and Grey's brother will get his own harem if that is what you all wish, leave comments of who should be int that Harem.

Will Grey Fullbuster find out who his real parents are? Will Grey meet his twin brother?