When you were born you were born with small and short nine tails, the doctors were baffled by this and thought it was some sort of defect but your parents didn't really care and loved you, however, society didn't so you were always called a freak and so was your sister who only had one. you and her would go to the woods all the time and there you learned to control the elements. (Btw your tails gores bigger and longer as you grown)

Power is the one thing to corrupt everyone's minds: it's what most villains crave in a hero film, either that or wealth. (Y/N) knows the possible outcomes from growing in power: he might grow too corrupted to focus on his goal, however, when it comes to his goal of killing all devils, he'll do whatever it takes to become the strongest... even if that means training with Satan himself. On the other hand, his 'friends' from ORC all worry for his hatred growing stronger... add to the fact that his house was forced to be remodeled after receiving more unwanted guests, (Y/N)'s days are not exactly the best for the evil energy wielder. I don't own Highschool DxD or anything inside the show, I only own the story.

Astral Gremory is the neglected brother of Sirzech. As the years went on Astral grew more and more powerful. However this power still didn't get his family to notice him. So after all the credit for his accomplishments are given to Sirzech and that's when Astral jas had enough. He leaves the devil and doesn't return until years later.