Just another Highschool DxD fanfic

(While playing Beyblade, my head went into a supersonic brainstorm. Until i got this idea in my head.)

Mizuki 'Gremory' Haizaki, Half younger sibling of Rias Gremory and Sirzechs Lucifer, he was born from his father Zeoticus Gremory and his mother Alisa Haizaki, Zeoticus and Venelana had a talk about his relationship with Alisa, Venelana accepted since the 2 did consider themselves as close friends to the fact that she would allow Alisa to share Zeoticus with her. After Mizuki's birth his mother died, his father took him to his family, Rias and Sirzechs considered him as their little brother, Venelana then acted as his new mother. After a few years, Mizuki got used to his new mother and siblings... although he had a very strong power which was very unknown, it wasn't even in Azazel's book of sacred gears and all of his other books. But they were all certain... this power is the most powerful if it was mastered.