DxD/FoZ

Male OC

Oldest son of lord and lady Gremory

Born 1600 years before canon

At the age of 200 gets summoned by Tabitha and becomes her familiar

Follows canon but has major changes due to his presence

Marries Tabitha when she becomes Queen

Uses magic to go home

Returns just as raiser and rias are getting married

Breaks up marriage

Makes Tabitha his queen with evil piece

Not harem

Must have a backbone and isn't afraid to kill people

Tabitha is at the level of high class/low ultimate class while OC is high ultimate low super devil