Highschool of Demons & Priests; Book 1 Children of Light and Shadows

This is a Septiplier AU :

Gods ruled the world
The Goddess of Light and the God of Shadows Between them broke war out
The war ended with a price
With time this story vanished
but not all forgot

Many years later
Mark was a normal teenager, well that was he thought, until he came home after a day with his friends. Now he must learn to use his power and to cooperate with his demon side. For this he goes to a school, which teaches about all this stuff. There he finds lot of friends. One of them is a boy call Jack, who also has a demon, which can be sometimes a real troublemaker. But maybe they and their demons get closer then they thought at the first place. What will happen to them?
To find out read it.
The story has fights in them so sometimes it can get violent and something can be discribed in detail.
There is smut as well in this story.
So if you don't like violence or smut either skip the parts of it or don't read this book.