New ideas and version 2

Just a different version of Demigods goes to Hogwarts.
When Percy Jackson goes home to spend sometime with his mother. Something happens that will change his life. There were people with a tattoo on there arms.
Who are these people?
What are they here for?
Read to find out!

Cringe description IK. Just some twist and turns in this one. I have so many book ideas and I just have to write them down (explanation for why there are so many books) Anyone who have an actual plot line for this please tell me!