The Runaway Demigod helper of all.

After the second giant war everything was normal for a bit. That's untill the gods and the campers realised that percy was becoming stronger and stronger. Zeus the paranoid jackass he is thought percy is going to overthrow him.

So after a council meeting was held with both camps present. They would have him killed. Only a few stayed loyal to him. Nico, Thalia, Reyna and Artemis, Apollo, Hestia and Hades.

Escaping before they could detain him he goes to the land beyond the gods. But what no one knows is he is the champion of hestia and hecate. Hestia right before he escaped.

But hecate when he first became a demigod, before his quest for the master bolt. She came to him and asked him to train in the ways of the wizard and he is to tell no one, not a single dead or living soul.

Since then he has trained in secret. Becoming one of the most powerful wizards without anyone knowing.

On the run hecate comes to him and tell him he should go undercover at Hogwarts and she will tell Dumbledore about an anonymous ally.
So thats where he's headed.

( Also adopted by Hades since Poseidon disowned him)