The Quest of Hecate

Will, Nico, Leo, Percy, and Jason are dismayed to find that they are sent on yet another quest. By Hecate. Wonderful (note the sarcasm). They are sent to Hogwarts, disguised as wizards, and at no cost, should they reveal their godly heritage.
They have to protect Hecate's favorite wizard, Harry Potter, from Death Eater's out for revenge.

CHARACTERS ARE NOT MINE; THEY BELONG TO RICK RIORDAN AND JK. ROWLING