The Golden Boys (Percy Jackson X Harry Potter)

Percy Jackson always knew he had a secret twin. He just didn't know that his twin lives in London, is a super powerful wizard, and has died and come back to life to save the world. So when Percy is called to the big house under mysterious circumstances to get flashed to Mt. Olympus and hear Rachel Elizabeth Dare tell him a prophecy he has already heard in his dreams, his world gets flipped again. With Annabeth, his younger sister Charlotte and his two cousins in tow Percy has to go find his twin at a wizarding school named Hogwarts. Naturally now, Percy has to go find him or the world will come crashing down.