Okay . Soooo of you're gonna write a cross over (ex: Pjo-Hp)
You need to have a good back ground story to make it realistic . Like (example above) Percy Jackson goes to Hogwarts to protect the "boy-who-lived" in hecates pet world . Because Godrick Gryffindoor ,Helga Hufflepuff , Slazar Slytherin ,and Rowina Ravenclaw were children of hecate. So you need to have a back ground story . And it needs to be realistic with the story. You just gotta do that , but try to be creative with it, and you'll be fine with a cross over . BUT you have to follow the story line while you alter it to fit your story ,you can't change it so much that it would affect the outcome of the book . (Ex. You cannot save a main character that dies : Fred Weasley, Sirius Black, Luke Castellan,etc.)
