The Oddity (A Percy Jackson/Harry Potter crossover)

Perseus Jackson was a strange person, Harry decided. He came from overseas, had the weirdest American accent, spoke strange sayings, had ADHD and dyslexia, and stood up for every kid. He was a Gryffindor, but consorted with Hufflepuffs, Ravenclaws, and even Slytherins. Perseus Jackson was a weird person, Harry Potter...

Vanishing Seas (Percy Jackson and supernatural)

Percy Winchester, according to John winchester, went missing when he was 12 during an undercover hunt at Yancy Academy. But when Sam and Dean see a boy that looks suspiciously like their adopted brother flying down a hill on a silver platter some questions must be asked about the truth behind Percy's disappearance.