I: Learn to Fly

After an incident with a monster he knew nothing about, Percy was stuck in Purgatory with all the creatures out hunting for his blood. There, a certain human might be his only hope for getting out of the place. But after the portal, there might be more troubling matters awaiting him out in the wrong world. And the demigod is alone. Season 8 rewrite.
[Percy Jackson and Supernatural crossover]