BlaiseyWaisey
Okay, so Katie Taylor is a daughter of Poseidon who was born two years after Percy. She was kept hidden until after the Giant War and now she's discovered her heritage because of her two mothers, Jaycie and Carly (Jaycie is her birth mom). Soon she discovers that Nico di Angelo and herself are part of a prophecy-like story that The Fates devised when they first became The Fates (Which was, like, half a second after they were born.) The two of them discover that they have the ability to change what powers they can use, and the only way you can tell is the color of their eyes. (Like if Nico's eyes turned bright blue, he's in Zeus mode and can use the powers of one of Zeus's kids.) Along with Leo Valdez, they defeat an evil sorceress who has taken over the minds of the entire camp. But before all that happens, the sorceress' handmaiden, Arcaniss the magical imp sends them on a series of wacky adventures according to the whims of her mind, all taking place in various points of time, to try and keep them trapped and away from the action.
(*cough* I'm Arcaniss *cough cough* Who said that?)
DISCLAIMER: I DO NOT OWN ANY OF THE PERCY JACKSON CHARACTERS, PLACES, PLOTS, OR ADVENTURES IN ANY WAY. THE ONLY THINGS I ACTUALLY OWN IN THIS BOOK ARE THE CHARACTERS AND PLACES THAT I MADE UP, INCLUDING KATIE, HER MOTHERS, THE VILLANS, THE GROVE, AND VARIOUS OTHER THINGS THAT YOU WILL READ ABOUT AT SOME POINT OR ANOTHER.