I Make Mr D Nauseous

Percy and Annabeth's newborn daughter, Olive, was kidnapped at birth from their house in New Rome. They moved back to Camp Half blood to train new Demigods, but the hole was never patched for over a decade.
Selina Castellan is weird. Everyone knows that. She's dyslexic, has ADHD, and has one bright green eye and one stormy grey eye. At the tender age of 12 she's been kicked out of 6 schools and hasn't been able to explain the incidents that led to them.
One day a freak accident reveals that she is unable to drown, but it alerts someone of her existence. Someone who was never supposed to form a consciousness.
A new child of the prophecy is here. And her bloodline is doubly deadly.