Eye of the Ocean

Percabeth's child, a reincarnation of Bianca Di Angelo, grew up not knowing her true identity as the daughter of the two most powerful demigods in history (and also olympus's number 1 demigod couple). At age twelve, a centaur shows up at her doorstep, showing her family,. However, time is running out. She has 12 days, until the winter solstice, where she would either be happily celebrating her birthday, or watching the downfall of Olympus from the foot of her grandfather's throne.