the treatment of diseases, injuries, and other physical ailments with baths and bathing, especially in natural mineral waters. Origin of balneotherapy.
The name Percy originated in France. It means piercing the valley which also can mean fighting the lower side, the evil side, to reach justice. Jackson means son of Jack. I know, I don't get it either.
Percy was trapped in Tartarus with Annabeth. After fighting their way through hordes of monsters with the help of Bob and Damasen, they make it to the Doors of Death and emerge only to be knocked out by the Gian Clytius.