Percy has time. (quite literally)

When Kronos was defeated, he cursed Percy, trying to take control of him, or just to kill him.
Plot twist? The demigod, bearer of the Achilles curse, didn't die that easily, and Kronos ended up just being part of Percy's consciousness, a muse if you will.

Aka, follow as Percy learns to get along with a crazy child-eating titan while hiding it from his friends.

The story may have some errors, if you notice some, please point them out so I can correct them (unless it needs to be that way for the story).