Percy Jackson and The Olde Olympus by knowledgechild

The Moirai smiled, not saying a thing about his thoughts. "Do you accept, Ocean Child?"

"Will I be alone in this quest? Will I face my demons alone?"

"No" The middle lady said "You shall have company to help, although it will not be the company you expect"

Percy frowned, that made sense, but, what kind of company he didn't expect? Maybe gods? Or his parents?

"What is your answer, Child?"

The smell of old, thread and forgotten got stronger as Percy thought.

"I accept this quest" And his vision turned black.

All credit goes to knowledgechild. This is their original story on AO3.
Here is the link if you would like to check it out. https://archiveofourown.org/series/4255537