" I’m nobody’s sidekick,” Annabeth growled. “And, Percy, his accent sounds familiar because he sounds like his mother. We killed her in New Jersey.”
Percy frowned. “I’m pretty sure that accent isn’t New Jersey. Who’s his—? Oh.”
It all fell into place. Aunty Em’s Garden Gnome Emporium—the lair of Medusa. She’d talked with that same accent, at least until Percy had cut off her head.
“Medusa is your mom?” he asked. “Dude, that sucks for you. "

― Rick Riordan , The Mark of Athena (The Heroes of Olympus, #3)