medusa's lair

3

The Original Trio

“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, The Reef Crowned

Hesiod and some other sources portray the Gorgons as sea-demons, and one of the most perilous predicaments of seafaring ascribed to them was reefs. Medusa was specifically connected to reefs as they are said to have sprouted from her severed head where Perseus had laid it on a beach.
And speaking of Perseus, he’s stone cold dead in this story, as in a last desperate effort to protect their mortal sister, the Graeae had her petrify their one mystical eye, a charm which then allowed her to see beyond all deception, god and man’s alike.
Without knowing this, Perseus stalked into Medusa’s lair certain of the safe cover of Hades’ helm only to find her calcifying eyes cutting straight into his own.
Then she went to the beach with her head still perfectly attached ;)