The 2005 novel was written for a middle school audience and understandably didn’t delve into that backstory. But Percy is the son of Poseidon, and Annabeth, who joins him on his quest, is the daughter ...

Readers' discretion is advised. In this adaption, Medusa tells her side of the story. She implies that she was betrayed and victimized by Poseidon and then punished by Athena.

Riordan also said Medusa’s defeat at the end of the episode isn’t the last we’ll see of her. “There’s a third act to that subplot of Medusa and Poseidon and Sally that you haven’t seen ...

But Percy is the son of Poseidon, and Annabeth, who joins him on his quest, is the daughter of Athena, so both have loaded lineages in the presence of Medusa.

“There’s a third act to that subplot of Medusa and Poseidon and Sally that you haven’t seen it yet. It comes in Episode 7, a really powerful flashback scene where you see Sally and Poseidon ...