The Teases and Spoilers of Episode 4
Percy Jackson and the Olympians episode 4 hinted at a major villain for a sequel series, which could possibly mean 10 more seasons set in this universe. Aside from future teases, Percy Jackson episode 4 was packed with story reveals. The ending of Percy Jackson episode 3 left the titular character, Annabeth, and Grover continuing their quest to Los Angeles and the entrance to the Underworld, with episode 4 seeing the trio travel across the country on a train. However, this train ride is quickly disturbed by the appearance of another pair of Percy Jackson's Greek mythological creatures. After encountering the Furies and Medusa in the episode prior, Percy Jackson episode 4 introduced the Chimera and the monster's mother, Echidna. During this confrontation and the ensuing chase, plenty of story reveals are divulged about the world of Percy Jackson, including Athena's judgment, Annabeth's backstory, and the tease of a future series that acts as a sequel to the original books by Rick Riordan.
Percy Jackson collage with actor Walker Scobell in foreground and Heroes of Olympus books in background.
The tease found in Percy Jackson and the Olympians episode 4 comes when Echidna mentions that her grandmother is also the great-grandmother of Percy. The character being referenced in this dialog is Gaia, the primordial goddess of the Earth, who serves as the primary villain of the Heroes of Olympus book series. After Percy Jackson's five books were released - the final one in 2009 - Rick Riordan began writing Heroes of Olympus as a sequel which also consisted of five books. As such, the tease at Gaia found in Percy Jackson and the Olympians episode 4 could be hinting at nine more seasons with a 10th potentially being based on Percy Jackson and the Chalice of the Gods, a book released in 2023 set after Heroes of Olympus. While it remains likely that the four other Percy Jackson books will be adapted as Percy Jackson and the Olympians' second, third, fourth, and fifth seasons, Echidna's line in episode 4 subtly sets up more stories to be told after that.
Percy Jackson looking confused next to Kronos in Percy's dreams in episode 4
What makes the tease of Gaia found in Percy Jackson episode 4 that much better is that it matches the understated nature of Kronos' set-up. While Gaia serves as the primary antagonist of Heroes of Olympus, Kronos is the central villain of Percy Jackson and the Olympians. Thus far, the set-up of Kronos has been largely confined to dreams and smaller references that elevate the characters and story of Percy Jackson season 1 rather than overt, jarring foreshadowing. The same can be said for Gaia, as the line from Echidna could easily be dubbed a throwaway reference to the interlinked relationships found in Greek mythology. The Gaia reference will only be caught by fans incredibly familiar with the Percy Jackson book universe, with the line serving as a way to add tension and stakes to the encounter with Echidna for those unaware of who Gaia is. As such, Percy Jackson and the Olympians episode 4's teases at future villains remain suitably understated, so as to not take away from the story being told involving Percy, Annabeth, and Grover and their encounter with Echidna and the Chimera.