Irrational Fears

Irrational Fears are illogical fears that Demigods are sometimes plagued by. Demigod fears are often based off of their parents' stories. They are caused by Phobos, as shown in The Demigod Files.

Aphrodite's cabin
The demigod children of Aphrodite are afraid of not looking perfect all the time they are also afraid of not being fashionable.

Athena's cabin
The demigod children of Athena have Arachnophobia, a fear of spiders. They fear spiders because of the story of Athena and Arachne. This is because Arachne's children seek revenge for their mother. Annabeth's fear of spiders shows itself many times during the series.

Hephaestus' cabin
The demigod children of Hephaestus have Acrophobia, a fear of heights. It is because their father Hephaestus was pitched off Mount Olympus by Hera (who blames Zeus) as a baby. It is mentioned in The Ultimate Guide. This is strange because Leo Valdez, a known son of Hephaestus, flew the Bronze Dragon, Festus.

Poseidon's cabin
The demigod children of Poseidon have Claustrophobia, a fear of confined spaces. It is because the sea is so open and free. Percy mentioned his claustrophobia in The Lightning Thief, but it doesn't seem to bother him in The Battle of the Labyrinth.

Satyrs
Satyrs are afraid of caves and underground locations. This is because they can't tell if there are Monsters nearby, as the underground smells like monsters.

Grover Underwood
Grover Underwood has a fear of Cyclopes. He is afraid he will be eaten by them. It can be traced back to when Polyphemus was going to eat Grover. Grover also has problems with Tyson and the feeling is mutual. Grover has a fear of rabbits which Thalia calls his "bunny-phobia". Grover mentioned that bunnies "steal celery from defenceless satyrs".

Percy Jackson
Percy Jackson is afraid of The Great Prophecy. It is shown in the The Demigod Files story Percy Jackson and the Stolen Chariot when Phobos makes Percy see his worst fear.

Thalia Grace
Thalia Grace has Acrophobia, a fear of heights, as shown in The Titan's Curse, despite being the daughter of Zeus, the God of the Sky. Percy finds this ironic.