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Irrational Fears are illogical fears that most demigods, daemons and immortals are sometimes plagued by. Demigod fears are often based on their parents' stories or sometimes in traumas they had when they were young. They are caused by Phobos.

Known Fears

Children of Poseidon

The demigod children of Poseidon have claustrophobia, a fear of confined spaces. It is because the sea is so open, free, and wild. Percy mentioned his claustrophobia in The Lightning Thief, but it doesn't seem to bother him in The Battle of the Labyrinth. It could simply be that they become restless when confined, but are still functional and it only acts as a mild annoyance. It may be a mistake of the author.

Children of Athena

The demigod children of Athena have arachnophobia, the fear of spiders. They fear spiders because of the story of their mother and Arachne, with Arachne's children seeking revenge for their mother as a result. Annabeth's arachnophobia is more acute than even that of her siblings because of her childhood experience with them. Her fear of spiders shows itself many times during the Percy Jackson & the Olympians, & Hero's of Olympus series.

Children of Hephaestus

The demigod children of Hephaestus have acrophobia (fear of heights). It is because their father was pitched off Mount Olympus by Hera as a baby. It is mentioned in The Ultimate Guide. However, neither Leo Valdez or Charles Beckendorf, two sons of Hephaestus, show signs of fear while flying.

Children of Aphrodite

The demigod children of Aphrodite have a mild case of cacophobia (fear of ugliness) and/or not looking perfect all the time. Piper McLean, however, is one of the extremely few exceptions.


Satyrs are afraid of caves and underground locations. This is because they cannot tell if there are monsters nearby, as the underground smells like monsters to them at all times. However, Grover Underwood was able to overcome this fear, having journeyed to both the Underworld and the Labyrinth.

Unique Fears


After being imprisoned in Otis and Ephialtes' Celestial Bronze jar for thirteen months, Ares developed an extreme fear of jars and imprisonments.

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. After nearly dying in a muskeg in Alaska, he developed a fear of suffocation so intense, that it actually made him wary about traveling underwater, despite knowing that he can breath underwater. As The Mark of Athena progresses, Percy comes to believe that his fear is not just of physical suffocation, but of being "suffocated" by the burden of responsibility for his friends' safety, which he places on himself.

Annabeth Chase

Annabeth Chase has an intense fear of Cyclopes. It can be traced back to when she was travelling with Luke, Thalia and Grover to Camp Half-Blood and got trapped in a vicious Cyclops' lair, which indirectly caused Thalia's transformation into a tree. Hence, Annabeth initially had problems with Tyson, but she eventually got over this in The Sea of Monsters. Annabeth also has an immense fear of spiders, because of the infamous story of her mother, the godess Athena, and Arachne. When she was living with her father and step-mother in San Fransisco as a little girl, they'd often crawl around her, bitting her and putting webs on her, while she was in bed. She eventually is forced to overcome this fear in the Mark of Athena.

Luke Castellan

Luke Castellan has an intense fear of Cyclopes. It can be traced back to when he was travelling with Annabeth, Thalia and Grover to Camp Half-Blood and got trapped in a vicious Cyclops' lair, which indirectly caused Thalia's transformation into a tree.

Nico di Angelo

Nico's greatest fear is of someone finding out about his homosexuality. Therefore, he never stayed at either camp for long and didn't make connections of friendship with most people to keep them from finding out, becoming more isolated than any other demigod. This fear about not being accepted due to being gay most likely comes from Nico growing up in the 1940s, when "non-traditional" sexual orientations weren't accepted. Hence, in The House of Hades, when Cupid forcibly makes Nico reveal his secret in front of Jason, the former is nearly reduced to tears. When Reyna accidentally learns about his secret in The Blood of Olympus, she doesn't judge him, and still accepts him as a friend just as he is (though she is still very surprised at this revelation), supporting him without hesitation much to Nico's surprise and relief. This unconditional acceptance and support was what most likely gave Nico the courage to finally come out to a very surprised Percy and Annabeth at the end, indicating that Nico has finally begun to overcome this immense fear and insecurity of his.

Another fear Nico has is Nyctophobia (fear of the dark). This is because after transporting the Athena Parthenos to camp half-blood together with coach Hedge and Reyna, he slowly faded away in the shadows. He was helped by Will Solace. Now he is afraid of the dark, because he might melt into it permanently.

Thalia Grace

Thalia Grace has acrophobia (fear of heights), as shown in The Titan's Curse. This is ironic because she is the daughter of Zeus, the god of the sky. She is rather ashamed of this fear of hers as a result.

Grover Underwood

Grover Underwood has an intense fear of Cyclopes, fearing that he will be eaten by them. It can be traced back to when he was leading Luke, Thalia, and Annabeth to Camp Half-Blood, but took some wrong turns in Brooklyn and got trapped in a vicious Cyclops' lair. Then, there was the time Polyphemus was going to eat Grover, an horrifying ordeal that the latter barely escaped. Hence, Grover initially had problems with Tyson, and the feeling was mutual, but they both eventually got over this, with Tyson ultimately helping him find Pan.

Additionally, Grover has an odd fear of rabbits, leporiphobia, which Thalia jokingly calls his "bunny-phobia." His reasoning for it is because bunnies "steal carrots from defenseless satyrs."

Clarisse La Rue

Clarisse's greatest fear, as implied in The Sea of Monsters and mentioned in The Demigod Files, is paterphobia, or more precisely, her father Ares threatening, scolding, and punishing her, as the god of war is infamously ferocious. However, with some encouragement from Percy, Clarisse was able to overcome it and overpower Deimos.


Tyson is afraid of Grover (who, coincidentally, is scared of him), mainly due to him sneezing from the latter's goat hair. However, while in the Labyrinth, Tyson goes with Grover to help protect him, while they search for the lost god Pan. After this quest, the two seem to be on much better terms with each other, with Grover even cheering for Tyson after the latter helped defeat Typhon.

Furthermore, Tyson is very much terrified of everything related to death, such as the skeleton warriors aboard Clarisse's ship and initially Nico di Angelo.

Frank Zhang

Due to his life force being tied to a piece of fire wood, he has pyrophobia, causing him additional problems when dealing with Leo. However, after Leo provides him with a fireproof bag in The House of Hades, Frank's pyrophobia is almost completely overcome as a result. Frank also greatly fears Nico di Angelo (to the point that he doesn't dare to ask him personal questions and is terrified of going anywhere alone with him), even though he knows that the son of Hades is a loyal ally, as the brother of Frank's girlfriend. By the end of the series, however, Frank's fear of Nico seems to have greatly decreased in magnitude, as Nico approves of his relationship with Hazel, and Frank (as the new Praetor) makes it clear that Nico is always welcome to visit Camp Jupiter.

Magnus Chase

Magnus suffers from lupophobia, fear of wolves. When Magnus was fourteen a pair of wolves attacked his apartment and killed his mother. Since then he's been terrified of them. He shied away from the "cleaning wolves" at the Hotel Valhalla and was terrified when he faced Fenris Wolf.