I don't know, Percy, but every hero has one. If you don't find it and learn to control it ... well, they don't call it 'fatal' for nothing.

Annabeth Chase talking about fatal flaws, in The Sea of Monsters

Fatal Flaws are mental or physical weaknesses that demigods, humans, and immortals possess. These flaws can often cause the downfall of the being, but are particularly dangerous to demigods. In Greek plays, they are often referred to as "Tragic Flaws".




Fatal Flaws are first mentioned in The Sea of Monsters when Annabeth Chase wants to listen to the Siren's song to learn her fatal flaw. She then explains to Percy Jackson what fatal flaws are. Fatal flaws are mentioned frequently throughout the series. Percy's flaw is personal/excessive loyalty, which was told to him by Athena in The Titan's Curse. She says it is a dangerous flaw for the hero of the Great Prophecy to possess, possibly because it means he would "sacrifice the world" to save someone he really cares about. Athena also mentions that flaws that have a good motive are usually the most dangerous ones. They are often the same for demigod children of the same godly origin.

Siren's Music

The Siren's music has an oral hypnotic effect. When the Sirens sing, they sometimes reveal your fatal flaw. Flaws can produce an enticing image which is what lure sailors and adventurers to their deaths, either by drowning, being eaten by the Sirens, or by hitting the sharp rocks (and in modern times, mines) surrounding the island. When Annabeth and Percy are passing by their island, she asks him to tie her to the mast so she can hear the song but not escape to her death. However, after hearing the song, she manages to cut herself free with her knife and dives overboard because of the Siren's hypnotic song. When Percy goes to save her, he sees her vision. She thinks she can fix Luke Castellan, bring her mother and father back together again, and designed a brand new Manhattan. This is due to her fatal flaw, hubris or deadly pride.


Percy Jackson, whose fatal flaw, which is personal loyalty, affects the Great Prophecy.

Known Fatal Flaws

  • Percy Jackson: His fatal flaw is excessive/personal loyalty. He will risk his life for anyone: his friends, family, strangers, and sometimes even his enemies (like when he warned enemy demigods the Princess Andromeda was about to explode).
  • Annabeth Chase: Her fatal flaw is hubris, deadly pride. She thinks she can do anything better than everyone, even the gods, such as saving her family and build a brand new world exactly as she wanted (seen in The Sea of Monsters when she heard the Siren's music). Annabeth also says that many children of Athena share the same fatal flaw. In addition, her other fatal flaws are ambition. She desires power even though she knows she does not need it.
  • Nico di Angelo: His fatal flaw is holding grudges. He will hold a grudge even if it costs him his own life. In The Battle of the Labyrinth, his deceased sister, Bianca di Angelo, tells him that holding grudges is very dangerous for children of Hades.
  • Thalia Grace: Her fatal flaw is ambition. She desires power even though she knows she does not need it. She almost joined Kronos's army because of this in The Titan's Curse.
  • Leo Valdez: His fatal flaw is a feeling of inferiority. He always feels like he's the least important; even in the team of seven demigods, he feels that he is the "seventh wheel." 
  • Drew Tanaka: Her fatal flaw is vanity, or excessive pride in one's appearance, qualities, abilities, and achievements. She shares this flaw among many other children of Aphrodite.
  • Arachne: Her fatal flaw is hubris, deadly pride. She thinks she can do anything (weaving, in her case) better than everyone else, even the gods. This resulted in Athena turning her into a monster spider.
  • Pandora: Her fatal flaw was curiosity. When she was given the pithos from the gods, her curiosity made her open the pithos, which she was ordered not to do, causing the world's destruction.
  • Michael Varus: His fatal flaws are ambition and hubris. He showed ambition when he chose to journey to Alaska to solve the Prophecy of Seven, and he demonstrated the latter when ignoring the current augur's advice that the prophecy was not for him.
  • Odysseus: His fatal flaw was hubris. This was shown by his encounter with Polyphemus, when declared his true name after escaping the island, and by the statement that he won the Trojan War by himself, without any help from a god. Both of these brought the wrath of Poseidon upon him.
  • Perseus: His fatal flaw is anxiety. This was shown when he wanted to prove himself worthy of hospitality. He ended up promising that he would kill Medusa because of this, which gave rise to his near-impossible quest.
  • Hazel Levesque: Her fatal flaw was her past. This is shown by her flashbacks, and even though she ended up losing them, she still remembers her first life and treats it like her new life. For example, she treats Leo as if he were Sammy.
  • Luke Castellan: His fatal flaw was his excessive wrath. He was unable to forgive his father Hermes for what he had been through. Luke's anger blinded him so much that he went against his closest friends. By the time he realized it, it was too late and Luke ended up sacrificing himself.
  • Frank Zhang: His fatal flaw was his low self-esteem. In Son of Neptune, he showed doubts of his own self-worth, which caused him to panic at the time he is needed. However, after the Blessing of Mars, these flaws seem to have faded a little bit.
  • Phaethon: His fatal flaw was his recklessness. As a result of being raised by his over-protective mother and sisters, he starts to carelessly get himself in trouble. This flaw caused him to ride the chariot, ignoring the advice, and leading to his own death.
  • Jason Grace: His fatal flaw is his temptation to deliberate. For years in Camp Jupiter, Jason always relied on careful choices, compromises, and hearing both sides of a debate. He never chose what he wanted. He never knew where he wanted to belong. Notus said that Jason reminds him of his own children, blown place to place, undecided, change day to day. Notus warned him that such hesitation could kill him.
  • Piper McLean: Her fatal flaw is her low self-esteem. Being a daughter of a seemingly 'useless' love goddess, Aphrodite, she thinks herself as useless and invaluable. She feels so poorly of herself, which causes her getting constantly bullied by kids from Wilderness School. But these flaws seem to have reduced after House of Hades.
  • Hercules: His fatal flaw was his wrath. This flaw has led him to kill his own family, which caused him to the Twelve Labors. After that, he pushed an innocent boy off a cliff, causing him to work for the queen.
  • Theseus: His fatal flaw is impulsiveness/recklessness. He dumped Ariadne and rashly acted along with his brother Pirithous. He had the audacity to affront Hades, for which he was punished. Later, he fell out of favor from his subjects and died.
  • Bellerophon: His fatal flaw was hubris. He was too proud and attempted to force his way into Olympus. Zeus crippled him and the hero died slowly.
  • Thomas Jefferson Jr.: T.J., like all children of Tyr, has an instinctive inability to resist a challenge. This has lead to his death during the American Civil War and being baited into stabbing a stone giant in the heart.
  • Otrera: Her fatal flaw was hubris. She was too proud and fought Dionysus, almost getting herself killed in the process.
  • Psyche: Her fatal flaw was low self-esteem. She didn't trust herself to make the right decisions and was tricked by her sister to look upon Eros' true form.


  • It is stated by Athena that the most dangerous flaws are those that are good in moderation. In Percy's case, it is good to be loyal to your friends, but being overly loyal could lead to sacrificing Olympus or make you predictable to your enemies.
  • Of all the known Fatal Flaws, hubris is seen to be the most common throughout the series.
  • Hamartia is another word for a fatal flaw used mainly in the context of literature in reference to characters.
  • Thomas Jefferson Jr. is the only known Norse demigod whose fatal flaw is known.
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