Nemesis

"I enjoy tearing down the proud and powerful, and there are none who deserve tearing down like Gaea and her giants. Still, I must warn you that I will not suffer undeserved success. Good luck is a sham. The wheel of fortune is a Ponzi scheme. True success requires sacrifice."

- Nemesis to Leo and Hazel

Nemesis is the Greek goddess of balance, justice, retribution, and vengeance. Her Roman counterpart is also called Nemesis for revenge does not change from Greek to Roman myths, as revenge is universal, though she may also be equated with Invidia.

History
Nemesis is the daughter of Nyx and Erebus, however in some myths she is the daughter of Nyx alone. There were also some myths considering her to be a daughter of Dike, Zeus, or Oceanus and Tethys. She appears chiefly as the avenger of crime and the punisher of hubris, being mainly the goddess of revenge and justice.

The Battle of the Labyrinth
Although she was not seen in the series, she is the mother of Ethan Nakamura. Ethan tells Percy Jackson who his mother was right before swearing allegiance to Kronos and supplying the last piece to revive him. He tells Percy that he lost his eye shortly after learning who his mother was, saying that he found out what the meaning of the proverb, "An eye for an eye" the hard way. Later, Dionysus mentions that several of the minor gods are joining the Titans during the Second Olympian War, including Nemesis.

The Last Olympian
While Ethan joins Prometheus in a peaceful talk with Percy Jackson, he claims that he and his mother are not respected. Percy calls Nemesis the goddess of revenge and wonders why she deserves respect, but Ethan tells him that she is also the goddess of balance as she causes the downfall of people with too much good luck. He also tells Percy that Nemesis took his eye as payment for he would one day bring respect to the minor gods. While Ethan saw an eye as a small price to pay, Percy does not see Nemesis as a loving mother for taking her child's eye.

Later, as Kronos starts to destroy the thrones of the gods in Olympus, Percy reminds Ethan that his mother was the goddess of balance and that total destruction is not balance. This convinces Ethan to turn away from Kronos, but he is eventually killed when Kronos tosses him off Olympus. However, just like Nemesis promised, Ethan was able to bring respect to the minor gods by giving Percy the inspiration to ask for this change instead. Nemesis is one of the gods to receive a cabin, but it is unknown if she has any more demigod children.

The Mark of Athena
Nemesis appears in The Mark of Athena on the same island as Narcissus, Echo, and Narcissus's fan club. Leo and Hazel find her opening fortune cookies and changing the fortunes from optimistic to pessimistic (although she does leave alone the fortunes which she believes are enough). Leo initially perceives her as his Aunt Rosa, while Hazel sees her as her former teacher, Mrs.Leer; each is someone the demigod in question hated. Nemesis reveals that, after Leo bombed New Rome with the Argo II, the gods of Olympus blamed Hera for the budding civil war between the demigods, causing the goddess to flee from Olympus. Nemesis states that because of this, they can expect no help from Hera, and instead, offers her aid to Leo and Hazel, as she considers it her duty to tear down the proud and powerful, and she counts Gaea and the giants as the worst of that category.

Nemesis tells Hazel that she must save Nico by July 1 at the latest, and informs Leo that he will soon face a problem he can not solve. Nemesis offers him her help, though she warns that it will come with a painful cost. She gives Leo a fortune cookie, stating that when he opens it, he will have the answer to his problem. With that, she sends the two demigods off to find Narcissus and Echo.

Later, in Rome, Leo finally breaks open his fortune cookie to find the code to unlocking an Archimedes Sphere (though Nemesis is apparently irritated that he used the cookie to find a code). Though he successfully activates the sphere and saves Frank and Hazel from the eidolons, Leo is wracked with guilt shortly after when Percy and Annabeth fall into Tartarus, believing that the loss of the two demigods was the price he had to pay for rescuing his two companions earlier. He then keeps Nemesis' word, telling her he will defeat Gaea and the giants as the rest of the Seven and Nico di Angelo set sail for the House of Hades.

Personality
"Nemesis always pays her debts, good or evil."

- Ethan

Nemesis is seen as a cold and even cruel goddess whose ruthlessness is not exempt from even her own children as shown when she took her son's eye as part of their deal. However, Nemesis does have a strong sense of honor as exemplified when she swore to her son that he would gain recognition from this same agreement. Overall, she appears to be both fair and intense.

Appearance
Nemesis has short, curly black hair. She wears a red jacket, black jeans, black boots, and carries a whip as well as owning a motorcycle. Much like Aphrodite, who appears as someone the viewer loves, Nemesis will appear as someone you want to take your revenge on. This means that she will always look different to different people. Even if the observer sees this person, Nemesis' clothes do not change and Nemesis herself does not seem to know who she is perceived as.

Abilities

 * She has the standard powers of a goddess.
 * As the goddess of balance, she will provide bad luck to anyone with too much good luck. She may also be able to provide good luck to anyone with too much bad luck.
 * She can apparently tell someone their destiny as long as she receives adequate payment in return, as she told Ethan he would bring the minor gods respect in exchange for his eye.
 * She is able to punish those with too much arrogance, such as punishing Narcissus to fall in love with himself.

Known Children

 * Ethan Nakamura (deceased)

Trivia

 * The word "nemesis" is now often used as a term to describe one's worst enemy, normally someone or something that is the exact opposite of oneself but is also somehow similar.
 * Nemesis is also called the goddess of balance, she makes sure no man has too much good in his life to prevent hubris.
 * Ironically, Grover mentions in The Lightning Thief that Nemesis as the "God of Revenge" may be a possibility for Percy's parentage instead of one of the Big Three.
 * In The Last Olympian, Nemesis's symbol is a set of scales, as seen on Ethan Nakamura's burial shroud. In The Mark of Athena, Leo says a broken wheel is also her symbol, as it is on her cabin at Camp Half-Blood.
 * On Rick Riordan's website, Nemesis is said to be sisters with the Roman form of Tyche, Fortuna. Whether this is true only for the series or if Rick Riordan made a mistake is unknown.
 * It is odd that Ethan's burial shroud had scales under crossed swords when Nemesis is sometimes pictured with a whip in one hand and scales in the other.
 * The woman depicted on the New York state flag, holding the scales and sword, is believed to be based on Nemesis. However it is Dike the goddess of Moral Justice, or in some cases Dike's mother Themis.
 * A statue of Nemesis or Dike's mother, Themis, is sometimes seen in courts of law to represent balance of justice.
 * Despite Invidia being Nemesis' Roman form, she herself states that she is called Nemesis in both Rome and Greece as revenge is universal.
 * Her Roman name, Invidia, is Latin for Envy, one of the seven deadly sins.