Nemesis

Nemesis (Νέμεσις in Ancient Greek) is the Greek goddess of balance, justice, retribution, and vengeance. Her Roman counterpart is also called Nemesis.

History
Nemesis is the daughter of Nyx and Erebus, however in certain myths she is the daughter of Nyx alone. She appears chiefly as the avenger of crime and the punisher of hubris being mainly the goddess of revenge and justice. The rest comes from that.

The Battle of the Labyrinth
Although she was not seen in the series, she was mother to Ethan Nakamura. Ethan tells Percy Jackson who his mother was right before joining Kronos' side in the war and supplying the last piece to revive him. He tells Percy that he lost his eye shortly after learning who his mother was, saying he found out what the meaning of "An eye for an eye" was the hard way. Later, Dionysus mentioned that several of the minor gods were 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 him and his mother aren't respected. Percy calls Nemesis the god of revenge and wonders why that deserves respect, but Ethan tells him that she is instead the goddess of balance, bringing down people with too much good luck. He also told Percy that Nemesis took his eye as payment for one day bringing respect to the minor gods. While Ethan saw an eye as a small price to pay, Percy doesn't see Nemesis as being a good mother for taking her child's eye.

Later, as Kronos went to the top of Olympus to destroy the Thrones of the gods, Percy reminded Ethan that his mother was the goddess of balance and that total destruction isn't balance. This convinced Ethan to turn away from Kronos, but was eventually killed when Kronos tossed him off Olympus. However just like Nemesis promised, her son gave Percy the inspiration to wish for the gods to respect the minor gods more by giving them cabins at Camp Half-Blood and thrones on Olympus. Nemesis was one of the gods to receive a cabin, but it is unknown if she has any more demigod children.

The Mark of Athena
"True success requires sacrifice."

- Nemesis, to Leo and Hazel

Nemesis appears 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 leaves "You will have cause to reconsider your choices soon" alone). 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. She 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, then informs Leo that he will face a problem he can not solve. Nemesis offers him her help, though she warns that it will come only with 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 for the Archimedes Spear. Though he successfully activates the sphere and saves Frank and Hazel from the Eidolons, Leo is wracked with guilt shortly after when Percy Jackson and Annabeth Chase fall into Tartarus, believing that the loss of the two demigods was the price he had to pay for rescuing his two companions earlier.

Personality
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 seems to be both fair and intense.

Appearance
Nemesis has short, curly black hair. She wears a red jacket, black jeans, and black boots, along with carrying a whip. She owns a motorcycle. Much like Aphrodite however, Nemesis looks different depending on who is looking at her. She always appears as someone that the looker wants revenge on, Leo saw his Aunt Rosa and Hazel saw an old teacher. Even if people see the person they most want revenge on, Nemesis' clothes don't change and Nemesis herself seems to not know who others see her 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 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 inlove with himself.

Known Children

 * Ethan Nakamura (deceased)

Trivia

 * 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.
 * In The Last Olympian, Nemesis's symbol is a set of scales, as seen on Ethan's burial shroud. In The Mark of Athena, Leo says a broken wheel is also her symbol, as it is on her cabin (16) 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 to the series or if Rick Riordan made a mistake is unknown.
 * It's 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, because: "Revenge is universal."