The Heroes of Olympus
The logo for the The Heroes of Olympus series
|Genre||Fantasy, Young-Adult fiction, Mystery, Greek and Roman mythology, Romance|
|Media type||Print (hardback and paperback)
|Preceded by||Percy Jackson & the Olympians|
The Heroes of Olympus is a pentalogy of young adult fiction novels by Rick Riordan which collectively form a sequel to Percy Jackson & the Olympians. The final entry in the series, The Blood of Olympus, was published on October 7, 2014.
The Heroes of Olympus is centered around a prophecy, introduced in The Last Olympian (last book in the Percy Jackson & the Olympians book series), that predicted seven demigods would unite to protect the earth from Gaea, who plans to destroy it.
The Lost Hero
The Lost Hero, the first book in the Heroes of Olympus series, was released on October 12, 2010.
Jason Grace has no memory of his identity or how he came to be on the bus with a group taking a field trip to the Grand Canyon. Leo Valdez claims to be his best friend and Piper McLean, his girlfriend. At the Grand Canyon, one of the students reveals himself to be a Greek monster, and a horde of Venti attacks the three and their supervising teacher, Coach Gleeson Hedge, who reveals himself to be a Satyr and confronts the Venti. Jason is able to defeat the Venti's helpers, but the Venti capture Coach Hedge and flee. Two strangers arrive in a flying chariot: Annabeth Chase (daughter of Athena) and Butch (son of Iris). Annabeth is hostile towards Jason when they meet as she had been told that to find Percy she must find the guy with one shoe. Jason is only wearing one shoe, yet Percy is not there, which causes her distress.
Jason, Piper, and Leo are taken to Camp Half Blood and are informed that they are demigods, children of the ancient Greek gods. Jason seems to prefer the gods' Roman forms instead of Greek. Leo is immediately claimed by Hephaestus, a glowing red hammer appearing above his head as soon as he reaches Camp Half Blood. At the campfire that night, Piper is given the blessing of Aphrodite, revealing her to be a daughter of Aphrodite. Piper quickly forms a rivalry with Drew, the bossy senior counselor of her cabin. Jason is revealed to be a son of Zeus after he summons his power to call lightning. He is also revealed to be the brother of Thalia, a main character from the Percy Jackson series. Jason remembers Thalia when he sees a picture of her in Zeus's cabin and learns that Hera/Juno has stolen his memories. Piper is jealous of Thalia at first, until she realizes that Thalia is Jason's biological sister. Annabeth takes Jason to see Clovis, a son of Hypnos (god of sleep) to try to find some of his memories through sleep. Clovis explains to him the difference between the gods' Greek and Roman forms.
Less than a day later, the three new demigods are sent on an urgent quest to rescue Hera, who has been kidnapped by a giant. The three set off on the back of a giant robotic dragon, Festus (which in Latin, means "happy") that Leo finds and repairs. They first travel to Quebec, Canada, where they meet the god of the North Wind, Boreas. Piper discovers that she can speak French, as she speaks with the god and his sons and daughter, Khione. They travel back south, where Festus crashes mysteriously, leaving the three demigods to explore an abandoned tire factory. While Leo goes to find Festus, Jason stays inside the factory with Piper, who has broken her ankle. She heals herself with ambrosia and nectar, the food of the gods, while Jason sets out to explore. When he doesn't return, Piper become suspicious and is captured with Jason by the three Cyclops who have taken up residence in the ancient building. Leo sneaks inside and crushes the cyclops with a crane, releasing Piper and Jason,who has been knocked unconscious. Leo repairs Festus, and when everyone is back in good health, they set off again. Seeking a place to sleep, Leo finds a sewer to set up camp in. The demigods then discover a weird shop, which turns out to be owned by the evil sorcerous Medea, who tries to kill them with poison. They escape after a fight, leaving Medea in her burning building. Festus crashes again, this time attempting to land on someone's property. Everything is thrown into confusion when a large flash of light sends everything tumbling down. The property turns out to be protected by a laser system, which slashes Festus into pieces, damaged beyond repair. The demigods tentatively enter the house and find Coach Hedge frozen in place in a cage. They fall asleep, and wake up to a man discovering them passed out on the floor. The entire house turns out to be made gold, a detail they missed as it was dark when they entered. The man is discovered to be King Midas,who manages to turn both Leo and Piper to gold before Jason finally manages to kill him by blasting the house with lightning. It begins to rain, returning everyone, including Coach Hedge, to normal. Later in the journey, the demigods are attacked by King Lycaon and his pack of Werewolves, when they are suddenly rescued by the Hunters of Artemis. Jason and Thalia are reunited, and the two groups set out to seek help from Aeolus, the god of all wind. He is driven a bit crazy from managing all of the gods' requests for weather in different regions, and is proven to be quite dangerous after he sends a flock of angry harpies after the demigods and Coach Hedge. Luckily, they are rescued by Mellie, a helpful wind spirit whom Hedge falls in love with. They discover that Hera's kidnappers are Gaea's underlings and that she seeks to overthrow the Olympians.
They save Piper's father (Tristan McLean, a movie star), whom Enceladus has held ransom, and release Hera from her prison. They temporarily stall Gaea's plans, but the newly risen Porphyrion is able to escape. After the battle, they return to camp, where Leo starts building the Argo II, the flying ship for their next mission. Festus' mechanical, fully functioning head is featured as the masthead of the Argo II. Piper also overthrows Drew as senior counselor and gains new-found self-confidence. After part of his memory returns, Jason realizes that he is from the Roman counterpart to Camp Half-Blood called Camp Jupiter. He remembers a girl named Reyna and that Hera switched his place with Percy Jackson, who is now at Camp Jupiter with no memory of his life at Camp Half-Blood.
The Son of Neptune
The Son of Neptune, the second book in the Heroes of Olympus series, was released on October 4, 2011.
The Son of Neptune opens with Percy Jackson being chased by two gorgons, Stheno and Euryale, who seek revenge for killing their sister Medusa (The Lightning Thief). Percy has lost all memory of his past. They reveal that they're working for Gaea. While making his escape, Percy runs into an old woman named June, who gives him a choice: do her a favor or live safely under the sea while everybody and everything is destroyed. He meets Hazel Levesque, a daughter of Pluto, and Frank Zhang, who is later revealed to be a son of Mars. Hazel and Frank are guarding Camp Jupiter, but let Percy in, as Hazel believes it could be a test from the gods. As the favor, Percy carries June across the Little Tiber, which is a powerful river. In the process, he loses his invincibility from the River Styx. When he reaches his destination, Percy saves Frank from the Gorgons by drowning them. Quickly after, June reveals herself to be the roman goddess Juno (Hera). She brings a message of warning: "... Death must be unleashed if you are to stand any hope in the battle.".
Percy is taken into the camp after Juno introduces him to Camp Jupiter. Reyna seems to recognize him, but refuses to acknowledge him. It is revealed in "The Son of Neptune" that she and her sister lost their home during Percy's attack (in Percy Jackson and the Sea of Monsters). She sends Percy and Hazel to Octavian, the camp augur, to determine whether or not he's fit to join the legion. Along the way, Lares, the camp's ancestral spirits, call him Graceus, or "Greek," which worries Hazel. When they reach Jupiter's temple, Octavian is slicing teddy bears open and reading the stuffing. Octavian threatens Hazel by telling her that if she doesn't vote for him, he'll reveal her secret. He declares good omens, and Hazel and Percy go to the temples, where they meet Nico di Angelo, a main character from the Percy Jackson series. He knows Percy, but claims he does not recognize him. Meanwhile, Frank is organizing weaponry when a Lare appears and tells him he knows about his stick and his birth. Frank runs off to find Hazel and Percy. He takes Percy to the baths while Hazel and Nico talk. Hazel reveals that she's from the 1940s and has a blackout during which she relives scenes from her past and moves around in a spirit-like form. She realizes that she's late for the role call, so she and Nico rush to line up. Percy is accepted into the Fifth Cohort, the least popular of all cohorts.
During war games, a Camp Jupiter activity, Percy impresses everyone with his battle skills and instincts, even though they are not Roman tactics and are more Greek-style. After the games, Octavian deliberately hurts Gwendolyn (Gwen), a centurion from the Fifth Cohort. She is severely injured and dies, only to come back to life a few moments later. Mars, the god of war, appears and informs the campers that "death has been chained" and claims Frank Zhang as his son. Mars insists that Percy and Frank must go on a quest to free Thanatos, the god of death. He has been captured in Alaska and is no longer able to keep mortals dead. Frank requests that Hazel accompany him on the quest, and they set off towards Alaska.
While traveling on their quest, Percy struggles to regain his memory. Time and time again, he recalls things but is never able to determine from where. His only clear memory is of a girl named Annabeth. Hazel reveals that she died long ago, but her half-brother Nico Di Angelo, son of Hades, saved her from the Underworld. Frank tells the other two that he was given a piece of wood that is tied to his life. If the wood burns completely, he will die. After they experience many events and monsters (including basilisks, giants, and an unexpected meeting with the Amazons, in which Hazel gets a magic super-fast horse named Arion), they meet Reyna's sister, who helps them and gives Hazel a powerful horse named Arion, who only eats gold and is a son of Neptune. They finally arrive in Alaska, where they find Thanatos in chains, which can only be broken by the fire of life (referring to the piece of wood tied to Frank's life). Percy defends Frank while he melts Thanatos' chains with his burning stick, losing more and more of his life. Hazel attacks Alcyoneus, the giant born to oppose Pluto. Thanatos is eventually freed and with the help of Hazel's horse, Arion, and they drag the giant out of its land of Alaska to Canada where it is able to be killed.
Percy regains his memory as they race back to Camp Jupiter. Knowing that the camp is under attack, Percy takes charge and leads the Romans into battle with the help of some of his old friends from Camp Half-Blood and the Amazons. The morale of the Romans is recharged after they discover that Percy recovered the camp's lost standard, which had been missing for years. Percy challenges the giant, Polybotes (the giant born to oppose Neptune), to a duel and calls to Terminus, the Roman border god, to help him defeat the giant. Percy has been told that only when gods and demigods work together can the giants be defeated. He defeats Polybotes by using the head of Terminus' statue as a weapon. The camp names him a praetor, a leader of the Roman camp. The Greek demigods from Camp Half-Blood appear in the flying ship Argo II sailing towards the camp. The Romans argue over attacking the ship. As praetor, Percy orders them to hold their fire. If the Greeks attack, he would be to blame, but he is not worried. With his arms around Frank and Hazel, he approaches his "other family".
The Mark of Athena
The Mark of Athena, the third book in the Heroes of Olympus series, was released on October 2, 2012.
After sending Leo's video to Camp Jupiter, Argo II prepares to land on the Roman camp's border, but Terminus, the god of borders, stops them, for no weapons are allowed inside. It is then decided to let the ship stay in the air while Annabeth, Leo, Piper, and Jason meet the Roman campers. Percy Jackson, together with Hazel and Frank, welcomes the Greek demigods and Coach Hedge. They hold a reunion and, during the conversations, Ella, the harpy, speaks about a prophecy that refers to Annabeth's quest for the Mark of Athena. Piper uses her charmspeak in order to divert the topic. While Jason gives Piper a tour of the camp, Reyna talks to Annabeth alone.
During their conversation, the Argo II, which is controlled by Leo Valdez (who was possessed by Eidolons), fires at Camp Jupiter. The Romans defend their bases, and Annabeth, Piper, Jason, and Percy rush inside the Argo II to stop Leo from firing on the camp. They start to leave the camp, while Hazel and Frank delay the Roman campers. The Argo II becomes damaged and, when Leo lands for repairs, they encounter Echo and Narcissus. They are told that they have to search for the Mark of Athena to bring the Romans and the Greeks together.
During their journey, they meet Phorcys and Keto. The seven quickly leave for Charleston. Annabeth, Piper, and Hazel go to Battery Park to find a mysterious ghost, which happens to be Aphrodite. Jason, Leo, and Frank go to a museum in Fort Sumter. Only the girls' story is told. Aphrodite tells them about their love lives and the other Olympians that are suffering from confusion about their Roman or Greek identities. After their talk, the angry Romans arrive, and war breaks out. Annabeth meets Reyna, who is in Fort Sumter to retrieve a map which will save her friends. Reyna begs Annabeth to come with her and die a painful death to save her camp, but Annabeth tells Reyna that she will only follow the mark.
The seven reach the ship and leave safely to go to Chiron's brothers, who live in the sea. During the ride, they are attacked by a shrimp monster. Leo, Frank, and Hazel go underwater and find icthyocentaurs, Chiron's brothers, who find the three's story interesting and speed their way to Rome. They meet Hercules near the pillars, at the entrance to Rome, and Piper and Jason get the second horn of Achelous, the bull-headed river god. Even though it was Hercules who ordered them to cut it off, Piper decides that Hercules does not deserve the horn and keeps it for herself. She brings forth a pile of food, and Hercules falls.
The seven cross the pillars and sail into Rome. Annabeth has to find the Athena Parthenos by following the Mark of Athena and battle its guardian Arachne. Percy, Jason, and Piper travel into an underground area and battle the twin giants, Otis and Ephialtes, the anti-Dionysus. Frank, Hazel, and Leo travel in search of Nico, and find Archimedes' scrolls on spheres. In the end, Annabeth outwits Arachne by tricking her into weaving her own trap. Percy and Jason battle the giants and, with very little (emphasis on "very little") help from Dionysus's Roman counterpart, Bacchus, they rescue Nico, and Bacchus defeats Otis and Ephialtes by throwing a pinecone into their eye.
Frank, Hazel, and Leo battle the Eidolons and rescue Archimedes' scrolls and one of his spheres. They meet, and Annabeth secures the Athena Parthenos. However, Arachne pulls Annabeth into Tartarus by some spider silk tied to Annabeth's ankle as the statue is lifted onto their ship. Percy grabs Annabeth's hand but is pulled in as well. After Percy and Annabeth fall into Tartarus, the remaining five prophecy demigods, Coach Hedge, and Nico conduct a meeting. Nico says Percy told him to lead the demigods to the Doors of Death, and he and Annabeth would meet them at the end of Tartarus on the Doors' other side. Nico and Hazel both say they are fairly sure Percy and Annabeth are not dead yet. The book closes with Leo telling Festus the Dragon figurehead to set sail so they can save their friends.
The House of Hades
The House of Hades, the fourth book in the Heroes of Olympus series, was released on October 8, 2013.
Percy and Annabeth are falling towards Tartarus. Shortly after arriving in Tartarus, Annabeth and Percy find the River of Fire, The Phlegethon,and drink from it, which makes them immune to the harsh Tartarus environment, albeit temporarily. Annabeth and Percy follow some Empousai, including Kelli (originally seen in Battle of the Labyrinth), to try and find the Doors of Death. Percy and Annabeth eventually are spotted and almost killed, until Bob, the Titan (the name to which Percy changed Iapetus's name in The Demigod Files: The Sword of Hades when he dragged Iapetus—a Titan—through the River Lethe) comes and helps vanquish them. Bob leads them to The Shrine of Hermes, where Annabeth successfully sends a message back to Camp Half-Blood. Bob joins them on their journey to the heart of Tartarus.
Annabeth and Percy meet Nyx (Night) in Tartarus. Annabeth devises a plan to trick Nyx and her children into blinding each other with darkness, giving Annabeth and Percy time to flee into the Mansion of Night, where they meet up with Bob at the Doors of Death. Annabeth, Percy, Bob and Small Bob (Bob's new-found pet cat, a flickering skeleton of a saber-tooth tiger, first seen in The Titan's Curse at the Museum of Natural History) then head directly towards the Doors of Death. As the group trudges amidst the colossal number of monsters, they encounter Hyperion and Krios, who are guarding the Doors of Death. Just as they are about to cut the chains securing the Doors, Tartarus appears in person, destroys the Titans, and removes the Death Mist from Percy and Annabeth. Percy is traumatised and loses all will to fight, while Annabeth is void of ideas. Bob challenges Tartarus and, just when he begins to lose the battle, Damasen charges into the battle with his drakon, declaring that he has decided to choose his own fate. With Damasen holding off Tartarus and Bob securing the Doors of Death, Percy and Annabeth finally escape Tartarus, but not before Bob says, "Tell the sun and stars hello for me"
In the mortal world, the crew is joined by Reyna, who has made it to the ship, losing her pegasus Scipio in the process. While discussing their next course of action, the crew decides that the Athena Parthenos must be transported to Camp Half-Blood, and they must head towards Athens to face the giants. With only two weeks left before the revival of Gaea at the Feast of Spes, the crew is unable to decide where to go. After much debate, Nico volunteers to shadow-travel with Reyna and Coach Hedge back to Camp Half-Blood, while the crew can head towards Greece. The book concludes with Percy saying to the stars, "Bob says hello."
The Blood of Olympus
The Blood of Olympus, the fifth and final book in the Heroes of Olympus series, was released on October 7, 2014.
The seven united Greek and Roman demigods of the Argo II crew journey to Athens in a final attempt to prevent Gaea from awakening and destroying the earth, while Reyna, Nico, and Coach Hedge travel with the Athena Parthenos in tow to Camp Half-Blood, hoping to prevent war between the massed groups of Greek and Roman demigods, and to unite the groups. Gaea will rise if two of the seven on the quest are sacrificed to her during the Feast of Spes, and her children, the powerful, already risen giants, can only be defeated by demigods and gods working together. With the Greek and Roman aspects of the gods warring within themselves, the gods are incapacitated, yet the questing demigods must somehow save the planet and all who live on it from the earth mother herself. The Blood of Olympus will fulfill the following lines of the prophecy: 'To storm or fire the world must fall. An oath to keep with a final breath...' The House of Hades gives a possible hint to the meaning of the third line of the prophecy (an oath to keep with a final breath).
The Demigod Diaries
Released August 14, 2012, The Demigod Diaries is a collection of short stories. Similar to The Demigod Files, it contains some new stories with character interviews, illustrations, puzzles, and a quiz. The four stories include:
- "The Diary of Luke Castellan": Thalia and Luke meet Annabeth in Richmond, Virginia, after a disturbing encounter with a cursed, reclusive son of Apollo, before the Percy Jackson & the Olympians series.
- "Percy Jackson and the Staff of Hermes": Percy and Annabeth are sent by Hermes to retrieve his caduceus from the fire-breathing giant Cacus.
- "Leo Valdez and the Quest for Buford": Jason, Leo, and Piper confront crazed Maenads while searching for Buford the table, which has absconded in a fit of pique, at Camp Half-Blood between The Lost Hero and The Son of Neptune.
- "Son of Magic": Alabaster Torrington, a demigod son of Hecate who fought on Kronos's side, finds himself in a fight to the death with Lamia after being banished from Camp Half-Blood following Kronos's defeat in the Second Titan War in The Last Olympian and seeks the help of a well-known expert on death. This story was written by Rick Riordan's son Haley Riordan.
- Perseus "Percy" Jackson: The 17-year-old son of Poseidon (Roman form: Neptune), Percy was the narrator and main protagonist of the preceding series Percy Jackson & the Olympians. As a child of one of the "Big Three" gods, Percy is one of the most powerful living half bloods. He possesses the power to control water and has perfect bearings at sea. He can also breathe underwater and communicate with all creatures of the sea and horses, Pegasi included. He carries a sword called "Riptide" (Ancient Greek:[Anakulusmos] Ανακλυσμός). A major part of both the first Great Prophecy and the Prophecy of Seven, Percy fought Kronos and the other villainous Titans with the help of his friends, and became the star of Camp Half Blood. He is offered the chance to receive immortality but declines wanting to finish his high school education (and also for Annabeth). In Heroes of Olympus Percy's memories are stolen by Hera, who sends him to replace Jason Grace at Camp Jupiter. There, he quests alongside demigods Hazel and Frank to rescue Thanatos and destroy the immortal giant Alcyoneus. In gratitude for his successful venture, Percy is made a Praetor at Camp Jupiter, and later reunites with his Camp Half Blood friends to sail in the Argo II to Rome. Percy is in a relationship with Annabeth Chase, daughter of Athena since the last book in the Percy Jackson series, The Last Olympian.
- Leo Valdez: A 15-year-old Greek demigod, he is the son of Hephaestus. He possesses the power over fire, a rare ability, even among the children of Hephaestus. He created the Argo II, using his skills with fire and machinery. He is part of the Second Great Prophecy and is a descendant of Sammy Valdez, Hazel's old boyfriend. He has a crush on Calypso. He swore on the River Styx that he will come back to her. Leo has a special connection to Gaea, who appeared to him as a child, and caused his mother's death. Many of the foes they face refer to him as "The Seventh Wheel" due to the fact he doesn't seem to fit in with the others - a topic he is aware of. He appears carefree and wisecracking, but, is shown to be quite insecure about his place among the others.
- Piper McLean: A 15-year-old Greek demigod, she is a daughter of Aphrodite (Roman form:Venus). She can charmspeak (convince or persuade most people to do what she says). She carries a knife called Katropris, which used to belong to Helen of Troy, and shows her visions of the future. Although she is a tomboy and tries to playdown her beauty, she is very beautiful. She is part of the Second Great Prophecy and the senior counselor of the Aphrodite cabin. She is dating Jason Grace, son of Jupiter, though she fears he may be taken from her by Reyna, his close Roman friend.
- Annabeth Chase: A 17-year-old daughter of Athena, she is highly intelligent, wise, and always ready with a plan, a back-up plan and the back-up of the back-up plan. After the war against Kronos, the Olympians crowned her "Head Architect of Olympus," as Kronos destroyed part of Olympus during the battle. Annabeth is known to be part of the Second Great Prophecy and, to this effect, leads the Argo II to Camp Jupiter. She has been the girlfriend of Percy Jackson, son of Poseidon, since The Last Olympian. Annabeth wants to bring peace by following the Mark of Athena and finding the stolen statue (Athena Parthenos), dedicated to her mother. She doesn't completely trust Jason Grace at first, but eventually comes to common terms with him, as she is best friends with his sister Thalia. She is one of the smartest demigods, and is able to outwit Arachne in order to save the Athena Parthenos. When Annabeth was seven years old, she ran away from her home, only to face monsters and eventually meet Thalia and Luke, two demigods traveling to camp half-blood. The three bonded strongly, and Luke's passing, along with Thalia being temporarily changed into an evergreen pine tree, affected her greatly. She had a crush on Luke Castellan for some time but now is with Percy. Her birthday is on July 12 around 1993.
- Nico di Angelo: 14 year-old Greek demigod, he is the only known son of Hades and the younger brother of the late Bianca di Angelo. Although he was born in Venice, Italy, in 1927, he is physically and developmentally 14. He and his sister were brought to the United States as young children by their mother, the daughter of an Italian diplomat. He still speaks Italian fluently. His mother was killed by Zeus, who was attempting to kill Bianca and Nico before they turned 16 because of the Great Prophecy (later fulfilled by Percy and Luke Castellan). Bianca and Nico spent the next 70 years in the Lotus Hotel before Hades had Alecto took them out and put them in a military school in Bar Harbor, Maine, hoping to have them fulfill the Great Prophecy. Nico's Roman half-sister is Hazel Levesque, a daughter of Hades' Roman counterpart Pluto, and is from Camp Jupiter. He has the power of necromancy and is one of the most powerful demigods currently living. In The Titan's Curse, he develops a grudge against Percy, thinking he purposely killed Bianca. Nico believes Percy was trying to kill him with some skeletons that followed him. In The Battle of the Labyrinth he learns to trust and not to hold grudges (the fatal flaw of most children of Hades) against people. He is the only demigod prior to the Heroes of Olympus series to have attended both Camp Half-Blood and Camp Jupiter, and was the first Greek to know about Camp Jupiter in The Son of Neptune. Nico briefly visits Camp Jupiter in The Son of Neptune, but pretends to not know Percy. After his visit, he attempts to locate and close the Doors of Death. In the process, he is pulled into Tartarus and nearly dies, which allows Gaea's forces to overwhelm him. He is briefly imprisoned in Epirus, before being transported to Rome by Ephialtes and Otis, who attempt to use him as bait for the other campers. They rescue him, and he later promises Percy to lead the others to Epirus in Greece, while Annabeth and Percy locate the entrance to the Doors of Death in Tartarus. In The House of Hades, he reveals that he developed a crush on Percy as a child, and that this homosexual attraction and the stigma against it in the 1930s is what prompts his aloofness from both Greek and Roman camps.
- Gleeson Hedge- The protector of the 9 heroes of Olympus. He is 106 years old (53 in human years, though). He is described as warlike and scary, but is actually a softie when it comes to caring about people. According to Leo, he can be trigger happy. He also has a wife named Mellie who is a cloud Nymph.
- Thalia Grace: Chronologically 21, but physically and psychologically 15, Thalia is Jason's biological sister, but a daughter of Zeus rather than Jupiter. She was born on December 22 around 1988. Thalia was almost killed when she was 12 after being revealed to be a child of one of the "Big Three" gods (Zeus, Poseidon, and Hades), and made a final stand against a group of hell hounds and the Three Furies on Half-Blood Hill to protect her companions, Annabeth Chase and Luke Castellan (who turned against the Gods in The Lightning Thief). Zeus takes pity upon his daughter and transforms her into a pine tree. After Luke poisons the tree in The Sea of Monsters, Annabeth, Percy, and Clarisse La Rue find and use the Golden Fleece to save the dying pine. The magic works too well, and Thalia is separated from the tree as a human, albeit slightly younger physically than her age would have been if she had aged normally. She later joins the Hunters of Artemis just before her birthday, becoming immortal while developmentally still 15, thereby making sure to escape the Great Prophecy. During the Demigod Files, she went on a quest for Persephone with cousins Percy and Nico.
- Tyson: Tyson is a cyclops by nature and is also the half-brother of Percy by virtue of their father being Poseidon. In The Son of Neptune, Tyson, along with Percy's hell hound Mrs. O' Leary, is revealed to be searching for Percy. It appears that Tyson is the most successful at tracking Percy down and is nearly at Camp Jupiter before Percy leaves for his quest. He continues to track Percy and his friends north, but is always too late to reach them. Shortly after the attack on the Zhang mansion, Percy contacts him via a dream, telling him to locate the harpy Ella and escort her back to Camp Jupiter. Tyson, Ella and Mrs. O' Leary meet Percy just outside the camp, and it is implied that Tyson and Ella are in love with each other. Ella later chooses to follow Tyson rather than fly to safety, and Tyson aids the Romans in defeating the giant Polybotes' forces. In The House of Hades it is revealed that she and Tyson are now dating.
- Rachel Elizabeth Dare: Camp Half-Blood's oracle. Rachel is not a demigod or a legacy; she is a regular mortal human who was born with the gift to see through the Mist. This gift allows her to predict the future, but it is recommended not to touch her when she is having an episode. She has frizzy red hair and always has a blue plastic hairbrush in her front pocket, which she previously used to hit Kronos in the eye. Jason dreams about her and Grover having a "talk" with Reyna and Octavian. She helped Percy in Annabeth's quest in the Labyrinth. She can't be married or have a boyfriend while being the oracle.
- Grover Underwood: Percy's best friend, who is a satyr. He and Percy have an empathy link, and they need to be careful or if one of them dies, both of them die. He has some skills in woodland magic and carries around a pair of pipes, just in case. He has curly brown hair and brown eyes, and a furry hindquarters. He has a girlfriend, a dryad named Juniper, who cares for him very much.
- Jason Grace: A 16-year-old Roman son of Jupiter, he was born on July 1 (the Kalends of July, a day sacred to Hera). He can fly, control winds and lightning, and create storms. He is a natural leader and was praetor before Hera took his memory and sent him to Camp Half-Blood. He carries a sword as a weapon (given to him by Hera) as his first weapon, Ilvis, was destroyed. His sister is Thalia Grace, daughter of Zeus. He is dating Piper McLean and has confirmed in the series that he has no feelings for Reyna, although Piper is still dubious of it. He is portrayed as very handsome, with combed blond hair and electric-blue eyes, just like Thalia. He is part of the Prophecy of Seven.
- Hazel Levesque: A 13-year-old Roman demigod, she is a daughter of Pluto and a voodoo priestess named Marie Levesque. Hazel has the ability to control precious metals and gems, has perfect bearings underground and can open new passages and tunnels underground. Lumps of precious metal and gemstones pop out of the ground around her, but bear a curse to whoever picks them up, and she tries to prevent people from doing so. She is African-American and was born on December 17, 1928. She is originally from New Orleans but, on her 14th birthday in 1941, she moved to Alaska, where she died with her mother a few months later in 1942 while standing up to the earth goddess Gaea. Nico di Angelo, her half brother, finds her in the Underworld 70 years later while looking for his dead sister, Bianca. Nico, feeling that Hazel needs a second chance, brings her back to life. She was 13 when she died and, when she returns, she is still 13 physically. Hazel is a part of the Prophecy of Seven. She is dating Frank Zhang, though Leo Valdez looks eerily like a boy named Sammy Valdez (Leo's great-grandfather) whom she used to date in New Orleans during her first life. If she had not died, she would have married him.
- Frank Zhang: A 16-year-old Roman demigod with magical blood, he is a son of Mars and a descendant of Poseidon on his mother's side. He is descended from Periclymenus, son of Poseidon and Prince of Pylos. He is a Canadian from Vancouver, but has a vast ancestry coming from China, Rome, and Greece. His family's hometown is Li-Jien, or Legion. His last name, Zhang, means "master of bows." He possesses the power to shapeshift, an ability inherited from his ancestor Periclymenus. He is a part of the Prophecy of Seven. He is dating Hazel Levesque, daughter of Pluto. He is jealous of Leo because he believes Leo likes her, and Hazel has feelings for him because he's similar to Sammy. Frank's last hope for life relies on a piece of firewood (the Fire of Life, as it is called by Thanatos in The Son of Neptune) that holds him between life and death which he gives to Hazel Levesque to keep safe for him. This piece of wood is similar to Meleager's log.
- Reyna Avila Ramirez-Arellano: A 16-year-old Roman demigod and daughter of the Roman goddess of war, Bellona. She is one of the Roman praetors of Camp Jupiter. Percy Jackson says that she is a fighter. Her older sister is Hylla, Queen of the Amazons. Both Hylla and Reyna meet Percy Jackson in The Sea of Monsters. At first, they hate him for their encounter at Circe's island, but soon come to make amends. It is hinted that she dated Jason Grace, her first partner in praetorship, and has a crush on Percy Jackson, her previous partner in praetorship. She despises the camp's augur, Octavian. She has two metal dogs, Argentum and Aurum (Silver and Gold), both of which can tell when a person is lying. She is Puerto Rican, from San Juan, and hates to use her full name or have it be used by others, as she considers it a reminder of a painful childhood she has left behind.
- Octavian: An 18-year-old descendent of Apollo, he serves as the camp's augur. He is a very conniving politician who desired to succeed Jason Grace as praetor. Percy Jackson's arrival at Camp Jupiter, however, ruined his plans. Instead of actual animals, he slices up stuffed animals. He is described as pale and skinny, with stringy blonde hair. Manipulative and power-hungry, he is Reyna's strongest political rival. His great skill as an orator makes him very persuasive.
- "Heroes of Olympus". Rick Riordan. Archived from the original on October 18, 2014.
- "'The Blood of Olympus' by Rick Riordan hits shelves today!". Hypable.
- ""The Heroes Of Olympus: The Demigod Diaries" To Be Released This August". LeakyNews. 2012-01-01. Retrieved 2012-11-11.