|Augur of Camp Jupiter|
|Legacy of Apollo|
|Centurion of the First Cohort|
|Weapons||Ceremonial knife, dagger|
|Appearances|| The Son of Neptune |
The Mark of Athena
|“||I hope it hurt.||”|
Reyna tells Hazel that after she questions Percy, she will send him to Octavian who will consult the Auguries and decide what to do with him after conferring. Percy describes Octavian as a "teddy bear murderer."
The first time Octavian meets Percy is at the Temple of Jupiter Optimus Maximus. Percy quickly learns that he is blackmailing Hazel into voting for him in the upcoming election for the Praetor, as he found out about her raising Alcyoneus or being dead or both.
Later during the war games, he is suspected of killing Gwen by spearing her from behind possibly after the games were already over. Frank notes that Octavian was the only one without a pilum and was at Gwen's back when she was stabbed. Gwen returns from the dead, claiming that she saw a man who was asking for a coin, but she just left. Frank pulls the pilum out and the wound heals automatically.
Mars appears on the field a moment later to issue a quest, saying that his son, Frank, will lead it. He also orders that Percy is to go to learn some respect for Mars. Octavian claims that they need a prophecy and states that he will go fetch his stuffed animals for one. Mars simply writes down a prophecy. The prophecy is extremely blunt and Octavian protests, declaring that prophecies must be wrapped in riddles. When Mars pulls a grenade from his belt, Octavian quickly changes his tune and treats the order as an actual prophecy.
The second time he is seen is during the Senate meeting where he convinces the others into trying not to give Percy, Frank, and Hazel supplies on their trip, as that is the traditional Roman way. However, Reyna allows them to use the The Pax for their quest.
After the battle against the Giant Army, Percy is raised on a shield as the Roman campers chant "Praetor," electing Percy to the position, much to the irritation of Octavian. At the Feast of Fortuna, he gives Percy his tattoo, but whispers to Percy that he hoped it hurt. He later claims that Camp Jupiter will get good luck.
At the senate meeting the following day, Percy informs all of Rome about the existence of Camp Half-Blood and that he is, in fact, a Greek. He also informs Rome of the imminent arrival of the Argo II, whose passengers were coming to help fight against Gaea. Octavian was one of Percy's fiercest opponents at the meeting, claiming that Greeks were Rome's enemies, and shouldn't be trusted. He demands that the Romans take military action against the Greeks, saying that they should destroy them before they have a chance to land. When Percy says that the Greeks are peaceful and that Jason was on board, Octavian accuses him of lying and once the ship comes into view, he begins to scream "Beware Greeks bearing gifts!" He points at Percy accusing him of leading the Greeks to the camp. However, Reyna says that they will allow them to land, but the Legion forces would be ready if it was a trick. Octavian opened a stuffed animal and says these omens are horrible and death is coming. After they agree to give the "Greeks" peace, Octavian walks out of the senate in disgust.
Octavian coldy greets the Greeks and Jason when they come off the Argo II. While talking about the quest, Ella says the entire prophecy, causing Octavian to become suspicious for what she said. Later, when Percy offers to give back Jason his praetorship, calling it "no biggie," Octavian becomes outraged saying, "The praetorship of Rome is "no biggie?"
When Leo Valdez unwillingly attacks the Romans, Octavian is one of the first to retaliate and start war between them and the seven, convincing the Romans that Greeks are enemies and they must pay for what they have done. The seven rush back to the Argo II, and quickly leave, causing the Romans to pursue them.
In Charleston, the Romans find the seven thanks to Octavian and his auguries. Percy douses Octavian in water to stall him. He is later seen through Katoptris with Reyna, looking at an invasion map in New York.
Octavian is extremely ambitious and power-hungry, willing to use any means, from extortion to manipulation, in order to achieve his goals. He is portrayed as a somewhat potential threat if one became enemies with him, as Percy said. However, he seems to want to protect the camp and advocates a conservative approach when it comes to its affairs. He considers the Greek demigods to be enemies due to the ancient rivalry between Greece and Rome, and therefore, is very hostile towards Percy and the ideas he brings of truce with the Greek demigods aboard the Argo II.
Octavian is a skinny eighteen-year-old with blond hair, crazed blue eyes, and pale skin. He wears a white toga over a blue shirt and jeans. It is also mentioned that Octavian reminded Percy of someone, which means he could be referring to Luke Castellan. He often has a ceremonial knife and stuffed animal on hand. His tattoo is composed of a lyre, the symbol of his ancestor Apollo, with SPQR inscribed above seven lines which represents seven years meaning that he has been attending Camp Jupiter since he was eleven.
Prophecy: Being a descendant of Apollo, Octavian can interpret the will of the gods by reading the stuffing of stuffed animals, which are the modern day version of animal intestines. However, this ability isn't perfect and the messages will sometimes vary between two or more messages.
Hazel openly dislikes Octavian due to his manipulative nature. Octavian tries to get her to vote for him so he could become the new Praetor by dropping a few hints that he knows about her past and that she was dead once, claiming that it would be horrible if the rumors about her turned out to be true.
Octavian dislikes Percy, and the feeling is mutual. He doesn't trust Percy because he is a child of the Greek gods, as opposed to the Romans, thinking that the Greeks are working with the forces of Gaea. He is also upset when Percy is elected praetor over himself. When they first meet, he slices open Percy’s panda pillow pet to Percy's dismay, because he had grown fond of it. He shows this dislike after Percy tells everyone not to attack the Greek Demigods when they land but he still tries to rally them to attack.
While the two never seem to spend much time together, it is clear that Octavian believes Reyna is not a good leader. He complains that she won't allow a quest to find a book of prophecies (the Sibylline Books) that he is obsessed with. He also feels that she has let a power vacuum form during Jason's absence. He manages to make any unfavorable decision (such as making Frank a Centurion) seem like it was all Reyna's idea and he is following orders. Whenever Reyna makes a decision he approves of, he tries to make it seem like it was all his idea.
- Octavian is named after Caesar Augustus, a Roman emperor whose birth name was Octavian and was a son of Apollo, Octavian's divine ancestor.
- His name could also be derived from Octabus, Latin for eighth.
- The Ancient Romans used the entrails from sacrificed animals to determine the advisability of any chosen endeavor and event just as Octavian does with stuffed animals. As a ritual before meeting the oracle, the ancient Greeks did as well.
- Octavian is obsessed with the Sibylline Books.
- Although it is never stated how many generations Octavian is from Apollo, his family has been at Camp Jupiter for over a century, so he is at least fourth-generation.
- Despite Octavian being a Roman legacy, his name is Greek.
- Despite Octavian being a legacy of Apollo, he has an uncanny resemblance to Luke Castellan, son of Hermes.
- Despite the fact Octavian is referred to as an Augur, Augury is the ancient practice of divination through watching birds and the heavens. A diviner who foretells the future through the entrails of animals is properly referred to as a haruspex.
- Octavian is named after the member of the second Roman triumvirate Octavian, who later changed his name to Augustus.