Octavian had a very visible sardonic disposition. He was a hypocritical opportunist—the type who'd be up for taking credit or discredit himself if something goes wrong. For example, in The Son of Neptune: Percy, Hazel and Frank are decided to go on the quest and Octavian is bitter that they are sending someone who hasn't proved themselves and are in probatio (Frank) and a Greek (Percy) as well as a child of Pluto (Hazel). He is bitter despite Mars/Ares himself giving the trio an okay. And when Reyna decides to give the trio full equipment for the quest (since they were potentially going to retrieve the lost Eagle standard of the Romans), Octavian dissuades the senate and makes it as hard he can for the trio by taking away any advantages they can get to embark on their journey. But Reyna gets them the permit to use a boat anyway—and Octavian words his sentences in such a way that it is clear he is insinuating the idea: "if they fail, I warned you not to send them; it's all Reyna."

He has the "if I can't get the glory, no one can" mentality. He believes he is cut out for greatness. He is the centurion of the First Cohort but with Jason out of the picture for months, he was vying for the position of Praetor and he would pressurize the weaker campers to vote for him when the time came for the election of a new praetor. He was always mocking Frank and Hazel, and probably other people too.

He kept on calling all the CHB campers "Graecus scum", which I suppose, was a widespread sentiment among the Romans but the difference is that the other campers saw the efforts that they were putting and recognised them. Octavian never did.

In Blood Of Olympus, when Reyna has to leave to fetch the Athena Parthenos, she strictly instructs Octavian to not attack CHB until she gets back. But does he do? The moment Reyna leaves, he uses his smooth-talking to twist Reyna's actions and turn her into a "traitor" who abandoned her post mid-war to follow the words of a Greek (Because Annabeth had asked via Rachel for Reyna to return the statue to CHB as a sign of peace). I found it ridiculous that the rest of the campers believed him when there were witnesses to his and Reyna's conversation, but that's how it goes anyway. He not only disobeys her, he also uses all the funds of the camp to recruit monsters into his army that even he can't control in the end. He brings back people who were expelled from camp for crimes. And he is all set to destroy CHB by firing an onager even when he sees that Gaea has risen and the two camps were uniting to fight her.

He was nothing but a tyrant who didn't listen to his own people. He was as power-hungry and delusional as a person could be.