A new and powerful Titan who has been hiding and gathering strength all this time. He could be jealous of the Olympians' power and wants to take over. Percy would have to figure out his weaknesses and stop him before he causes too much destruction.
One idea could be Percy going on a quest to find a lost artifact that has the power to restore a dying part of the godly realm. This would involve him facing new monsters and making unexpected alliances.
Well, it depends on what you like. If you're a big fan of the Percy Jackson series, it might be interesting as it often takes the beloved characters and the world of Olympus in new and creative directions. Some fanfics in this vein are really well - written and add depth to the existing lore.
One unique aspect might be the way it reimagines the world of Olympus. If Percy is the Flame of Olympus, it might change the power dynamics among the gods and demigods. Maybe it explores how Percy's new status affects his relationships with his friends, like Annabeth, and his interactions with the various gods. Also, it could introduce new mythological elements or creatures that are related to this Flame concept.
Perhaps in this fanfic, Percy is raised as a sort of prince on Olympus. He could be given tasks by the gods to prove his worthiness to be among them. This might include going on quests that are not just for the safety of the mortal world, but also for the stability of Olympus itself. He would also have to navigate the complex social hierarchies among the various gods and goddesses.
One idea could be Percy having to face a new and powerful monster that is immune to water. This would really challenge his typical combat strategies. Another could be Percy getting lost in a forgotten part of the Underworld and having to find his way out while dealing with various underworldly spirits.
There could also be some ancient monsters or spirits that are tied to Olympus' existence. They might rise up to defend it because their own survival is linked to the continued existence of Olympus. These could be powerful beings that Percy has never faced before, adding an extra layer of danger to his quest to destroy Olympus.
Percy Jackson himself is likely one of the most important. He's the hero of the Percy Jackson series, and in this fanfic related to the Bane of Olympus, he would probably be at the center of the action, using his powers and wits to combat the threat.
A possible new character could be an oracle - like figure who is not from the traditional Delphi but is a seer on Olympus. This character could give Percy cryptic prophecies that are related to the future of Olympus and the demigod world. There might also be a group of centaurs who are specifically trained to protect Percy and serve as his advisors, different from the ones at Camp Half - Blood.
It's not likely that the actual Olympus (in the context of the Percy Jackson series being a place of the gods) reads fanfiction. Fanfiction is a creation of the fans in our world, and there's no indication in the books that the gods or Olympus as an entity would engage with it.