The heir of Pontus is the central figure. They will have their own personality, goals, and struggles. Alongside them, if the fanfiction is set in the Percy Jackson universe, characters like Grover could make an appearance. Grover might be involved in guiding the heir in some way, or he could be a sidekick during their adventures. Also, there could be villains in the form of other powerful beings from the sea or those who want to take advantage of the heir's power. For example, a sea witch - type character who tries to manipulate the heir.
The main character is the heir of Pontus, of course. In addition to that, some fanfictions may introduce a group of characters who are descendants of other minor sea gods. These characters could be friends or foes of the heir. Then there are the regular characters from the Percy Jackson series that are likely to be involved. For instance, Tyson, Percy's cyclops half - brother. He could be a valuable ally to the heir, providing his strength and knowledge of the sea world. Also, there might be a human character who stumbles upon the world of demigods and the heir, and they play a role in the story, either as a love interest or a source of help in the human world.
Well, one interesting plot could be the heir of Pontus having to deal with new and strange sea monsters that are loyal to Pontus. They might have unique powers and abilities that the heir has to figure out how to control or defeat. Another plot could involve a power struggle between the heir and other demigods who fear the power of Pontus. And sometimes, there are plots where the heir discovers long - lost secrets about Pontus' realm and has to protect them from falling into the wrong hands.
Perhaps an ancient sea god who was once an enemy of Pontus. This god could see Percy as a threat because of his heritage. He would use his own minions, like sea serpents and murlocs, to attack Percy and those he cares about. He might also try to corrupt Percy, tempting him with power to turn against his friends.
Well, Percy Jackson is most likely one of the main characters, given that his name is in the title. And since it's related to the Percy Jackson universe, Annabeth Chase could also be a main character. She often plays a significant role in Percy's adventures. Also, if the 'Heir of Black' is a new character, that would be a main character too.
Well, in fanfiction, if Percy is the Champion of Pontus, his story would be filled with more mystery. Pontus is an ancient and powerful entity. Percy might be called upon to do things that go against the traditional ways of the Olympian - influenced world he's used to. He could discover secrets about the origin of the sea and his own powers that were previously unknown. This would not only make for an exciting read but also show how Percy can adapt and make his own path even when given a very different role.
The Titans who were once associated with Pontus might be antagonists. They could see Percy as a threat to their plans if he is related to Pontus. They might try to stop him from fulfilling any tasks given to him by Pontus or try to use his new identity against him.
The other gods might be antagonists. Since Percy is the son of Gaea and Pontus, the Olympian gods could see him as a threat. They might be worried that he'll side with his primordial parents and disrupt the balance they've been trying to maintain. So, they could send their demigod children or even some minor gods to oppose Percy.
Obviously, Percy Jackson is one of the main characters as he is the son and heir of chaos in this fanfiction. His friends from the original series like Annabeth Chase could also be main characters. They would likely play important roles in supporting Percy on his new journey and dealing with the implications of his new status.
One possible plotline could be Percy having to fight against other champions of different deities who see him as a threat. Another is that he has to find a way to combine his new role with his loyalty to his friends and the Olympians. For instance, he may be forced to make a choice between following Pontus' orders that might seem harsh to his friends or standing by his friends and risking the wrath of Pontus.
Percy Jackson himself is obviously very popular as he is the main character. His friends like Annabeth Chase also tend to be popular as readers are interested in how their relationships develop. Grover Underwood is another one that fans like to see in these fanfictions, especially when he uses his satyr abilities to help Percy on his adventures as the heir of chaos.
Draco Malfoy would be a likely character. Given his Slytherin status, he would likely have a complex relationship with Percy. He might start off as hostile, seeing Percy as an outsider, but then they could end up having to work together for some reason.