His powers would be unique in that he could have a natural affinity for the Underworld's environment. He might be able to sense changes in the Underworld's energy, which could help him predict incoming threats from there. Also, he could have the power to manipulate the Underworld's minerals and gems, which could be used for various purposes, like creating powerful weapons or magical artifacts. This is different from normal demigods who usually have powers related to their Olympian parent's main domain, like a child of Poseidon having water - based powers.
Percy could have the power to manipulate the coldness that is often associated with the Underworld. He could freeze his opponents or create ice - like structures out of the cold energy. This would be different from his water - based powers in the normal story. Also, he may have a stronger connection to the gems and precious metals that are found in the Underworld, being able to sense them and even use them in some way for his benefit.
In a fanfiction where Percy is the son of Hades and Poseidon, his powers would be truly extraordinary. He could have the ability to create portals in water that lead to the Underworld. This would give him an advantage in both battle and travel. His hydrokinesis could be tainted with the essence of death, so when he attacks with water, it could cause a draining effect on his opponents, sapping their life force. Additionally, he might be able to sense the presence of the dead in any water source, which could be used for both reconnaissance and protection.
Well, Percy's new powers could include the ability to communicate with creatures of the night in a way he couldn't before. Maybe he could call upon the help of shadowy beasts or entities that are associated with Nyx and Erebus. His strength might also be tied to the level of darkness around him. In a pitch - black place, he could be extremely powerful, while in bright sunlight, his powers might be somewhat weakened.
He might have a darker complexion, similar to the shadowy realm of Hades. His eyes could be a deep, almost black color, with a faint glow, representing his connection to the underworld. His hair might also have a slightly darker hue or even a bluish - black tint, like the color of a moonless night.
Percy, as the son of Bastet, would likely have powers related to feline - like abilities. For example, he might have enhanced speed, agility, and reflexes compared to other demigods. His senses, especially his sight and hearing, could be much sharper. Also, he could potentially have some sort of connection to cats, being able to communicate with them or understand their behavior in a way other demigods can't.
One way to develop the storyline could be to explore Percy's struggle with his new identity. Since Hades and Persephone are such complex deities, Percy might have a darker side to him. He could struggle with controlling powers related to the Underworld, like shadow manipulation or communicating with the dead. For example, in a school setting, he might accidentally let out some spooky manifestations when he's stressed.
Well, instead of summoning water or having a connection with the sea, he might have the power to shift shapes, a common ability associated with Loki. He could turn into different animals or even other people to gain an advantage in a fight or to infiltrate an enemy's stronghold. Also, his power over fire could be enhanced, as Loki has some association with fire in Norse mythology. He could use this to create distractions or attack opponents from a distance.
Well, Harry's magic is based on spells and the use of a wand. Hades' power is more about controlling the underworld, death, and the souls there. Persephone has power over nature, especially in relation to the underworld. If they were in a situation together, Harry's magic could potentially be used to protect the living from any threats that Hades' underworld - related powers might pose. For example, if some undead creatures escaped the underworld, Harry could use defensive spells.
Naruto, as the son of Hades, would have some really cool powers. His Rasengan could potentially be infused with the power of the Underworld, making it a much more deadly attack. He could also have the power of persuasion over the dead, which means he could make them tell him secrets or do his bidding. His ability to sense chakra in the Naruto world could be translated into sensing the life force or the 'essence' of beings in the Percy Jackson world. This would give him an edge in detecting enemies, whether they are living or undead.
Percy's powers would be more complex. He could have the ability to communicate with sea deities in a different way. Maybe he could use Hera's diplomatic skills to make deals with them or resolve disputes. His control over water could also be extended to other substances that have a connection to water, like steam or ice, in a more efficient way than before. And his powers of persuasion, which could be influenced by Hera, might be used to calm angry sea storms or make sea monsters cooperate with him, which is an interesting combination of his Poseidon - given powers and Hera - influenced skills.