His physical strength might increase. Thor is known for his great strength, and as his adopted son, Percy could inherit some of that. He might be able to lift heavier objects or fight more powerfully in close - combat situations. Maybe he could even hold Mjolnir for a short period of time, which would be a huge boost to his powers and status in both the Greek and Asgardian worlds.
His powers could also gain a new aspect related to storms. Combining his water - based powers with Thor's storm - creating abilities, Percy could summon water - filled thunderstorms. He could use these to flood areas or create powerful lightning - filled rainstorms to defeat his foes, making his powers far more versatile and dangerous than before.
His powers could become more ice - related. Since Khione is the goddess of snow, Percy might gain the ability to freeze water instantly. For instance, instead of just controlling water, he could turn it into ice sculptures or use ice as a weapon, like creating ice shards to throw at enemies.
His powers might become more related to Hera's domain. For example, he could gain some control over marriage and family bonds. He might be able to sense when relationships are in trouble or strengthen the loyalty between people. Also, his existing powers could be enhanced in a way that reflects Hera's influence. Maybe his water - based powers could be more refined and have a new aspect to them, like being able to purify water to heal emotional wounds as well as physical ones, since Hera is associated with purity in some ways.
Well, when it comes to Percy's relationships in this fanfiction scenario, it's really a big shift. His bond with his mother would be affected as she tries to understand this new part of her son's identity. His relationship with Grover would have an interesting turn. Grover might see Percy as even more of a protector figure now, but also be concerned about the changes. And Percy's relationship with the minor gods would change too. They might approach him, hoping to gain some favor or protection through his link to Ouranos. Overall, Percy's relationships would be in a state of flux, with everyone trying to figure out how to interact with him in this new role.
Percy would likely become more studious. Since Athena values knowledge, he would be more interested in learning about history, magic, and other aspects of the demigod world. He might spend more time in the library at Camp Half - Blood, much to the surprise of his friends. His relationships with others would also change. He could be more aloof at first as he tries to adapt to his new role, but as he grows into it, he would form deeper, more intellectual connections with those around him.
His powers would likely become more god - like. He might gain the ability to control lightning, like Zeus. Also, his strength and speed could be enhanced to a much greater degree. His control over water, which was his main power before, could also be amplified and perhaps combined with his new lightning powers in some unique ways.
If Percy is a descendant of Kaguya, his powers might change in a way that combines his demigod abilities with some unique Japanese - inspired powers. For example, he could gain the power of illusions, like Kaguya was said to have in some stories. This would be a new and unexpected addition to his combat and survival skills. He could use these illusions to deceive enemies or find hidden paths. Also, his speed and agility might increase, as Kaguya was often depicted as a very graceful and swift figure.
Percy's water - based powers could interact interestingly with Thor's lightning. For example, water is a great conductor, so if Thor were to strike Percy's water constructs, it could create a powerful blast. Or Percy could use his control over water to create a shield against Thor's lightning, diffusing it in a spectacular show of power.
Thor's ability to fly with his hammer could be enhanced by Percy's control over water. Percy could create a water - spout or a current of water in the air that Thor could ride on, increasing his speed and maneuverability. In turn, Thor could use his strength and lightning to protect Percy when he is using his water powers in a vulnerable state, like when he is concentrating on creating a large - scale water structure.
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.
The Son of Thor would interact in diverse ways. With Annabeth, he could have some intellectual exchanges. She might be intrigued by the Norse mythology he represents and how it compares to Greek mythology. Grover would be friendly towards him, and they could share stories about their different worlds while on a journey. As for Percy's other friends, the Son of Thor would bring his own sense of honor and strength, which could earn him respect or cause some friction depending on the situation.