The other gods would probably be very cautious around Percy. Since he's Zeus' younger brother, they would fear that any wrong move towards Percy could anger Zeus. For example, Poseidon might be more respectful towards Percy than he would be to an ordinary demigod, as he wouldn't want to create a rift with Zeus over Percy.
The relationship with other gods would change significantly. Hades, for instance, would be very wary of Percy. He already has a tenuous relationship with Zeus, and Percy being Zeus' younger brother would add another layer of complexity. Hades might see Percy as an extension of Zeus' power and try to keep his distance. The minor gods might also look at Percy as a new figure of authority. They could either flock to him hoping for protection from the more powerful gods or be resentful of another powerful figure in the divine hierarchy. This would all depend on Percy's personality and how he chooses to interact with the other gods in the fanfiction.
If Percy is Zeus' younger brother in the fanfiction, the relationship with other gods would be complex. Athena might see Percy as a potential threat to her influence in Zeus' court. She could try to either befriend Percy to gain an advantage or subtly undermine him. On the other hand, Aphrodite might be interested in using Percy's relationship with Zeus to her own ends. She could try to set Percy up with certain mortals or demigods to create interesting love stories that could also have political implications among the gods.
Some gods might be neutral. They would be more concerned with how this event would disrupt the balance of power among the gods. They might try to negotiate or find a compromise to avoid further bloodshed and chaos in the world of the gods.
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.
The character of Percy's younger brother in Zeus fanfiction could bring new dynamics. He could be a source of conflict, perhaps being jealous of Percy's achievements and trying to outdo him in the world of the fanfiction. Or he could be a support, working alongside Percy against common enemies. It all depends on how the author wants to develop the character.
They could interact in many ways. For instance, Percy's younger brother might be a devotee of Zeus and constantly seek his guidance. Zeus, in turn, could use the younger brother for his own purposes, like having him perform tasks that Percy would refuse.
In a fanfiction where Percy is secretly a god, his relationships with other gods would be turned upside down. Initially, the other gods would be shocked and perhaps a bit resentful that a demigod has ascended to godhood. This could lead to some tension, especially among the more prideful gods. However, over time, Percy could form new alliances. He might work with gods who share his values, such as those concerned with the protection of the natural world. His relationship with his father Poseidon would also change, becoming more of a peer - to - peer bond rather than a father - son relationship with a power imbalance. And with the other Olympians, he would need to navigate the complex politics of the divine world, which would be a whole new experience for him.
If Zeus was Percy's father in a fanfiction, Percy's relationships with other demigods would change drastically. Percy has always been a bit of an outlier among the demigods, but this would take it to a whole new level. Those who were his friends before might start to question his motives. They might wonder if Percy will start to side more with the gods, especially Zeus, and abandon the demigods' cause. Percy would also have to deal with the fact that some demigods might try to use him as a way to get to Zeus. For example, they might ask him to put in a good word for them or try to get information from him about Zeus's plans. This could put a strain on his relationships as he has to figure out who he can trust among the demigods while also dealing with his new identity as Zeus's son.
His personality could change in several ways. For one, he might become more arrogant due to the association with Zeus. However, he could also become more responsible, realizing that he now represents Zeus in a way. He may also grow more distant from his old friends as he has to adapt to his new life among Zeus' domain, which could be full of more formalities and power plays.
With his friends at Camp Half - Blood, Percy might become a bit of an outlier. His connection to Zeus through the blessing could make some of his friends who are more closely tied to Poseidon or other gods feel a bit uneasy. However, it could also earn him respect from those who admire Zeus' power. Percy would have to work hard to maintain his friendships while dealing with this new dynamic.
With his friends from Camp Half - Blood, things would be a lot more complicated. Some might look up to him as someone with extraordinary power, but others might be jealous or feel threatened. His relationship with Chiron would also change. Chiron would have to be extra careful in guiding Percy, knowing that his actions could have far - reaching consequences due to his unique parentage. And when it comes to his enemies, like the monsters, they might be even more determined to defeat him, seeing him as a greater threat to their plans than before.
In the fanfiction, Percy's relationship with Zeus may develop gradually. Zeus, being a powerful and often aloof figure, might initially be distant from Percy. But as Percy shows his courage and abilities, Zeus could start to take a closer interest. This might lead to Zeus mentoring Percy in some ways, teaching him about godly powers and responsibilities.