Their relationship can be portrayed as a complex one. They are brothers, so there is an underlying bond of family. However, they also rule very different realms. For example, Hades might be jealous of Poseidon's more 'visible' and vast realm of the sea. At the same time, Poseidon could be envious of Hades' power over life and death in a way. But they also rely on each other in some ways, like when there are threats that could affect both their domains.
Another way is to portray it as a complex relationship filled with envy. Poseidon might envy Zeus's position as the king of the gods, while Zeus could be envious of Poseidon's power over the vast oceans. This envy could lead to various power struggles and tense moments between them in the fanfiction.
In the development of their relationship, they would also have to deal with family matters. The other gods, like Zeus, might try to interfere. But Poseidon and Hades could stand united. They would have to communicate a lot, about their pasts, their fears, and their hopes for the future. Through these deep conversations, they would form an unbreakable bond. Their marriage would be more than just a union of two powerful gods, but a relationship based on mutual respect, love, and the shared goal of creating a new order in the mythological world.
Poseidon might be presented as a rather powerless god in the context of Percy being abused in fanfic. Despite being Percy's father, he could be constrained by the will of Zeus and other gods, which prevents him from acting decisively to save Percy. Hades, however, might be a more interesting character. He may have his own motives for helping Percy. He could see Percy as a useful tool against the other Olympians or simply as a victim who he can relate to, given his own outcast status among the gods. So, in fanfic, he might play a key role in Percy's journey to overcome the abuse.
One plot idea could be that Hades and Poseidon have to team up to face a new, powerful threat from the underworld that is starting to seep into the seas. They have to combine their powers, Hades' control over the dead and the underworld, and Poseidon's mastery of the seas. Another could be a story about their childhood, how they supported each other during the early days in Olympus when they were often overshadowed by Zeus. Maybe they shared a secret adventure that no one else knew about.
The relationship could be shown as a curious one. Since Percy is a baby, he might not fully understand who Poseidon is, but there could be an instinctual bond. Poseidon, on the other hand, could be filled with a sense of wonder at this small version of his son, seeing all the potential in him. He might try to communicate with Percy in gentle, non - verbal ways, like sending small ripples of water to make Percy laugh.
One unique way is to give them a shared hobby. Let's say they both love to paint. Hades paints the dark and gloomy landscapes of the Underworld, and Persephone paints the vibrant and colorful scenes of the mortal world. Through their art, they understand each other better. Also, you could show their relationship as a bit of a role - reversal. Maybe Persephone is the more assertive one in the relationship, and Hades is the one who is a bit shy and reserved. And for a more complex portrayal, you could make their relationship a bit of a mystery to each other. They keep secrets from each other, not out of malice, but because they are afraid of how the other will react, and as they gradually uncover these secrets, their relationship deepens.
Their relationship could be shown as a sort of mentorship. Poseidon, as the all - powerful god of the sea, could be teaching Percy the more subtle and complex aspects of his powers. For example, how to control the tides in a way that is not just about brute force but also about finesse. This would make their relationship more than just a father - son bond but also one of teacher and student.
In fanfiction, Naruto and Obito could have a very complex relationship as brothers. Obito, with his troubled past, could be both a source of protection and a cause for worry for Naruto. Naruto's positive nature might initially be at odds with Obito's more jaded view, but over time, Naruto could help Obito see the good in the world again.
One way is by showing his love for his family in the Underworld. He could be a caring father figure to the spirits there. Another is by making him a protector of the secrets of the afterlife, which is crucial for the stability of the cosmos.
The relationship can also be shown as very loving. Poseidon might secretly watch over Percy and be proud of his son's achievements. He could send signs of his support during Percy's battles or quests. And Percy, in turn, is always eager to make his father proud and show that he is a worthy son of Poseidon.