Probably Poseidon, as he is Percy's father and has a vested interest in his son's well - being. Zeus might also be protective in some cases, despite their past differences, as Percy is a hero who often saves the world which benefits Zeus's realm as well.
The unique combination of the gods' involvement and the character Percy Lemon might make it special. It could bring out interesting interactions and storylines that are different from the original works.
You can start by looking on popular fanfiction websites like FanFiction.net or Archive of Our Own (AO3). Just type in 'the gods love percy' in the search bar and you'll likely find a bunch of relevant stories.
In the fanfiction 'When the Gods Love Percy Too Much', the story explores what happens when the gods' love becomes almost overbearing. Percy has to navigate his own life while also dealing with the gods constantly interfering in the name of their love. It's a really unique perspective on the character.
Well, without reading the specific fanfiction, it's hard to say exactly who Percy is. But generally, in a 'champion of the gods' scenario, Percy would be a central figure. He might be a hero with unique powers, like being able to control certain elements or having superhuman strength. He could be a character who has to face various challenges and tasks on behalf of the gods, kind of like a chosen one in a fantasy story.
Zeus is a possibility. As the king of the gods, he might see Percy's potential and adopt him to have an ally among the demigods. Another could be Poseidon, since Percy is already his son in the original story. It would be an interesting twist to have Poseidon formally adopt Percy in a more divine way.
The gods might show their protection in various ways. For example, they could directly intervene in battles Percy is in, using their divine powers to shield him from harm. They might also send him signs or omens to guide him away from danger.
Zeus is often one of the main gods showing possessiveness. He sees Percy as a powerful asset or a potential threat, so he wants to keep Percy in check. Poseidon, as Percy's father, also shows possessiveness in a different way. He wants to protect Percy but also use his powers for his own purposes sometimes.
One idea could be a fanfiction where Percy uses his powers in a new and unique way to solve a problem that the gods themselves are struggling with. For example, he might find a way to stop a magical plague that is affecting both mortals and immortals. This would show his value and ingenuity, which the gods might appreciate.
One aspect could be that in many Percy Jackson - related fanfictions, Percy being betrayed by the gods often leads to a complete shift in his character arc. He might become more cynical or distrustful. For example, he could start to question his previous heroic deeds and wonder if he was just a pawn in the gods' games all along.