One thing that could be done is simply respect his opinion. Don't try to force him to read or like poker fanfiction. If others like it, they can enjoy it among themselves without involving Percy.
Maybe Percy just doesn't like the whole idea of combining poker with fictional stories. It could be that he finds the concept of writing fanfiction about poker really unappealing. For example, he might think that poker is a serious card game and doesn't fit well with the often creative and sometimes out - there nature of fanfiction.
He could play with the gods. Imagine Percy sitting down at a table with Zeus, Poseidon, and Hades. Each of them has their own motives and strategies. Zeus might try to use his power of lightning to intimidate the others, while Poseidon could subtly influence the flow of water in the drinks on the table to gain an edge. Hades would be silently observing and making calculated moves.
Perhaps Percy doesn't have the right group of friends to play poker with. If his friends are all into different kinds of activities, like studying magic or fighting monsters, there may not be anyone around to initiate a poker game. So, he just never gets into it.
Maybe Percy just doesn't like the complexity and strategy involved in poker. In fanfiction, authors often create characters with specific personalities and interests, and perhaps poker simply doesn't fit into Percy's character profile.
Well, it could be that Percy has had some really bad experiences in his life that made him bitter towards everyone. Maybe he was betrayed by friends in the past, so now he just can't bring himself to trust or like anyone.
If someone really wants Percy to at least tolerate it, they could try to find beer fanfiction that is more tastefully done or that has a different take on the concept. Maybe some fanfiction that uses beer in a more symbolic or light - hearted way rather than in a way that might be off - putting to Percy.
Maybe Percy is on a quest and stumbles upon a group of magical creatures playing poker. They invite him to join. Percy, being Percy, is a bit clumsy at first but then realizes that the game has a deeper meaning related to the prophecy he is part of. He starts using his battle - trained mind to analyze the opponents' moves and the patterns of the cards, all while trying not to reveal his true identity as a demigod.
Well, one reason could be that fanfiction often takes creative liberties that might distort the original relationship between Poseidon and Percy in the official story. It could be that Poseidon is a very complex character in the original, and fanfiction simplifies or misrepresents him in a way that makes it seem like he 'hates' Percy in those fictional interpretations.
Obviously, Percy would be the main character. But there could also be other characters like his family members who might be trying to figure out why he has such a negative attitude. Maybe there's a best friend from his past who he now hates but who still tries to reach out to him.