Athena might also be a good candidate. Although she and Poseidon have their differences, she could see Percy's potential and befriend him. She could offer him wisdom and strategic advice for his various adventures.
Well, there could be Percy going on quests with the gods by his side. Maybe they help him face new and more powerful monsters that he couldn't handle alone. For example, fighting a giant that has been awakened by an ancient curse.
Grover might be the most likely to resist. He has always been very connected to the mortal and natural world. His role as a satyr has been to protect and guide demigods in the mortal world. Becoming a god would mean leaving behind his familiar role and the simple joys of the natural world he loves so much. He might fear losing his identity and his close connection to the forests, meadows, and the young demigods he has befriended over the years.
One possible plot could be that Percy and his friends are faced with a new and extremely powerful threat that endangers not only the mortal world but also the entire pantheon. In order to defeat it, they are offered a chance to become gods. They have to go through a series of trials that test their loyalty, courage, and wisdom even more than before. Percy might struggle with the idea of leaving his mortal life and family behind, but realizes it's for the greater good. Along the way, they face old enemies who are jealous of their potential ascension and try to stop them at all costs.
Maybe Percy unknowingly breaks some ancient and very strict laws of the Gods. For example, he might interfere with some sacred rituals or places that are off - limits to mortals, even demigods like him. In the fanfiction world, the Gods could be very unforgiving when it comes to such violations and decide to kill him as a result.
Yes, it is quite popular. Some fans like to explore alternate storylines where Percy takes extreme actions like this. It adds a new level of drama and reimagines the power dynamics in the Percy Jackson universe.
Well, in some fanfictions, Zeus and Poseidon have a 'divine argument' over who has the better beard. It's really silly but makes for a great read. Also, Aphrodite trying to give makeovers to the other gods against their will can be extremely humorous. For example, she once tried to put makeup on Ares in a fanfic, and Ares' angry reaction was a riot.
In fanfiction about Percy Jackson Gods' Promises, one common aspect is the exploration of how the gods' promises shape the characters' fates. For example, Percy might be directly or indirectly affected by a promise made by Zeus or Poseidon. These promises often add an extra layer of complexity to the story, as they can be broken or fulfilled in unexpected ways.
Another theme is the creation of new quests. Fanfiction writers often come up with unique quests for Percy and his friends. These quests can involve different mythologies or new challenges that are not in the original books. For instance, a quest that takes them to a hidden realm full of forgotten gods.
One great 'Percy Jackson and the Gods Fanfiction' is 'The Lost Hero's Return'. It has an exciting plot where Percy comes back after being lost in a mysterious realm. The author does a wonderful job of staying true to the characters' personalities from the original series.