Definitely Annabeth. She has always been Percy's closest confidant. She would be by his side, using her wisdom to help him navigate the complex world of the gods. Tyson, his Cyclops half - brother, would also be an ally. He's strong and loyal, and would be willing to fight for Percy if needed. Additionally, Chiron, with his vast knowledge and experience, could be an important ally, providing advice on how to handle the new powers and the politics among the gods.
His old friends from Camp Half - Blood like Annabeth could be his allies. She would support him through the transition of becoming a god. Grover too, as his long - time friend, would be there for him. Also, some of the minor gods who have always been on good terms with Percy, like Hestia, might offer their help and guidance as he steps into his new role as a god.
In a 'Percy becomes a god fanfiction', Percy's allies could include not only his friends from Camp Half - Blood but also some unexpected characters. For example, Nico di Angelo, who has a special connection with the Underworld, could offer his unique insights. And perhaps some of the nature spirits that Percy has befriended over the years. They would see Percy as someone who has always respected and protected nature, and thus would be willing to stand with him as he becomes a god.