Well, it could be about Naruto having the powers or traits similar to Achilles. Maybe he has superhuman strength like Achilles was known for. He could also inherit some of Achilles' courage and tenacity, which would make him even more formidable in battles in the Naruto universe.
Well, the plot could involve Percy being in the shadow of Achilles at first. Since Achilles is so well - known in Greek mythology. But then, a great danger arises that only the combined powers and skills of both of them can overcome. They have to journey to the Underworld to stop a dark force from escaping. During this journey, they reconcile their differences and strengthen their brotherly bond as they face the terrors of the Underworld.
One possible plot could be that the child grows up in the shadow of their famous parents. They might struggle with the expectations placed on them due to their parents' heroic and tragic story. For example, they could be trained in combat like Achilles, but also inherit Briseis' kindness and compassion, which would create an internal conflict as they try to find their own identity in a world that only sees them as the child of two legends.
The fanfiction could involve a prophecy related to the unborn child. The prophecy might state that the child will either bring great peace or great destruction. This would put a lot of pressure on Achilles and Briseis. They would have to decide how to handle this knowledge. Do they try to hide the child's existence? Or do they raise the child to be a force for good? Achilles might also become more protective than ever, leading to some tense moments with his comrades who don't fully understand his newfound intensity.
Perhaps in this fanfiction, Achilles discovers a prophecy that if Troy falls, it will lead to the destruction of his own homeland in a different way. So, he fights for Troy not just as a hired warrior but as someone with a vested interest in the city's survival. He uses his incredible combat skills to fend off the Greek invaders, and along the way, he forms unexpected alliances with some of the Trojan soldiers who were initially skeptical of him.
Perhaps there's a dark entity that was once an enemy of Achilles in the original mythology. And now that Naruto is the son of Achilles in the fanfiction, it targets him. This entity could have powers that are specifically designed to counter Naruto's Achilles - related powers, making for some intense battles.
In a 'naruto son of bellatrix fanfiction', perhaps Naruto has some of Bellatrix's wild and unpredictable nature. He could be on a journey to discover his true identity and how he came to be Bellatrix's son. This might lead him to explore the secrets of the wizarding world and his own ninja abilities in a new light.
Well, one possibility could be that Naruto inherits some of Gilgamesh's arrogance along with his power. Maybe he has a special ability to summon ancient Babylonian weapons. And he could use this in his battles in the Naruto world, like against the Akatsuki.
One possible plot could be that Naruto discovers his true heritage as the son of a princess from a hidden kingdom. He then has to deal with the politics and expectations of the royal family while still maintaining his ninja ways. Maybe he has to protect the kingdom from a new threat using his ninja skills.
In such a fanfiction, perhaps Naruto could be shunned by the village from the start. His 'devil' heritage might give him strange powers that he has to hide. He could struggle with self - identity, different from the Naruto in the original who is seen as a hero. Maybe he has to fight against the prejudice of the people who believe the devil's son can only bring destruction.
Well, it could be about Naruto having powers related to Hades on top of his ninja skills. Maybe he can control the dead or has some sort of underworld - like abilities that he uses in battles against the Akatsuki. He might also have to deal with the stigma of being the son of Hades in a world that doesn't understand such a thing.