Surprisingly, some of the creatures in the wizarding world could be his allies. The house - elves, known for their loyalty, might help Harry if they believe he has been wronged. They could use their magic to smuggle things in and out of the prison for Harry. And the centaurs, with their deep knowledge of magic and the forest, could provide valuable information or even a place for Harry to hide if he manages to escape.
Hermione and Ron would surely be his top allies. They've been through so much with Harry and would stop at nothing to prove his innocence. Hermione's intelligence would be crucial in finding loopholes in the false charges and Ron's loyalty and courage would keep them going in the face of danger.
Hedwig could be a potential ally. She could carry messages to Harry's friends at Hogwarts, alerting them of his situation. Even though she is just an owl, she has shown loyalty and intelligence in the original series.
Hermione would definitely be one of his allies. She is smart and would be able to help him research about his new identity and how to control his powers. For example, she could find ancient texts in the Hogwarts library that relate to both the wizarding world and the Greek gods.
His friends from Hogwarts could still be his allies. Hermione would use her intelligence to help him understand his new situation. Ron would be there for moral support. Additionally, any friends or allies that Rias has in her world could also become Harry's allies. They might be magical creatures or other powerful mages.
Hermione would definitely be an ally. She's smart and would be able to help Harry research about his 'son of Mars' heritage, finding ancient spells or texts that could explain it further.
In this fanfiction, some of the potential allies for Harry could be the magical creatures that have a connection to Norse mythology. For example, the Valkyries. They could help Harry in battles or in understanding his new heritage. Another ally could be Odin, Frigga's husband. Despite the initial shock of Harry's existence, he might see the value in Harry and offer his protection and guidance. And don't forget Neville. He's always been a loyal friend to Harry, and in this new scenario, he would continue to be an ally, perhaps even more important as Harry faces new and different challenges.
One potential ally could be Hagrid. Hagrid has always been a friend to Harry, and in this fanfiction, he could help Harry understand his newfound heritage as the son of Hephaestus. Hagrid's knowledge of magical creatures could also be useful in Harry's adventures related to his Hephaestus - given abilities.
Dumbledore could be a powerful ally. He has a deep understanding of magic and would be interested in exploring Harry's new abilities. Also, some of the more open - minded members of the Order of the Phoenix might see the potential in Harry's unique heritage and support him, like Lupin or Sirius if they were still alive in the fanfiction.
Some potential new allies could be the house - elves. They might see Harry's plight and decide to help him, using their unique magic and knowledge of Hogwarts' secrets. Another could be the centaurs in the Forbidden Forest. They are very wise and may take Harry under their wing.
Naruto might initially be in shock and disbelief. He has always been loyal to the village, so being imprisoned for no real reason would be a huge blow. He would probably start by trying to reason with his captors, explaining that he is innocent. For example, he might say things like 'I've always protected this village, why would I do what you're accusing me of?'
Hermione could still be a great ally. She's smart and observant, so she'd probably be able to figure out ways to communicate with Harry even if he's mute. Also, Hagrid. Hagrid has a big heart and he would see past Harry's inability to speak. He would likely take Harry under his wing just like in the original story.