Aside from Naruto and his immediate family, characters like Kakashi could also be important in this fanfiction. He was Naruto's mentor, and he would surely be there to welcome them back. And Sasuke might also play a role, as he is Naruto's friend and has a connection to the village too.
In this fanfiction, the Naruto family might be welcomed back with great joy. The villagers could hold a big celebration to honor their return. Naruto, as a hero, would finally be home with his family in Konoha, and his kids might start exploring the village that their father has so many memories of.
Perhaps it's an old enemy who has somehow managed to come back stronger. Maybe someone from Orochimaru's old experiments that went wrong, but instead of dying, they gained some dark and powerful abilities. They see Naruto's return as a threat to their plans of world domination, so they target Konoha first. They might be able to control dark chakra in a way that no one has seen before, and use it to create chaos and destruction. They could also have some minions who are equally as powerful and loyal to them, making them a formidable foe for Naruto and Konoha.
In this fanfiction, Naruto is the key figure. However, characters like Shikamaru, who is known for his intelligence, might also be involved. He could be helping to plan Naruto's welcome or dealing with any potential issues that Naruto's return might bring. Also, Hinata, given her relationship with Naruto, would surely be part of the story. And the elders of the village may also play a role, as they often have a say in important matters regarding the village and its shinobi.
Obviously, Naruto himself would be one of the main characters. His wife, for example Hinata, would also be a main character as she is part of his family. And their children, like Boruto and Himawari, would surely play important roles too.
It could be a rogue ninja who has been secretly building power while Naruto was away. This rogue ninja might have a vendetta against Konoha and sees Naruto's return as a challenge to his plans. So he directly confronts Naruto to prove his own strength.
It could be a rogue ninja from a neighboring village who has a vendetta against Konoha. This ninja might see Naruto's return as an opportunity to take on the strongest ninja in Konoha and prove his own strength.
Sakura could also be a main character. She's a strong ninja in her own right. In a fanfiction like this, she could be involved in treating the injured when the Hellsing - related chaos starts. Maybe she also tries to understand the unique physiology of Alucard. And Integra from Hellsing. As the head of the Hellsing organization, she could be the one trying to establish some sort of order between the two worlds.
Naruto is definitely one of the main characters. He is the key figure in the Naruto universe. His family, which includes Hinata, Boruto, and Himawari, are also likely to be main characters. Boruto, with his own dreams and potential, might be facing some internal or external conflicts. Himawari, being the younger one, could be used to show the family's protective side. And of course, other characters from the original series like Sasuke might also make appearances, as he is Naruto's best friend and they have a deep connection.
His wife could be Hinata. In the original series, there were hints of their relationship. Hinata has always admired Naruto and they would make a great couple. She is a strong and kind - hearted ninja from Konoha, which would make for an interesting dynamic when Naruto returns with her as his wife.
Well, Naruto's friends and comrades from his past adventures are likely to be in it. But also, there could be some spiritual or mythical characters related to the concept of the golden fox. For example, there might be an old sage who knows the secrets of the golden fox and can guide Naruto on how to use its power properly. There could also be other villages' representatives who come to Konoha to see this 'Naruto with the golden fox' phenomenon and see if it poses a threat or an opportunity for their own villages.