It could also be an original character created specifically for this fanfiction. This new character might have some special qualities or a unique backstory that draws Naruto to her. The marriage would then be about exploring a completely new relationship and how Naruto grows with this unknown person in his life.
Another possibility is Sakura. Although she has feelings for Sasuke in the original, in this fanfiction, the story could be rewritten so that she realizes her true connection with Naruto and they end up getting married at 12. Their dynamic would be quite different from the original, with Naruto having to prove himself in a new way to Sakura.
Hinata is a very likely candidate. She has always had strong feelings for Naruto and in a multi - marriage scenario, she could be one of the first to be considered. Sakura could also be a possibility. Despite her initial feelings for Sasuke, in fanfiction, the story could be rewritten so that she realizes her true feelings for Naruto and becomes one of his wives.
It could be Sasuke's sister, if there was one in the fanfiction world. She might share some of Sasuke's traits but also have her own unique personality that attracts Naruto.
He could secretly marry Hinata. In the original series, they have a connection, so in fanfiction, it could be a scenario where they elope or have a secret ceremony for some reason, like to avoid political interference in their relationship.
It could be an original character created specifically for the fanfiction. Maybe an empress from a far - off land that Naruto discovers during one of his adventures.
Maybe Tsukuyomi could be the goddess Naruto marries in fanfiction. Tsukuyomi is associated with the moon. Naruto, with his connection to the Nine - Tails, could have an interesting dynamic with a moon - related goddess. Her powers could help Naruto in controlling the Nine - Tails better or even give him new abilities related to the moon, like enhanced night - time combat skills.
The princess might be from a land that was once at war with the Hidden Leaf. Her marriage to Naruto could be a symbol of peace and unity. She could be a strong ninja in her own right, with skills in stealth and combat, and her personality could be a mix of grace and fierceness.
It could be a long - lost heir to a powerful, almost forgotten dynasty who resurfaces. This heir, being royalty, might have some special powers or knowledge. And Naruto, being the hero he is, could be drawn to her because of her unique qualities and the potential she holds for bringing about positive change in the world.
In this fanfiction, the antagonists might be a group from Koneko's world who oppose her relationship with an outsider like Naruto. They might fear that Naruto will bring chaos or change their traditional ways. They could try to separate them by any means necessary, including using their own unique powers against Naruto. Also, some of the rogue ninja from Naruto's world who are jealous of Naruto's new relationship could also cause trouble.
He could marry Mikasa from Attack on Titan. Just think about it. Naruto's positive and determined personality would contrast with Mikasa's more stoic and protective nature. They could meet through some sort of interdimensional accident. Naruto would be fascinated by the Titans and the world outside his own, and Mikasa might be intrigued by Naruto's ninja abilities.
He could marry Hinata. Even though he's banished, Hinata might follow him because of her deep love for him. Their relationship could develop further outside the village, and they could get married and start a family.