Another possibility could be Sakura. Although she has her own relationship with Sasuke in the original, in fanfiction, the writer could change the storyline. Sakura might end up with Naruto for some reason and then betray him. It could be because of her unfulfilled feelings for Sasuke resurfacing or some other internal conflict within her.
Hinata could be a likely candidate in such a fanfiction. Since she is Naruto's real - life wife in the original series. Writers might twist their relationship in fanfiction and create a scenario where she betrays him. Maybe due to some family pressure or a misunderstanding that gets out of hand.
Perhaps his wife betrays him out of jealousy. She could be jealous of Naruto's status and the attention he gets. So she leaks some of his secret plans to the enemy. As a result, Naruto's missions start to fail and he becomes a target. He then has to face not only the external threats but also the heartbreak of his wife's betrayal. He might start to question his own judgment in choosing her as his partner.
It could be due to a power imbalance. If Naruto's power as Hokage makes her feel overshadowed or unimportant, she might be led to betray him. Also, perhaps she discovers some long - hidden secret about Naruto that she can't forgive, like a connection to a past enemy or some dark side of his shinobi past that he has kept from her.
In the Naruto - Star Wars crossover fanfiction, Anakin Skywalker could be a likely character to be betrayed. He has a complex personality and a lot of power. In the Star Wars canon, he was already betrayed by the Jedi Council in his view, which led him to the dark side. In a crossover, he could be further betrayed by a Naruto character who might misjudge him or be deceived by the Sith. Another could be Naruto himself. His trusting nature makes him vulnerable. A Star Wars villain could easily deceive him and then betray him when he is no longer useful.
He could initially go into denial. Naruto has always been an optimist. He might not be able to believe that his wife, the person he loves, could betray him. But once the truth sinks in, he would start to analyze the situation carefully. He might try to find a way to redeem her, depending on the nature of the betrayal, as he always believes in the power of forgiveness and second chances.
A possible character could be a fellow Hogwarts teacher. Maybe a new potions teacher who shares Snape's passion for the subject. They could start off as rivals in the classroom but gradually fall in love as they discover their shared interests and values.
Perhaps an old enemy from Naruto's past that was thought to be defeated has resurfaced. This enemy might have targeted Naruto's wife as a way to get revenge on Naruto for their previous defeats. They could be using her as a bait to lure Naruto into a trap.
She might be an original character created specifically for the fanfiction. This character could be a witch from a far - off land with unique magical powers. She comes to Hogwarts on some sort of exchange program and meets Snape. Their relationship starts off as a friendship that gradually blossoms into love.
It could be a powerful new villain who wants to get back at Naruto. Maybe someone from a rival village who thinks stealing his wife will weaken him.
In some fanfictions, it could be Hinata. They have a strong connection in the original series, and it would be a natural progression for them to get married and start a family.
Sasuke could also be a character who is frequently betrayed in these fanfictions. Given his complex personality and his history of being both a loner and a seeker of power, he might be lured into dangerous alliances in the DxD world. And his partners in the DxD world could betray him when they realize they can't control him or when his power becomes a threat to them.