Hinata might be a character who is betrayed in Naruto DxD fanfictions. She is often shy and gentle, and in the DxD world, she could be taken advantage of. For example, she might befriend a group of devils who seem friendly at first but later betray her when they find out about her special abilities or her connection to Naruto.
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.
He could be betrayed by a false friend in the DxD world who spreads lies about him. For instance, telling others that Naruto has a hidden agenda to take over their realm.
Even Hinata could potentially be written as a betrayer in some really out - there fanfictions. Maybe in a crossover where there are mind - control elements, Hinata could be forced to turn against Naruto. But this would be a very different take on her character as she's usually portrayed as extremely loyal to Naruto.
Well, obviously Naruto himself is the central character. Sasuke could be involved as he has a complex relationship with Naruto. In a crossover, if Naruto is betrayed and ends up in the Dragon Ball universe, Vegeta might be a character he interacts with. Vegeta could initially see Naruto as a weakling but later come to respect his skills. Another character could be Luffy from One Piece. If Naruto is betrayed and crosses over to the One Piece world, Luffy would likely befriend him and help him out, seeing Naruto's situation as similar to his own crewmates' struggles.
Obviously, Naruto would be one of the main characters. He's the one being betrayed. From RWBY, Ruby, Weiss, Blake, and Yang are likely to be involved. They are the central characters in RWBY, and if there's a betrayal of an outsider like Naruto, they would probably play a significant role in it.
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.
The village elders are often depicted as the ones involved in Naruto's betrayal. They might see him as a threat to their power or the stability of the village. Also, some fanfictions might involve Danzo. He has always been a bit of a shadowy figure in the Naruto series, and his underhanded ways could easily be written into a plot where he is behind Naruto's false accusations and subsequent banishment.
In such a fanfiction, Naruto might be betrayed by his new allies in the DxD world due to misunderstandings. For example, his powerful jutsu could be misconstrued as a threat. His loyalty to his own ninja way might clash with the values of the DxD characters, leading to a rift.
Cinder Fall could be a likely betrayer. She's already a villain in the original series, and in a fanfiction, she could pretend to be an ally to one of the RWBY members only to betray them at a crucial moment, perhaps leading them into a trap set by Salem.
One possible fanfiction idea could be that Naruto, who somehow ends up in the world of High School DxD, is betrayed by some of the devils there. Maybe they initially seem friendly but then backstab him for his power or because they fear his potential. Naruto, being the resilient character he is, would then have to find a way to overcome this betrayal and prove himself.
One possible scenario in such a fanfic could be that Naruto is betrayed by his new comrades in the DxD world. Maybe they misunderstand his motives or are jealous of his power. For example, they might think he's using his abilities for his own gain rather than the common good.