Obviously, Naruto and Luna are the main characters. Naruto, the ninja from the Hidden Leaf Village, brings his skills, courage, and determination. Luna, from the My Little Pony world, has her own charm and magic. They are the central focus as Naruto is tasked with protecting Luna.
The main characters are Naruto and Luna. Naruto with his iconic orange jumpsuit and headband, known for his rasengan and shadow clones. Luna, the moon - princess of Equestria, with her elegant appearance and powerful magic. Their interaction forms the core of the story, as Naruto's ninja - way clashes and also combines with Luna's pony - world magic in the context of protection.
Well, it could be that Luna, from My Little Pony, gets into some kind of danger in a world where Naruto also exists. Maybe there are dark forces threatening Luna, and Naruto, with his ninja skills and sense of justice, decides to protect her. He might use his shadow clone jutsu to surround and guard her, or his rasengan to fend off attackers.
The main characters are clearly Luna and Twilight. Luna, being the one who adopts Twilight, is likely to play a guiding and protective role. Twilight, on the other hand, is the one being adopted and will probably experience growth and development under Luna's care.
It could be Naruto himself. Since it's a crossover, he might be the main character who brings his ninja skills and godlike abilities to the MLP world. Maybe he teams up with Twilight Sparkle, and they become the central figures in the story, with Naruto teaching Twilight about chakra and Twilight introducing Naruto to the magic of Equestria.
Naruto might protect a young genin who has shown great potential but has also attracted the attention of a powerful and evil ninja organization. The genin is too young and inexperienced to defend themselves, so Naruto takes on the role of bodyguard. He trains the genin while also keeping them safe from the organization's assassins.
Maybe there are powerful dark sorcerers. These sorcerers could be trying to capture Naruto for their own evil purposes, like using his power to open a portal to a dark dimension or something, and Kurama has to protect him from them.
Perhaps there are some shinobi within the village who are jealous of Naruto's potential. They might try to harm Naruto in secret, and Hiruzen has to be vigilant against them. These shinobi could be from clans that have rivalries with the Uzumaki or those who just don't want a new powerful force emerging in the village.
Obviously, Bella is one of the main characters. And then there must be the members of the pack, though we don't know exactly who they are without reading the fanfiction. There could also be some antagonists, perhaps vampires or other foes who pose a threat to Bella.
Obviously, Jason and Tim are the main characters. Jason is the protector and Tim is the one being protected.
Another possibility is a new and powerful enemy from a neighboring village. This enemy might view fem Naruto as a symbol of the strength of her village and wants to take her out to weaken the village. Shikamaru then has to protect her from this external threat.
It could be Orochimaru. He's always been after power and Naruto's unique abilities would be very appealing to him. So the fem Kyuubi would have to constantly be on guard against Orochimaru's schemes.