In the fanfiction, it could be that Jaune found the pet Grimm when it was just a baby. He took it in and raised it, but as it grows, it starts to attract the attention of more powerful Grimm. Jaune then has to find a way to protect his pet and himself from these threats while also dealing with the moral implications of having a Grimm as a pet.
Well, perhaps the plot could involve Jaune trying to train the pet Grimm. He might face challenges from other characters who are against having a Grimm as a pet due to their inherently dangerous nature.
Maybe there are other Grimm that see the pet Grimm as an outcast for being with a human. These Grimm could come after the pet and Jaune, making them the antagonists. They would try to either kill the pet and bring it back to the Grimm world or kill both Jaune and his pet to keep their world 'pure'.
One idea could be that the female Grimm is an outcast among her kind. Jaune, with his sense of justice, tries to understand her instead of immediately fighting. They form an unlikely alliance and learn from each other, with Jaune teaching her about the value of life and she showing him the secrets of the Grimm world in return.
One possible plot could be that Jaune discovers his pet wolf has special powers. For example, the wolf can communicate telepathically with Jaune. They go on adventures together, using the wolf's powers to solve mysteries or defeat enemies in their world.
One possible plot could be that Jaune discovers he has a daughter in a very unexpected way. Maybe she shows up at Beacon Academy one day, and he has to figure out how she came to be. He then has to balance his duties as a Huntsman with being a father, all while protecting her from the various threats in the RWBY world.
One possible plot could be that Naruto is somehow transported to the RWBY universe and takes on the role of Jaune. He then uses his ninja skills to help Jaune's team in battles and they are all amazed by his abilities.
Another plot could be that the Grimm mask was once a part of an ancient weapon or a powerful relic. Ruby discovers it and realizes that it has a connection to the origin of Grimm. As she delves deeper into the mystery of the mask, she uncovers long - forgotten knowledge about the creation of Grimm and how to potentially stop them for good.
In this fanfiction, it might start with Jaune as a baby being found by the dragon. As he grows, the dragon imparts its wisdom on him, like ancient languages or secrets of the land. Jaune could also have a special bond with the dragon that allows them to communicate telepathically. His journey could be about finding his place in the world, whether it's among the dragons or with the humans. He might also discover that he has a special mission, something that only he, with his unique upbringing, can achieve.
In a fanfic like this, there could be a lot of conflict. The Grimm's presence could be seen as a threat by the Hidden Villages. Naruto would then have to convince everyone that his pet Grimm is not a danger. Also, the Grimm might have special abilities that Naruto could use in battles or to solve problems in the village. For example, if the Grimm can fly, Naruto could use it to quickly reach far - off places or spy on enemies. And Naruto could also teach the Grimm some of his ninja values, like loyalty and perseverance.
In this fanfiction, perhaps Izuku's pet is a magical being. It could be that the pet was sent to Izuku by some mysterious force to help him on his journey to become a great hero. The pet might be able to sense danger and warn Izuku in time. As Izuku grows closer to the pet, he discovers more about its past and the secrets it holds. This relationship could also attract the attention of villains who want to use the pet's power for their own evil purposes, leading to some intense battles and rescues.
It could be that Jaune has some sort of traumatic past experience with funus, which makes him scared. Maybe he witnessed its destructive power or had a personal encounter that left him with deep - seated fear.