One possible fanfiction could be about Dipper and younger Wendy going on a mystery-solving adventure in the woods. Maybe they discover a hidden fairy glade that no one else in Gravity Falls has ever found. They have to work together to figure out the secrets of the glade, and in the process, their friendship deepens.
Some common themes in Wendy fanfiction are friendship and growth. Wendy often forms strong bonds with other characters, and these relationships help her to grow as a person. For example, she might learn important lessons about loyalty and trust through her interactions with friends. Additionally, themes of family can be present. Wendy's family might play an important role in the story, either as a source of support or as a catalyst for change in her life.
As time passes, Wendy might start to feel a sense of responsibility towards the Lost Boys. Even though she was kidnapped, she realizes they are just lost children. So, she could start to take on a motherly role, teaching them manners and telling them stories. This would be her way of making the best of a bad situation and also showing her kind heart.
One popular character paired with Wendy in fanfiction is Peter Pan. Their connection in the original tale makes it natural for fanfiction writers to build on their relationship. It could be a story of them growing up together or facing new challenges side by side. Also, Hook can be paired with Wendy in some fanfiction. This creates a rather unique and unexpected dynamic, perhaps a story where Wendy tries to redeem Hook or they form an unlikely alliance against a common enemy.
Wendy might initially be very frightened. After all, being kidnapped by a fearsome pirate like Captain Hook is a terrifying situation. She could be trembling and trying to hold back her tears.
Wendy could start as a naive character, believing in the good of Peter Pan as in the original story. But as she discovers his evil side, she quickly has to grow up and become more cynical. For example, she might become more distrustful of those around her, always looking for signs of deception.
Wendy would probably be surprised at first. After all, Natsu's greetings are often unexpected. But then she would be really happy, with a big smile on her face. She might blush a little too, since it's such a special and personal greeting from Natsu.
She could look for any weaknesses in Bill's lair or the place where she is being held. Maybe there is a loose board she can use to break free or a hidden passageway. Also, if she has any special skills or powers, like being able to communicate with animals, she could use them to call for help or create a distraction to escape.
One possible motive could be that Bill has some sort of vendetta against Wendy. Maybe she has something he wants, like a powerful object or information that could give him an edge in his evil plans. Another reason could be that he wants to use her as a bargaining chip against someone else, perhaps a hero or another character who has been thwarting his plans.
I'm not entirely sure if there is a specific 'Naruto father of Wendy Marvell' fanfiction. There are countless fanfictions out there, and while crossovers between Naruto and Fairy Tail are popular, it would take some searching through fanfiction websites to know for sure. It could be a really unique and interesting concept, as Naruto's ninja abilities and Wendy's dragon slayer magic could create some cool storylines if combined in such a family - like relationship.