You can develop her through her goals and dreams. Maybe she wants to continue her parents' legacy in some way. As she pursues this, she faces obstacles that force her to grow. Her character can also be developed by her reactions to different situations, whether it's a dangerous encounter or a happy celebration.
To develop the character of Tails and Cosmo's daughter, consider her appearance as well. Does she have physical traits from both parents? This can influence how others perceive her and how she perceives herself. Her skills and abilities should also evolve over the course of the fanfiction. Start with her basic skills inherited from her parents and then show how she hones them or discovers new ones through her experiences.
First, give her a distinct personality. For example, she could be curious like Tails but also have Cosmo's calmness. Then, show her relationships with other characters. Her bond with her parents can be explored, like how they teach her their skills. Also, her interactions with friends or foes can develop her character.
One way to develop their characters is to put them in challenging moral dilemmas. For example, they might have to choose between saving a group of endangered plants (important to Cosmo) or stopping a mechanical menace (more in Tails' area of expertise). Through these situations, they would have to reevaluate their values and grow as characters. Also, Cosmo could learn to be more assertive in the face of danger, and Tails could become more adaptable to new and unexpected situations.
They would become more protective of each other. Tails would be constantly looking out for Cosmo during her pregnancy, making sure she's comfortable and has everything she needs. Cosmo would also be more dependent on Tails, and their bond would strengthen as they are about to become parents.
She can be developed by giving her unique personality traits. For example, if she has her father's intelligence but also a more outgoing nature. This contrast would make her interesting. Also, showing her relationship with other characters like Harry Potter or Hermione Granger can develop her. If she has a friendship or a rivalry with them, it would show different sides of her.
Another plot could involve the daughter going on a journey to learn more about her parents' past. Along the way, she meets different characters who knew Tails and Cosmo. This journey of self - discovery also helps her to understand her own place in the world and her unique abilities.
To develop the baby nine - tails, it could be given a unique personality trait such as being very empathetic. So, it can not only feel Naruto's emotions but also those of other villagers. This causes it to try and bridge the gap between Naruto and the villagers who fear it. It might go out of its way to show the villagers that it means no harm, which in turn would make for an interesting character arc as it tries to change the perception of the nine - tails in the village.
Explore her relationships. She could have a complex relationship with Salem, loving her mother but hating her actions. And with the RWBY characters, she could start as an enemy but gradually become an ally. By developing these relationships, her character can become more multi - dimensional. For example, her friendship with Blake could start with distrust but grow into a strong bond as they share their stories of being different from their families.
Her character can be developed through her relationships. For example, her relationship with Edward can show her loyalty and love for her father. If she has friends, how she interacts with them can show her kindness or shyness.
Tails and Cosmo's wedding was a magical affair. The meadow was filled with colorful flowers. Tails was nervously waiting at the altar. Cosmo walked down the aisle in a beautiful white dress made of the softest petals. Their friends were all there, Sonic with a big grin, Knuckles looking a bit shy. As they said their vows, the wind gently blew, as if nature itself was blessing their union.
You can start by giving her a distinct personality. For example, if she's more like Tony, she could be humorous and quick - witted. If she takes after Ziva, she might be more serious and focused. Then, give her some goals or dreams. Maybe she wants to follow in her parents' footsteps but in a different way, like using modern technology to solve crimes. Also, show her relationships with other characters, such as her grandparents or her parents' friends.
To develop their daughter in a fanfiction, first, think about her appearance. Does she have Ash's eyes or Serena's hair? Personality - wise, she could be shy at first but as she gets into Pokémon adventures, she becomes more confident like her father. Also, her relationships with other characters are important. Maybe she has a rival who challenges her in ways that help her become stronger both as a trainer and as a person.