Temari and Kankuro, Gaara's siblings, are likely to be in the fanfiction as well. They could play protective roles towards their little sister, or they might have some conflicts with her as she tries to assert her own identity. And there could be some antagonists, like rogue ninjas from other villages who see Gaara's sister as a target for some reason.
There could be original characters created specifically for the fanfiction. For example, a magical creature that befriends Natsu's little sister and helps her on her journey. But the core Fairy Tail characters usually play important roles as well. They are the ones who provide the familiar backdrop of the Fairy Tail world that the story is set in.
Obviously, Gohan and his sister are common characters. Goku might also be there as their father. Vegeta could be included too, as he is often part of the Dragon Ball storylines. Maybe Piccolo as well, since he has a connection to Gohan.
Hisoka's sister's friends or allies she makes along the way would also be common characters. They could be other up - and - coming Hunters or just ordinary people with special abilities. These characters help her in her adventures, whether it's in a fight or in solving a mystery. Another character that might appear is Ging, as he has a connection to the Hunter world and could potentially cross paths with Hisoka's sister in some way.
There could be other minor characters from Forks that get more spotlight in these fanfictions. For instance, the classmates of Bella's little sister who start to notice that there's something strange about her. They might become curious and start to dig deeper into the secrets of the town, which then draws in the vampires and werewolves.
Naruto is often paired with Gaara in these fanfictions. Their strong bond in the original series makes it interesting to see how they interact when Gaara time - travels. Naruto could be the one to help Gaara adjust to a new time period or vice versa.
Often, Naruto's female characters are paired with Gaara. For example, Hinata. Since Hinata is a kind - hearted and shy character, her relationship with the initially cold - hearted Gaara could be an interesting exploration of how two different personalities come together.
The Weasley family would probably play a role too. Ginny could be a role model for the little sister, especially in terms of being a strong female witch. Fred and George might teach her some of their pranks or tricks. And Mrs. Weasley could be like a second mother to her, showing her the warmth of a family. The Malfoys could also be in the story, perhaps as antagonists, creating conflict for the little sister and Harry.
One interesting plot could be that Gaara's little sister has a special power that she has to keep hidden from the village at first. This creates a lot of mystery and tension as she tries to navigate her life without being discovered.
Often, there are the victims or potential victims of Jeff. They might be ordinary people in the neighborhood who start to notice strange things going on and suspect Jeff. Another common character could be a detective or a police officer who is trying to solve the mystery of the killings and might eventually cross paths with the little sister.
The most common character is Gaara as it's his story of being a baby daddy. The mother of the baby is another crucial character. Depending on the plot, other characters from the Naruto world could be included. Shikamaru, being one of Gaara's acquaintances, could show up to offer his strategic advice on how to handle fatherhood. Kankuro and Temari, his siblings, might also be there to provide family support or add some family - related drama to the story. And the baby, which is at the heart of the 'baby daddy' concept, would be a central element in the interactions of all these characters.