Typically, there is the human female character who becomes the mother. She might be an ordinary woman who suddenly finds herself in this extraordinary situation. Then there is the alien male character, the 'baby daddy'. He could be from a technologically advanced alien race or a more primitive one, depending on the story.
There are often secondary characters like friends or family of the human female. They might be supportive, or they could be against the relationship and the idea of having an alien baby. For example, a protective brother who is worried about his sister's well - being. Also, there could be other aliens who are either allies or enemies related to the baby daddy, adding more complexity to the story.
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.
In Naruto fanfiction, characters like Jiraiya could also be a 'baby daddy'. He was known for his womanizing ways in the series, so it's not hard to fathom a situation where he has a child. Then there's Itachi. Although his life was full of tragedy and secrecy, a fanfiction could explore a scenario where he has a child before his untimely death. And Kiba could be a character as well. His close bond with his dog Akamaru and his brash personality could lead to a situation where he becomes a 'baby daddy' in a creative fanfiction.
Edward Cullen is one of the most common baby daddies in Twilight baby daddy fanfiction. Since he's the main male lead in the original series and has a complex relationship with Bella, it's natural that many fanfiction writers explore the idea of him as a father. Jacob Black is also a popular choice. His relationship with Bella was also significant, and in some fanfictions, he could end up being the baby daddy in an alternate storyline. Another character who might be the baby daddy in some fanfictions is Aro from the Volturi. His powerful and mysterious nature makes for an interesting take on being a father in the Twilight - inspired stories.
One interesting concept could be the unique cultural clashes between the human and alien species in terms of raising a baby. For example, the alien might have very different ideas about discipline or education compared to humans.
There could also be side characters like the baby daddy's friends or family members. His best friend might be trying to convince him to either step up or run away from his responsibilities. Or his mother could be a traditional figure who has very specific ideas about how he should handle the situation, adding more conflict to the story.
Obviously, Danny Phantom himself could be the 'baby daddy'. His dual nature as a human and a ghost could bring a lot of interesting twists to the story of having a baby. For instance, the baby might inherit some of his ghost powers, which would create all kinds of challenges for raising the child.
Sirius Black is a very common 'daddy' character. In the original story, he was Harry's godfather, so it's easy to expand on that relationship in fanfiction. He has the potential to be a loving and protective figure for Harry.
Ben and Josh are the central figures. Ben could be portrayed as the more impulsive of the two. He might make hasty decisions that often get them into funny or tricky situations. Josh is probably the one who tries to keep things in order. He's the one who thinks about the consequences and tries to guide Ben in a more responsible direction. Their relationship is what drives the fanfiction forward.
Riley and Danny are the main characters. Riley might be a character with a mysterious past that slowly unfolds throughout the story. Danny may have a strong family background that influences his actions towards the baby. And the mother of the baby is also a crucial character as her relationship with both Riley and Danny drives the story forward.
The baby daddy is obviously one of the main characters. He's the one whose journey and growth are often central to the story. Then there's usually the mother of the baby, who has her own role in the relationship dynamic.