Obviously Ranma herself. Her father Genma could also be a major character as he has to deal with his daughter's new permanent state. Akane could be there too, and their relationship would likely be very different. Instead of the typical boy - girl rivalry, it could turn into a more complex female - female dynamic.
There could be new characters introduced. Maybe some girls who become Ranma's friends and help her navigate her new life as a girl. Also, some of the antagonists from the original story might interact with Ranma in different ways now that she's a girl. For example, Kodachi could see her as either a new rival or a potential ally in the world of female - dominated activities.
Ryoga could also play an interesting role. He might be confused by Ranma's new appearance at first, but then develop a different kind of relationship with her. And don't forget about Shampoo and Ukyo. Shampoo might see Ranma as a threat in a different way now, and Ukyo could try to support Ranma in her new identity while still having her own feelings for her.
Well, it could be about Ranma having to adjust to life as a girl permanently. Maybe she has to deal with new social situations, like how her friends and family now see her in a different light. She might also explore new hobbies or interests that are more typical for girls in that fictional world.
Ranma is the key character, of course. But characters like Shampoo and Ukyo might also be deeply involved. Shampoo might see Ranma as a rival in a different way now, or perhaps try to befriend her more sincerely. Ukyo could also have a change in her feelings towards Ranma, either becoming more protective or having a more complex emotional struggle. And don't forget about the various martial arts masters who might interact with Ranma differently because of her new gender.
In addition to the main ones, characters like Shampoo and Ukyo might play important roles. Shampoo, who has her own feelings for Ranma, may have a different approach to a female - Ranma. Ukyo too, might have a new dynamic with Ranma in this situation. And of course, there could be other minor characters from the original series that get involved in the fanfiction, depending on the author's creativity.
Obviously, Ranma and Akane are prime candidates. Their relationship is central to the series, so a pregnancy between them would create a lot of drama and interesting storylines. Shampoo could also be involved in some way. Maybe she's jealous and tries to interfere, or she could be surprisingly helpful. Genma, Ranma's father, would also play a role. He might have some old - fashioned or comical ideas about the situation.
Obviously, Aria herself is the main character. Her family members like her mother and father could be important characters, offering support or having different opinions. Her best friends would also be likely to be involved, providing emotional support or getting into some friendly arguments about how she should handle the pregnancy.
Well, there could be her best friend who is always there for her during the pregnancy, giving her advice and emotional support. There might also be a mysterious figure, like an old wise woman who has knowledge about pregnancies in special circumstances that Tera Faya's case might be. And of course, there could be a rival of some sort, who might try to use her pregnancy against her in some way.
Igneel could also play a role. Since Igneel was Natsu's adoptive dragon father, he could appear in Natsu's mind during the transformation, guiding him and giving him advice on how to handle his new dragon powers. And there could be other dragons in the story as well. They might be either friendly or hostile towards Natsu depending on their nature.
There could also be new characters introduced. Maybe other magizoologists from different parts of the wizarding world. They could have different approaches and beliefs about magical creatures. Some might be rivals, trying to outdo Harry in the discovery and study of new species, while others could be mentors, guiding him in the complex world of magizoology.
The Avengers could be involved. Captain America, for instance, might be suspicious of this 'Loki' (who is actually Harry) and keep a close eye on him. Iron Man could use his technology to analyze Harry, thinking he is Loki. And from the Harry Potter universe, Ron could be there, trying to support Harry in this strange situation where he is mistaken for someone else entirely.
Definitely the Naruko clone herself. Then there could be Sasuke. He might be intrigued by the clone and try to understand her existence. Also, Kakashi could be involved, maybe as a mentor figure to the clone, guiding her. As for the 'lemon' side, there could be some random attractive ninja from another village who catches the clone's eye and they develop a romantic relationship.