Chiron could play a significant role. He has a wealth of knowledge and experience, and could offer advice on both the pregnancy itself and the potential future of the child. Thalia could also be a great supporting character. She and Annabeth have a long - standing friendship, and Thalia's tough - love attitude could be just what Annabeth needs sometimes, especially when she's feeling down or worried about the pregnancy.
Tyrion Lannister could be a great supporting character. His intelligence and political acumen could be useful in protecting Daenerys during her pregnancy. He might also offer some witty remarks and advice regarding the situation. Another could be Missandei, as she is Daenerys' loyal handmaiden. She could provide emotional support and help with practical matters, like preparing for the baby.
Melissa's sister could be a great supporting character. She could offer advice based on her own experiences with pregnancy and motherhood. Maybe she helps Melissa with baby shopping and gives her tips on dealing with morning sickness.
Leafpool could be a main supporting character. As Squirrelflight's sister, she could offer her medical knowledge and emotional support during the pregnancy. Bramblestar would also be important. As Squirrelflight's mate, he could be there to protect her and help with preparing for the kits.
Another possibility is that it could be a god in disguise. Given the complex relationships between demigods and gods in the Percy Jackson universe, a god could have fallen in love with Annabeth and fathered her child. This would bring all sorts of divine drama and complications to the fanfic.
Most likely, Percy could be the father. They have a strong relationship in the original series, so it would be a natural choice. Their chemistry and shared adventures could be the basis for a story where they start a family together.
Sasuke's mother could be an interesting supporting character. She could share stories of Sasuke when he was a baby with Sakura, which would make Sakura feel more connected to Sasuke and the family. And Kakashi could also be there. He might offer some wisdom and calm reassurance during Sakura's pregnancy journey, just like he has always been a guiding figure for his students.
The main characters are most likely Annabeth and Percy. Since Annabeth is the one who is pregnant, she would be a central figure. And Percy, being her partner, would play a crucial role in protecting her and the unborn child in Tartarus.
Fitz and Simmons would be interesting. They could use their scientific knowledge to monitor Daisy's pregnancy and the baby's health, especially considering Daisy's unique situation with her powers. They might also create some special devices to help her during pregnancy, like something to dampen her powers if they become too much to handle.
Ashley could be a good support. She has a strong personality and could help Emma stand up to any bullies or negative comments. And then there's Marco. He's very empathetic and could be there for Emma when she has doubts or fears. He might even help her pick out baby clothes or decorate the nursery, showing his support in a practical and fun way.
Bellatrix could be an interesting supporting character. She is Narcissa's sister, and her extreme views and loyalty to Voldemort could create some tension. For example, she might try to influence Narcissa's unborn child's future in a way that Narcissa doesn't like. Another good character could be Dobby. He could be secretly helping Narcissa with small tasks during her pregnancy, despite being a house - elf and the Malfoys' former servant.