Nathan's older sibling might play an important role. They could be the voice of reason for Nathan, helping him understand the responsibilities of becoming a father and guiding him on how to support Max through the pregnancy.
Max's best friend could be a great supporting character. She could offer emotional support to Max during the pregnancy, give her advice on how to deal with Nathan, and be there for her when she's feeling scared or uncertain.
Perhaps in the fanfiction, Nathan and Max are in a world where they are part of a special group or have unique powers. Their pregnancy could be a result of some kind of magical or extraordinary event. They then have to deal with not only the pregnancy but also protecting their unborn child from those who might want to use its potential powers.
They could have friends like Lily and Tom. Lily might be Karen's best friend who is always there to give advice on pregnancy, like what kind of maternity clothes to buy. Tom could be Nathan's friend from work who offers to help with any DIY projects for the baby's room.
One potential supporting character could be the Hogwarts professors. They may have different reactions to Harry's situation. Some might be more accepting and try to help, like Professor McGonagall who could use her Transfiguration skills to create things that are useful for Harry during his pregnancy. There could also be some characters from the Asgardian side, like Heimdall, who could be observing the situation from afar and may or may not choose to interfere depending on how he sees the future implications.
Haley would be a great supporting role. She could offer Peyton advice on pregnancy based on her own experiences. Lucas could also be included, perhaps he helps Nathan with getting ready for the baby, like fixing up a room in their house. And Brooke, she might be the one to throw a baby shower for Peyton and bring in all the fun and glamour to the story.
Snow White and David are often main supporting characters. They are Emma's parents, so they would be there to support her during the pregnancy. They might offer advice on parenting and how to deal with the challenges that come with it.
Definitely his family members. His mother, for example, would be a crucial supporting character. She would be worried sick about him and would do everything in her power to take care of him. His father might also play a role, perhaps using his godly powers in some way to ease Percy's suffering.
One of the likely supporting characters is Tsunade. Given her experience and leadership in the village, she could be a source of advice for Naruto and Hinata. She might also ensure that Hinata has the best medical resources available during her pregnancy. Rock Lee could be another supporting character. His positive attitude and loyalty to Naruto would make him eager to help out. He could be running errands for them or helping with any physical tasks. And Neji, if he were still alive in this fanfiction, would surely be there to protect his cousin Hinata and support Naruto as well.
Ino could be one of the main supporting characters. She might help Hinata with choosing baby names or decorating the nursery. Shikamaru, on the other hand, could offer some practical advice on how to deal with the changes in life that come with having a baby. And of course, Hinata's family members like her father and sister would also play important roles in supporting her during this time.
Edward would be an obvious choice as a main supporting character. He would be there for Bella, sharing in her joys and fears, and helping with all the preparations for the twins. Another could be Alice. She might use her ability to foresee things to help Bella prepare for any challenges during the pregnancy.
Their parents could be the main supporting characters. Bridget's mother could share her own experiences of pregnancy and motherhood, while Eric's father could offer practical advice on how to handle the new responsibilities. Also, a neighbor who has children of her own could be a great support. She could give them hand - me - downs, and offer babysitting tips and tricks.