Ron could be a side character. He might be hovering around, giving unwanted advice to both Harry and Ginny, since he is also a big fan of wizard chess. Hermione could also be there, rolling her eyes at Ron's antics and making some intelligent comments about the strategies Harry and Ginny are using. Maybe Neville could pop in too, just to watch the game and cheer them on in his own shy way.
The Weasley twins could be side characters. They might show up and try to add some mischief to the game. For example, they could use some of their magical prank items to make the chess pieces do funny things. Luna Lovegood could also be a side character. She might be sitting nearby, making some dreamy and off - the - wall comments about the significance of the chess moves in relation to the cosmos or something equally Luna - like.
Well, perhaps the plot could be about Harry and Ginny having a friendly chess match. During the game, they might be chatting and joking around, reminiscing about old Hogwarts days. Ginny could be using some really clever strategies she learned from the Weasley family's long - time love for wizard chess. Harry, on the other hand, might be relying on his quick thinking skills that he developed while facing various challenges at Hogwarts.
Ron and Hermione could be main characters. They are Harry and Ginny's closest friends. Hermione might offer her vast knowledge of magic to help with any problems the baby has, like if there are some strange magical symptoms. Ron could be there for comical relief, making jokes about how Harry has become a proper family man now.
Definitely include Fred and George. Their mischievous nature can create some light - hearted moments in the otherwise tense fifth year. They could also help Harry and Ginny in some sneaky ways, like getting around Umbridge's rules. Seamus and Dean could be good side characters as well. Their different reactions to the events in the fifth year, especially with the rising threat of Voldemort, can show the diversity of the student body at Hogwarts.
Obviously, Harry would be an important character even though he leaves. His actions before leaving and potential return would greatly affect the story. Also, the Weasley family, especially Ginny's mother Molly. Molly would probably be very involved, offering her motherly advice and support. Ron and Hermione might also be involved. Ron as Ginny's brother would surely have an opinion and Hermione could be there for Ginny as a friend.
The remaining Death Eaters could be the antagonists. Even though Voldemort is gone, there could be some who still hold a grudge against Harry and want to finish what their master started. They might track Harry and Ginny down as they run away, creating dangerous situations for the couple.
Neville could play an interesting role. Maybe he could be the one who discovers a new magical plant that is needed for a potion to cure an illness that Ginny or Harry contracts during their marriage. Luna could also be involved. She might come to them with some strange but useful prophecies that help them in a difficult situation, like dealing with a dark wizard who has a grudge against Harry even after the war is over.
The obvious target audience would be Harry Potter fans, especially those who are interested in the relationship between Ginny and Harry. They would enjoy reading about Ginny expressing her feelings for Harry in the form of singing, as it adds a creative and unique aspect to their relationship.
Neville could also be a godparent. He has proven himself to be a brave and reliable wizard. After all his growth throughout the series, he could be a great influence on Harry and Ginny's first child, teaching them about the importance of perseverance and believing in oneself.
Ginny herself would obviously be a main character, even as a baby. Then Harry, Ron, and Hermione are likely to be main characters as well. They are her friends and would be the ones most likely to try and solve the problem of her being turned into a baby. They would be involved in taking care of her and finding a way to reverse the transformation.
Hermione would definitely be one. She might give Ginny some wise advice about dealing with Harry, like how to handle his sometimes - clueless behavior. She could also help Ginny with her studies so she doesn't have to worry too much about that and can focus on the Yule Ball.