Maybe they are involved in a mystery at Hogwarts. Since they are both connected to the school in different ways. They could be investigating some strange happenings that seem to be related to an old dark magic that was once thought to be buried. This would test their relationship as they have to rely on each other's strengths and deal with the potential danger.
A plot could involve Harry and Ginny going on a magical honeymoon to a far - off, little - known wizarding location. Along the way, they encounter strange magical creatures and have to use their combined skills to survive and make it to their destination. Also, they could decide to start a family, and the story could focus on their experiences during Ginny's pregnancy, like the funny and heartwarming moments of preparing for the baby.
A possible plot is that there's a mysterious illness spreading among the Quidditch players, and Harry and Ginny have to figure out what's causing it and how to stop it before the big Quidditch tournament. Or perhaps a new and dangerous Quidditch move is introduced by a visiting team, and Harry and Ginny must learn it quickly to stay competitive. They could also have a friendly rivalry with another couple who are also big Quidditch fans.
Perhaps there's a magical guitar that Harry and Ginny find. It has special powers, like when Ginny plays it, it can calm the most ferocious magical creatures. They go on a journey to figure out the origin of the guitar and along the way, their relationship deepens as they face various challenges together.
One idea could be that Harry and Ginny are swimming in a secret pool at Hogwarts that has some magical properties. Maybe the pool can change its shape or temperature based on their emotions. Another could be that they are having a swimming race to train for a Triwizard Tournament - like event for adults. And they use magic to enhance their swimming abilities in creative ways.
One plot idea could be that Hermione and Ginny team up to play a prank on Harry, but it backfires in a hilarious way. For example, they try to make his hair turn purple but instead it starts changing colors every few seconds. Another idea is that the three of them go on a secret adventure outside of Hogwarts to find a lost magical artifact. They face various challenges and their friendship is tested. And perhaps a plot where Hermione discovers a new spell that accidentally causes some chaos between Ginny and Harry's relationship, and she has to find a way to fix it.
One idea could be exploring their wedding planning and all the chaos that comes with it. Maybe Molly Weasley is over - involved and wants everything to be perfect, while Ginny just wants a simple ceremony. Another could be their first year of marriage, dealing with things like living together in a new home and adjusting to each other's habits.
In a 'Harry Marries Ginny' fanfiction, a great plot could be about them starting a family. It could detail Ginny's pregnancy, Harry's concerns and excitement, and how they prepare for the arrival of their baby. It could also include the reactions of their friends and family. This would be a heart - warming story that shows their growth as individuals and as a couple.
One idea could be that Harry returns from a long and dangerous mission. Ginny has been worried sick. When they reunite, there's an immediate rush of emotions. They hug tightly and Ginny scolds Harry a bit for making her worry, but it's all out of love. Another could be they reunite at Hogwarts during an anniversary event. They see each other across the Great Hall and slowly make their way towards one another, with memories of their school days flooding back.
Perhaps Teddy gets into trouble at Hogwarts, and Harry and Ginny have to step in to sort things out. It could involve Teddy being wrongly accused of something, and they use their skills and influence to clear his name. Or Teddy discovers a secret room in Hogwarts that only he can access, and he enlists Harry and Ginny to explore it with him.
One idea could be how Harry and Ginny prepare for the baby, like choosing names. Another might be Ginny's experience with the physical changes during pregnancy. Maybe there could be a plot where they face some threats while Ginny is pregnant and Harry has to protect her and their unborn child.
One plot idea could be that Harry and Ginny discover they are Animagus during their time at Hogwarts and use their forms to secretly explore the Forbidden Forest. Their Animagus forms might give them an advantage in finding hidden magical creatures or ancient magic that could help in the fight against Voldemort.