Maybe in the fanfiction, Harry's marriage is a political move within the wizarding world. He marries someone from an important pure - blood family to help unite different factions. This could lead to a lot of drama as he has to deal with the politics and also keep his own values intact.
Another plot could be that they are married in an alternate universe where their backstories are different. Maybe Voldemort was never as consumed by dark magic from the start. Harry and Voldemort could then discover that they have a deeper connection than they thought, and their marriage could be a journey of self - discovery for both of them, as they explore their relationship in a world that is both familiar and yet very different from the one they knew in the original story.
One idea could be that they start a new magical school together. Since Gabrielle has her own magical abilities and Harry has so much knowledge from his Hogwarts days, they combine their resources to create a school that focuses on both traditional and unique magical teachings.
One idea could be them exploring different magical creatures together as a married couple. They might go on a journey to find a rare and endangered magical creature and work towards its conservation.
One idea could be that they face challenges from the wizarding community who don't understand their relationship. Another could be them exploring new magical abilities together as a married couple. Maybe they could also go on adventures to discover ancient magic secrets that are related to their combined family lineages.
One plot idea could be a time - travel fanfiction where they get married in an alternate timeline. Maybe Harry accidentally activates a time - turning device and ends up in a world where he, Ginny and Hermione all decide to have a triple wedding for some magical reason. Another could be a post - war fanfiction where they get married as a symbol of new beginnings and unity among the wizarding community. For example, their weddings could be grand events that bring together all the different houses and factions that were once divided during the war.
Another plot could involve the main character in the fanfiction realizing that they got married too young and now they are having second thoughts. This could lead to a series of self - discovery and relationship - testing events. For example, they might meet someone new who makes them question their marriage, but in the end, they realize the value of their relationship.
One idea could be that it's a magical accident due to a misfired spell. Maybe Harry was trying to help someone with a fertility spell and it backfired on him. Another could be that it's part of some ancient prophecy where a male must carry a child for a great purpose. And perhaps there's a new type of magic that allows male pregnancy and Harry is the first to experience it in the wizarding world.
In some fanfiction, Harry might get married in a secret ceremony to protect his family from a new threat. His friends would be the only ones in on the secret. The wedding could take place in a hidden location, like an ancient, enchanted forest. His wife could be a powerful witch who has her own secrets. Their marriage could be a key part of a bigger plan to defeat an emerging evil. There could be a lot of mystery and intrigue surrounding their relationship, with them having to keep their true feelings and intentions hidden from the outside world.
They could start a magical school of their own. As a married couple, they would pool their resources and knowledge. Hermione's love for learning and Harry's practical experience would make for a great curriculum. They would face opposition from the traditional wizarding schools at first, but eventually prove that their new way of teaching magic is beneficial for young wizards and witches.
One idea could be them having to deal with the reactions of their friends and family. For example, Harry's friends from Gryffindor might be initially shocked but then come to accept it as they see how happy Draco and Harry are together. Another plot could involve them facing some sort of magical mystery or threat that only their combined skills can solve, which also strengthens their bond as a married couple.