A great scenario in a Ginny and Harry get married fanfic would be a destination wedding in a far - flung magical place. Maybe they choose a wizarding island where they can have the ceremony on the beach under a starlit sky filled with magical constellations. Another scenario could be that they get married in a rebuilt Hogwarts, with the castle being a symbol of their past and their future together. And then there could be a scenario where Ginny and Harry have a very modern - wizarding wedding, with new spells and charms being used for the decorations and entertainment that no one has seen before.
One possible scenario could be that Harry finally finds the courage during a quiet moment at Hogwarts, perhaps in the Gryffindor common room by the fireplace. He might stutter a bit at first, but then clearly say his feelings. Another could be that it happens during a dangerous adventure when he realizes he can't hold his feelings in any longer, fearing he might lose Ginny. Maybe he confesses after Ginny has been in some sort of danger and he realizes how much she means to him.
One possible scenario could be that Ginny and Harry are in the Gryffindor common room. Ginny has had a long day of Quidditch practice and studying. She sits next to Harry on the couch, and as they are chatting softly about their day, her eyes start to droop. Harry notices but doesn't want to disturb her, and soon she falls asleep on his shoulder. Harry then just sits there, feeling a warm sense of protectiveness and contentment.
One possible scenario could be that they are in the Gryffindor common room. The fire is crackling, and everyone else has gone to bed. Harry and Ginny sit on the couch, and slowly start to get closer. Their eyes meet, and then they share a gentle kiss that gradually becomes more passionate as they let their feelings for each other take over.
In a Ginny and Harry get married fanfic, there could be some interesting plot twists. Maybe some dark forces try to disrupt the wedding at the last moment, but Harry and Ginny's love and the power of their friends' magic overcomes it. Their wedding could also be a big gathering of the wizarding world, with old friends and new allies coming together. The exchange of vows would be a very emotional moment, showing how far they've come from being just friends to being soulmates.
One possible plot could be a detailed account of their wedding day. It might start with Ginny waking up, feeling a mix of excitement and nervousness. Harry could be shown getting ready with Ron and Hermione by his side, sharing some old memories. The ceremony could be a grand affair with all their friends and family from Hogwarts present. There could be a magical display during the vows, perhaps some floating candles and enchanted flowers. After the wedding, they could have a reception filled with dancing and laughter, and then they might go on a honeymoon to a secret, magical location.
One possible scenario could be that Ginny meets an old acquaintance who has changed a great deal and she starts to have feelings for this person while still being with Harry. Maybe they share a common interest that she feels Harry doesn't understand. However, this goes against Ginny's strong character in the original series, so it's a very different take in fanfiction.
In some versions, it could be that Harry has to die to break a dark curse placed on Ginny. He discovers that his life is the key to saving her and willingly gives it up. He might have a premonition about Ginny's fate and decides that his death is the only way to change it. He then confronts the source of the curse and allows it to take his life instead of Ginny's.
One possible scenario could be Sirius noticing how Harry blushes whenever Ginny's name is mentioned. So he might say something like, 'Harry, I've seen you go redder than a Weasley's hair at the mention of Ginny.' Another could be if Ginny gives Harry a special gift, and Sirius teases him about it, 'Harry, that little present from Ginny must mean something special, eh?' A third scenario could be when Ginny is around and Harry acts a bit clumsy. Sirius would then joke, 'Harry, you're more out of sorts than a drunk Hippogriff when Ginny's near.'
In some fanfictions, there might be a scenario where Harry and Ginny get engaged during a dangerous adventure. They could be on a mission to defeat a new dark wizard, and in a moment of calm before the final battle, Harry realizes that he doesn't want to face anything else without Ginny by his side, so he proposes. Or perhaps it happens during a celebration at Hogwarts. After a big victory for the school, like winning the House Cup, Harry takes Ginny to the Astronomy Tower and asks her to marry him. There could also be a situation where Ginny is the one who takes the lead. She might plan a special date and then propose to Harry, showing her strong and independent character.
In some fanfictions, they might go on adventures together. Exploring the wizarding world more fully, perhaps seeking out new magical creatures or ancient magic. They have a thirst for discovery after the chaos of the war. Harry's knowledge and Ginny's courage would make them a great team on these excursions.