Another scenario might be a situation where they are reminiscing about old times. They are sitting by the fireplace in the Gryffindor common room, and Ginny sits on Harry's lap as they talk about their adventures at Hogwarts, from fighting Voldemort to their first encounters with magical creatures. This would be a very sentimental moment for them.
It could also be a moment of affection during a celebration. For instance, after Gryffindor wins a Quidditch match. Ginny, being excited and proud, jumps on Harry's lap in the middle of the celebration in the common room. They would be laughing, sharing the joy of the victory, and perhaps stealing a quick kiss or two.
Perhaps in a parallel universe where the whole wizarding world is different. There are no enmities between the Slytherins and Gryffindors from the start. Draco and Harry are friends, and Draco sitting on Harry's lap could be a common occurrence during their friendly banter or while sharing secrets in a cozy corner of the Hogwarts library. It could be a sign of their deep - seated friendship and trust.
Maybe they are sitting by the Black Lake. They could be discussing their experiences in the wizarding world. Harry might be talking about his fight against Voldemort, and Luna would be offering her unique, otherworldly perspectives, perhaps comparing Voldemort to some dark magical entity she's heard of in old tales.
It can be a sign of their growing intimacy. In a relationship, such actions are often markers of a deeper level of closeness. It might also make their relationship more public within the Hogwarts community, as others would see this display of affection.
Maybe they go to a wizarding cottage in the countryside. They explore the nearby magical forests together, discover new magical creatures, and Ginny could teach Harry some new Quidditch tricks in the large open fields around the cottage. And of course, they have cozy evenings inside, cooking together and snuggling up by the fireplace.
One possible scenario could be that they are on a long journey and there is limited seating space, so Annabeth simply sits on Percy's lap for convenience. Maybe they are on a boat and there are not enough benches.
In some fanfictions, it might occur during a trip on the Hogwarts Express. They are sitting in a compartment, just the two of them. The train is chugging along, and the scenery outside is passing by. Harry looks at Ginny and starts a conversation about their future. Then he casually asks if she would like to go on a date with him when they get back to Hogwarts. It could also be after Ginny has been in some sort of danger. Harry is so relieved when she's okay that he blurts out his feelings and asks her out.
One possible scenario could be them renovating their home at the Burrow. They might be adding new rooms for their future family. Ginny could be using her magic to make the place more cozy while Harry helps with the physical labor, like moving furniture with a levitation charm.
Another possibility is that they would take a stroll in the moonlight around their new home. They would hold hands and reminisce about their adventures at Hogwarts. Harry might tell Ginny how much he loves her all over again, and Ginny would respond with sweet kisses, and then they would go back inside to have a warm drink and cuddle by the fireplace.
They might get married and start a family right away. In fanfiction, it's common to see them settling down and having kids, living a peaceful life after all the chaos of the battle.
One possible scenario could be that they have a peaceful family life. They might raise their children in the wizarding world, teaching them about magic and the values of love and courage. Harry could be involved in the Ministry of Magic, perhaps working on improving the safety and equality in the wizarding community. Ginny, on the other hand, might continue her career as a Quidditch player or become a Quidditch coach, passing on her skills and passion for the sport.