Another way they could interact is through magical research. Maybe Fleur is interested in some of the spells Harry used during the war, and she approaches him to learn more. This could lead to a series of meetings where they exchange knowledge and gradually become closer as they discover more about each other's magical abilities and interests.
In some fanfictions, their interaction could be more casual. They could meet at social gatherings in the wizarding world. Harry would be the famous hero, and Tonks would be the friendly Auror. They could share a laugh, talk about the latest Quidditch matches or new spells that have been developed. It would be a normal, friendly interaction between two people who know each other.
Often, in fanfiction Harry and Ginny are central to the social group. After the war, they could be involved in group activities like Quidditch matches where they play together or watch as spectators. They would cheer for their friends, and their presence would bring a sense of unity. Their relationship would also be a model for some of their friends. For example, Ron and Hermione might look to them for relationship advice, and they would happily offer their insights based on their own experiences.
Fleur could use her Veela charm to try and disarm or distract vampires. Since Veela have a certain allure, it might work on vampires as well.
Well, they might interact with mutual respect. Naruto, being the hero of the war, would earn Anko's respect. And Naruto, who respects all his comrades, would value Anko's skills. They could exchange stories about their war experiences over a meal in the village.
Often, Naruto would show great respect to Tsunade. He might visit her regularly to check on her and discuss village matters. Tsunade, in turn, would be proud of Naruto's growth and might give him more responsibilities within the village.
They might interact through joint missions. For example, if there are tasks related to helping the wounded or rebuilding areas damaged during the war, they could work side by side. Naruto's strength and Shizune's medical skills would complement each other well.
They could interact with a great deal of suspicion at first. Hermione would be cautious around Bellatrix, not fully trusting her motives. Bellatrix, on the other hand, might be trying to prove that she has changed. For example, Bellatrix could offer Hermione some rare magical books as a peace offering, but Hermione would be hesitant to accept.
There could be a scenario where Snape is initially hesitant to interact with Hermione. But she is persistent. She tries to understand his past and his pain. As she breaks through his walls, they start to have a more open and honest communication. They might exchange stories about their time at Hogwarts during different eras, and Snape could finally have someone who truly understands him, at least to some extent, in Hermione.
They may interact through training sessions. Naruto could be interested in learning more about Tenten's weapon - using skills, while Tenten might want to understand Naruto's chakra control better. So they exchange knowledge during their training.
Fleur and Tonks might start off a bit wary of each other. Fleur, with her proud and somewhat haughty nature, could see Tonks as a bit too brash. But as they both love Harry, they would have to find common ground. They could start sharing stories about Harry's heroic deeds from their different perspectives. Eventually, they would become friends and support each other in the relationship with Harry.