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 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.
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.
One of the main characters would likely be Lupin. Since he has a connection with Tonks, his presence could add a lot of drama to the story. He might suspect their relationship or even accidentally discover it. Another could be Hermione. She's always observant and might pick up on the signs of their relationship, and could either support them or be concerned about the implications. Ron could also be in the mix, perhaps being a bit clueless at first but then getting involved in some way.
In some fanfictions, they might become very close friends. After the war, they both have endured a great deal. Harry could rely on Tonks' experience and her unique perspective. Tonks, on the other hand, might see Harry as a symbol of hope and a comrade who has fought bravely. They could support each other in rebuilding the wizarding world, sharing their stories and helping those who were affected by the war.
Their relationship could become even stronger. After surviving the war together, they would have a deeper understanding and appreciation for each other. They might become more affectionate and open with each other, having seen the worst and still being there for one another.