They could potentially be colleagues. Since they are both part of the wizarding community, they might work together in some capacity. For example, Tonks could be involved in Auror training and Harry, with his combat experience, could assist. Their relationship could be based on mutual respect for each other's skills and contributions to the post - war wizarding society.
Another possibility is that they might just have an occasional acquaintance - like relationship. Harry has his own circle of friends like Ron and Hermione, and Tonks has her own family and friends. After the war, they might cross paths from time to time, exchange pleasantries, but not be overly involved in each other's lives.
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.
In some fanfictions, they could become close friends. After the war, they both have gone through a lot, and they might bond over their shared experiences. Harry could be there for Tonks as she recovers from the traumas of the war, and Tonks, with her kind heart, could offer Harry the warmth of a true friend.
There are also fanfictions where Harry and Fleur have a more complex relationship. Harry might develop a sort of mentorship towards Fleur's future children, given his own experiences. Fleur, in turn, could be a source of comfort for Harry during his post - war struggles with PTSD. Their relationship could be one of mutual support and understanding, evolving over time as they both move on from the traumas of the war.
In some fanfictions, they might become friends. After the war, they could realize that the old rivalries were pointless. Harry, being the forgiving person he is, might reach out to Pansy, and she, having seen the error of her ways, could accept his friendship. They could then work together to rebuild the wizarding world.
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.
Some fanfictions might depict them as having a more adventurous post - war life. They could be involved in rebuilding the wizarding world in a more hands - on way. Harry might use his fame and Ginny her popularity among the younger wizards to bring about positive changes. Their relationship would be based on mutual respect and a shared goal of making the wizarding world a better place.
They could become very close friends. After the war, they both have a shared understanding of the trauma and changes they've been through. They might support each other in rebuilding their lives at Hogwarts or in the wizarding world in general.
In certain fanfictions, Harry could be the one to reach out to Snape. He might feel a sense of indebtedness towards Snape for his sacrifices. Snape, initially resistant, could eventually warm up to Harry's attempts at reconciliation. This could lead to a very different dynamic from their pre - war relationship, with them learning from each other and forging a new path in the post - war wizarding world.
After the war, Harry and Ginny's relationship in fanfiction could be centered around family. They might start thinking about having their own family soon. Ginny would want to create a warm and loving home environment, different from the often cold and lonely upbringing Harry had. Harry, on the other hand, would be eager to be part of a real family. They would also be surrounded by their friends, like Ron and Hermione, and together they would form a tight - knit community in the wizarding world.
In some fanfictions, they might become closer friends than ever. After the war, they've shared so much trauma and victory that their bond deepens into a platonic relationship where they support each other through post - war rebuilding and dealing with their respective emotional scars.
In some fanfictions, Harry might come to understand Snape better and they could develop a grudging respect for each other. Harry realizes all that Snape sacrificed in the war and how he was on the good side all along.