Well, it could be about Tonks having a special moment with the character she hugs. Maybe she discovers something important during this hug. For example, she could be hugging Harry Potter to comfort him after a difficult battle, and through this hug, Harry realizes he has more support than he thought.
In this fanfic, the hug could be a turning point in Tonks' relationship with another character. If we consider the 'mine' as a metaphorical place of danger or self - discovery, Tonks might be hugging someone (maybe Harry) to convey her feelings of trust. It could also be that they find something valuable in the mine, and the hug is a celebration of their discovery.
Tonks might be hugging Remus Lupin. Since they have a romantic relationship in the Harry Potter series, a hug could be a way to show their affection, and the 'mine' could be part of an adventure they share together.
In a fanfic, it could be a scenario where Tonks has been secretly admiring Harry for his bravery. One day, Harry accomplishes something really great and Tonks, overjoyed, yells'mine' in a sense of pride, like he's part of her group of heroic people she admires, and hugs him tightly. For example, when Harry manages to defeat a powerful dark wizard on his own.
In this fanfic, it could start with Tonks using her Metamorphmagus abilities to secretly help Harry in some dangerous situations. Harry becomes intrigued by this mysterious helper. As they finally meet face - to - face, there's an instant connection. They then embark on a journey together to solve a new mystery in the wizarding world. Along the way, their relationship deepens, and they get married. Their marriage could be a symbol of a new era in the wizarding world, where different kinds of relationships are accepted and celebrated, and they also work together to bring about positive changes in the magical society.
A simple fanfic could have Tonks and Harry on a mission together. When Harry is about to be attacked, Tonks jumps in, yells'mine' to the attacker as a warning that Harry is under her protection, and then hugs Harry to make sure he's okay. This shows Tonks' loyalty and her fierce protectiveness over Harry.
One possible plot could be that Tonks accidentally creates a potion that makes her swap appearances with Harry. This would lead to a series of comical and confusing situations. For example, Tonks (in Harry's body) has to deal with Harry's friends not realizing it's her, and she has to figure out how to reverse the effect while also not getting Harry into trouble at Hogwarts. Meanwhile, Harry (in Tonks' body) has to navigate the world of the Order of the Phoenix and deal with Tonks' responsibilities.
Yes, there are likely some fanfics out there with this premise. Fanfiction websites are full of creative takes on different pairings in the Harry Potter universe. You can try searching on popular fanfic platforms like Archive of Our Own or Fanfiction.net.
Perhaps a plot twist could be related to memory modification. One of them has their memory modified in the past which affects their relationship in the present. For instance, Tonks might have had her memory modified by some dark magic and she forgets her previous relationship with Harry and Hermione. As they try to restore her memory, they discover secrets about their past together and it changes the course of their marriage.
Well, if such a fanfic were to exist, it could be a humorous take on an awkward situation. Maybe Harry and Tonks are on a secret mission and have to hide in a small space that just happens to have a bath, and they end up having to share it to avoid being detected.
It could also show how Tonks and Lupin deal with the stress of the situation. They are in the middle of a war, and having a baby is a big deal. Maybe they struggle to find a safe place for their family. Lupin, being a werewolf, might be worried about how his condition could affect their child. And Tonks, being a member of the Order, might feel torn between her duties and her pregnancy.
One common theme is the forbidden love aspect. Given their age difference and Tonks' relationship with Lupin in the original series, it creates a sense of something that shouldn't be but is. Another theme is the idea of them finding solace in each other during the dark times of the wizarding war. Harry is often burdened with so much, and Tonks, with her own struggles, can offer him a different kind of support and vice versa.