Well, a plotline might involve a power - hungry villain who captures Tonks and makes her his slave. This could lead to a story of her resistance from within, trying to undermine the villain's plans while pretending to be compliant. And Harry could be drawn into this situation when he realizes what has happened to Tonks. Or perhaps there's a political plot where Tonks is made a slave as a form of punishment for her family's actions, and Harry gets involved in the political intrigue to free her.
In some fanfictions, the plot could revolve around a new dark force in the wizarding world that institutes slavery for those with certain magical abilities, and Tonks is one of the victims. Her unique metamorphmagus ability might make her a target. Harry, with his sense of justice, then begins a journey to not only free Tonks but also to put an end to this new form of oppression. It could also involve her internal struggle of not losing her identity and hope while being in such a demeaning situation.
A plotline might involve Tonks helping Harry deal with the aftermath of the war. Maybe Harry is suffering from PTSD or something similar, and Tonks' presence in his life helps him heal. As they grow closer, they realize their feelings for each other and decide to get married. There could also be a plot where Tonks is in danger, and Harry risks everything to save her, which then leads to their relationship evolving into a marriage.
It's hard to say for sure as this is not a typical or positive fanfic concept. But perhaps a plotline could be that there is a misunderstanding or a false accusation that leads to Tonks being treated as a slave in some way, and Harry is the only one who believes in her innocence and tries to clear her name and free her. Or maybe there is an ancient magic that has been misused and Tonks is caught in it, making her seem like a slave, and Harry uses his knowledge and courage to reverse the situation. However, we should note that these are all just ideas and this type of fanfic is not what the Harry Potter fandom usually encourages.
There are some fanfictions in this theme. However, the concept of'slave' in this context might be a rather dark and complex exploration within the fan - created world. Some might be found on certain fanfiction websites like FanFiction.net or Archive of Our Own, but it's important to note that not all of them are well - written or adhere to the positive spirit of the original Harry Potter series.
In some 'Snape slave to Harry fanfiction', the plot might start with a prophecy or a magical bargain. Maybe a seer predicted that only with Snape as Harry's servant could a great evil be defeated. So, Snape, bound by this fate, has to follow Harry's commands. Along the way, they face many challenges together. Harry has to deal with the power imbalance and Snape has to struggle with his pride. Their relationship evolves from one of forced servitude to a more complex bond of respect and cooperation as they fight against the forces of darkness.
One interesting plotline could be about Tonks facing the challenges of being pregnant during a time of great turmoil in the wizarding world. Maybe she has to hide her pregnancy to protect herself and the unborn child from the dark forces. Another could be how her relationship with other characters, like Lupin, evolves during her pregnancy, as they deal with the prejudices against werewolves and the danger that surrounds them.
One possible plotline could be Harry realizing his 'slave' status and trying to break free. He might discover some dark secrets about Dumbledore that led to this situation. Another could be Harry being forced to do Dumbledore's bidding in dangerous and unethical tasks, all while struggling with his own sense of self - worth.
One interesting plotline could be Tonks using her Metamorphmagus abilities to help Harry in his undercover missions. For example, she could change her appearance to distract the Death Eaters while Harry sneaks into a place. Another could be Tonks teaching Harry about the less - known magic that her family specializes in.
A possible plot could be centered around Tonks' pregnancy. In fanfiction, it could be explored how she coped with the difficulties during that time, especially considering the dangerous situation in the wizarding world. And how her family supported her.
One plotline could be Naruto being a transfer student at Hogwarts. He might struggle to adapt to the magic system while also showing off his ninja skills. Another could be Naruto teaming up with Harry Potter to fight a common enemy that threatens both the ninja world and the wizarding world.
One possible plotline could be Harry using his knowledge of the wizarding laws, which he learned through his years at Hogwarts and his experiences with the Ministry of Magic, to defend wrongly accused wizards in a wizarding court. Another could be him trying to reform the wizarding legal system which he might find full of loopholes and biases.