One interesting plotline could be how they deal with the challenges of their different personalities. Harry is often seen as serious and determined, while Tonks is more carefree and fun - loving. Their marriage might involve a lot of humorous misunderstandings at first as they learn to live together. For example, Tonks might play pranks on Harry that he initially doesn't take well but then learns to enjoy.
One possible plotline could be Harry and Tonks teaming up with the members of the harem to face a new dark wizard threat. They might use their combined magical abilities and unique relationships to outwit the enemy.
One possible plotline could be how Harry and Tonks navigate their different personalities. Harry is often seen as serious and determined, while Tonks is more carefree and fun - loving. Their relationship might start with some misunderstandings due to these differences but then grow into a deep understanding and love. Another plotline could involve how they deal with the wizarding world's reaction to their union, as it's quite an unexpected pairing. Some might oppose it, while others might see it as a new beginning for the wizarding community.
One interesting plotline could be Harry and Tonks teaming up for a secret mission in the wizarding world that was not part of the original story. Maybe they have to infiltrate a dark wizard's lair.
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.
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.
Well, a plotline might involve Tonks using her Metamorphmagus abilities to secretly meet Harry in different disguises. This adds an element of mystery and fun to their relationship. They could also be sharing secrets about their past traumas, like Harry's experiences with Voldemort and Tonks' insecurities, which deepens their bond on a more emotional level. Maybe there's a sub - plot where they have to keep their relationship from Tonks' family, especially her Auror colleagues who might not approve.
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.
In this fanfiction, a plotline could center around the cultural differences between Fleur (being part - Veela) and Tonks (a Metamorphmagus). Harry would have to navigate these differences as they raise their children together. There could also be a plotline about the training and upbringing of the children, as they are likely to be very powerful with Harry as their father, and how this will shape the wizarding world in the future.
One idea could be the cultural and family clashes that come with such a contract. Maybe Harry's friends are shocked and have mixed reactions. Another could be how Harry and Tonks grow to understand and care for each other in the context of this contract. For example, they start off as strangers in this arranged - like situation but gradually find common interests.
One interesting plotline could be Tonks trying to fit into the complex and often dark Black family traditions while still maintaining her own identity. She might struggle with the family's views on blood purity and her own more inclusive beliefs.