Well, perhaps the fanfiction could start with Harry finding an old family heirloom or a mysterious spell that transforms him into Warlock Black. Then, he might have to keep this a secret from his friends at first. As the story progresses, he could find that being Warlock Black gives him access to ancient magic that the Dark Lord is also after. So he has to race against Voldemort to master this magic and use it for good. Also, his relationships with the members of the Black family, both the good and the bad ones, could be a major part of the plot.
A possible plotline in this fanfiction could be that Harry is somehow magically transformed into Warlock Black against his will. He then has to figure out how to reverse it while also dealing with the consequences of this new identity. He might be shunned by some in the wizarding world who fear the Black name, but at the same time, he could find allies within the family who help him. The story could also involve Harry using his new status to uncover secrets about the Black family that are crucial in the fight against Voldemort. For example, he could discover a powerful spell or a hidden weapon that only a Warlock Black can access.
One possible plotline could be that Harry discovers he has a hidden connection to the Black family that makes him Lord Black. This could lead to him having new powers or responsibilities within the wizarding world, and he might have to deal with the complex politics and family secrets of the Blacks.
Perhaps the Black family member is in danger, and the betrothal is a way to protect her. Harry gets involved in the Black family's secrets and power struggles while trying to uphold the betrothal. Another plot could be that it was a magical accident or a prophecy that led to the betrothal, and they have to figure out how to deal with it.
Perhaps a plotline where Sirius Black discovers a hidden prophecy related to Harry Potter that requires Harry to submit to Sirius in a series of magical trials. These trials could be designed to unlock Harry's true potential. Or it could be a plotline where the wizarding world is in chaos, and Sirius, with his knowledge and experience, convinces Harry that submitting to his leadership is the only way to restore order. This could involve Harry following Sirius' orders in battles, in diplomatic relations with other magical creatures, and in reforming the Ministry of Magic.
Perhaps in this fanfiction, the magic of the Harry Potter universe and the technology/vibranium of Wakanda are somehow intertwined. For example, the Deathly Hallows could have a connection to Wakandan artifacts. Harry could find himself in Wakanda and be mistaken for a threat at first. But as he proves his good intentions, he and Black Panther could start to exchange knowledge. They could then use their combined powers and knowledge to stop a dark force that is trying to steal Wakandan resources and use them to gain power over the wizarding world.
A plotline could involve Black Canary being a mysterious figure who appears in the Forbidden Forest. Harry and his friends are initially suspicious but soon realize she has powers and knowledge that can help them. In terms of the 'lemon' element, it could be that Black Canary has a past connection to a character's family. For example, she was once in love with a wizard from an old family in the Harry Potter world. This connection resurfaces and causes a stir in the wizarding community, while they also have to deal with threats from Voldemort's remaining followers who are intrigued by this new arrival.
One possible plotline could be that Casetopia Black is a powerful wizard from a far - off land. He arrives at Hogwarts and challenges Harry Potter to a magical duel to prove his worth. This duel could lead to a new friendship or rivalry between them.
One possible plotline could be that Harry has done something dangerous in the wizarding world, like sneaking into the Forbidden Forest without permission. Sirius, as his godfather, decides to give him a mild spanking as a form of discipline while also explaining why his actions were wrong and how they could have put him in great danger.
One possible plotline could be that Bellatrix is somehow brainwashed or redeemed early on. Harry, seeing the potential for good in her, tries to help her further. Over time, they develop feelings for each other and end up getting married. Another could be a time - travel scenario where Harry goes back in time and changes Bellatrix's path before she becomes a full - fledged Death Eater, leading to their relationship and marriage.
One possible plotline could be that Melania is a new student at Hogwarts who has a connection to the Black family. Maybe she discovers a long - lost Black family secret that could change the wizarding world. For example, it could be a powerful spell or a hidden treasure. Another idea is that she gets involved in a mystery related to the Black family's dark past and has to team up with some of the well - known Harry Potter characters like Harry, Hermione, or Ron to solve it.
One possible plotline could be Harry discovers his latent archmage powers early on and uses them to quickly defeat Voldemort. Another could be that he has to go on a journey to learn how to fully control his archmage abilities while still dealing with the normal Hogwarts stuff like classes and friendships.