In some fanfictions, the Black Dragon Emperor might have a special relationship with Harry Potter himself. It could be a mentor - like relationship, teaching Harry some ancient and powerful magic that was long forgotten in the wizarding world. This would give Harry an edge in his battles against the forces of evil and also introduce a whole new aspect of magic to the story.
Perhaps a plotline where the Black Dragon Emperor has to form alliances in a world that is both fearful and envious of his power. He could encounter different races and factions, each with their own motives for allying or opposing him.
One interesting plotline could be a dragon becoming a secret ally to Harry Potter. It might help him in a dangerous mission by providing aerial support or using its fiery breath to fend off dark creatures.
One possible plotline could be Harry secretly raising the dragon in the Forbidden Forest. He might have to find ways to feed it without being caught. Another could be that the dragon helps Harry in a battle against Voldemort's forces, using its firepower and strength.
Well, there are many. For example, a plotline might center around a dragon duelist who is wrongly accused of using illegal spells during a duel. They then have to clear their name while also preparing for an important upcoming duel. Another could be a story where a young girl discovers she has a special power that allows her to communicate with dragons during duels, giving her an edge. This power, however, attracts the wrong kind of attention from some dark wizards. Also, a plot could be about a dragon - dueling club in Hogwarts that is on the verge of being shut down due to some mysterious accidents during duels, and the members have to find out what's really going on to save their club.
A plotline could be that the dragon is actually a guardian of a long - lost magical artifact hidden deep within Gringotts. A brave adventurer tries to befriend the dragon to gain access to the artifact. The dragon tests the adventurer's worthiness throughout their encounters.
One interesting plotline could be a dragon family protecting Harry Potter from a new dark threat. The dragons, with their fierce loyalty and powerful magic, could form an unexpected alliance with Harry and his friends. For example, the dragon family might have a special connection to an ancient magic that Voldemort is seeking, and they must keep it out of his hands.
Perhaps a plot where Orion Black and Harry Potter team up to fight against a new dark threat in the wizarding world. Orion's experience and Harry's unique skills could make for an exciting adventure.
One interesting plotline could be the exploration of the Black sisters' relationships before and during the events of the Harry Potter series. For example, how Bellatrix's loyalty to Voldemort affected her relationships with Narcissa and Andromeda. Another could be a story where the sisters have to team up to protect a family secret related to the Black family heritage. Maybe a plot where they interact with Harry Potter in a way that wasn't shown in the original books, like helping him uncover some dark magic that has a connection to the Black family.
One interesting plotline could be a secret mission to uncover a hidden dark magic artifact that the Ministry of Magic has been covering up. The characters might have to use their stealth and unique skills to navigate through dangerous areas.
One common plotline is Sirius Black escaping from Azkaban earlier and secretly training Harry in advanced magic. Another could be Sirius and Harry going on a hidden adventure to uncover more about Harry's parents. There are also stories where Sirius plays a more active role in the fight against Voldemort at Hogwarts, using his knowledge of the Dark Arts and his Animagus form to their advantage.