One possible interesting plotline could be the Rose Child having unique magical abilities that are different from the regular magic in the Harry Potter world. For example, they might be able to communicate with a special kind of magical creature that others can't.
Perhaps the Rose Child has a connection to an ancient magic that was long forgotten in the wizarding world. This could lead to a series of adventures where they have to discover the secrets of this magic and how it can be used to either save or endanger the wizarding community. They might find clues in old, dusty tomes in the Hogwarts library or from the memories of very old wizards and witches.
Well, perhaps the child in the 'Harry Potter child in Azkaban' fanfiction forms unexpected alliances. Maybe they team up with some of the inmates who have their own reasons to oppose the unjust system of Azkaban. This could lead to a series of adventures where they try to break free from Azkaban's clutches together.
Perhaps a plotline where Harry discovers other immortal beings. He could form a sort of community with them, learning about different cultures and powers that immortality has bestowed upon them. They might teach him how to better control his immortality, like hiding his true nature from mortals or using his extended lifespan to gain knowledge that no one else has. This could lead to adventures as they try to protect their secret from those who would seek to exploit it.
One possible plotline could be the discovery of the secret child and how it affects Harry's relationships with his friends and family. For example, Hermione and Ron might be shocked at first but then become supportive. Another could be the challenges the child faces growing up in the wizarding world with this secret hanging over them.
In some Harry and Ginny Cursed Child fanfictions, the plot could revolve around their children. Ginny might notice some strange behavior in their kids that she suspects is related to the Cursed Child's influence. She then teams up with Harry to investigate. They could find out that there are some latent magical powers in their children that are being affected by the dark magic from the Cursed Child's events. This could lead to a series of challenges and adventures as they try to help their children and safeguard the wizarding world.
In some 'Harry and Draco secret child fanfiction', there could be a plotline where the child serves as a bridge between the two families. Harry's side, like the Weasleys, and Draco's family might initially be against the idea of the child. But as the story progresses, the child's presence changes their perspectives. The child might also struggle with its own identity, being part wizard from two very different backgrounds, and this internal struggle could be a central part of the story.
Well, some might involve magical creatures with furry characteristics in new adventures at Hogwarts. For example, a werewolf character could have a unique story arc that intersects with the main Harry Potter plot. Maybe they are trying to find a cure or dealing with the prejudice within the wizarding world in a different way than what's in the original books.
One possible plotline could be a comical take on baby Harry's magical mishaps. Maybe he accidentally makes his diapers levitate or turns his crib into a mini Hogwarts. Another could be about how the other characters like Hagrid or Dumbledore interact with baby Harry in this unique situation, perhaps trying to figure out how to handle his early magical outbursts while he's still in diapers.
Perhaps a plotline where the ogre has some sort of special power that the wizards in Harry Potter are interested in. This could lead to a whole series of events where they try to either control or cooperate with the ogre.
In some fanfiction, a familiar might get lost in a different dimension. So, the main character has to go on a journey to find it. Along the way, they meet strange new creatures and learn new spells, which is really exciting. It also shows a different side of the bond between a wizard and their familiar.
There could also be a fanfiction where a member of the Sacred 28 discovers a long - lost family secret that has the potential to change the power dynamics among the pure - blood families. This secret could be related to a hidden magic or a forgotten alliance, and as they try to uncover more about it, they face opposition from other families who fear the change it might bring.