One interesting plotline is when the OC aunt has a prophecy related to Harry. She has known about it all her life and has been preparing for the moment when she has to step in and guide Harry. This often involves her having to fight against dark wizards who also know about the prophecy and are trying to stop her from fulfilling her role. Along the way, she teaches Harry new spells and magic that he didn't learn at Hogwarts, which gives him an edge in his battles.
Some fanfics have the plot where the OC aunt is an outcast from the wizarding community for some reason. But she overcomes this when she starts to help Harry. She might have been wrongly accused of a crime in the past. As she helps Harry, she also clears her own name. This makes for a very engaging story as there are two parallel storylines of her redemption and Harry's growth. In addition, there are often sub - plotlines about her making new friends and allies in the wizarding world who initially were skeptical of her.
Maybe the aunt is a half - blood who has a foot in both the Muggle and wizarding worlds. She could be an artist who uses magic in her art, creating paintings that come to life. In fanfiction, she could help Harry see that there are different ways to use magic beyond just spells for combat or everyday tasks, and she could also be a source of comfort during his tough times at Hogwarts.
There could be a fanfiction where Aunt Marge discovers she has some magical ability herself. This would completely change her view of the wizarding world and her relationship with Harry. She might end up joining Harry on some of his adventures, much to everyone's surprise.
One great 'Harry Potter OC Aunt' fanfiction is 'The Aunt from Afar'. It tells the story of an OC aunt who has magical powers and has been in hiding but resurfaces to protect Harry. She has her own unique backstory and her relationship with Harry is really heart - warming.
A common plotline is the characters' post - graduation plans. Some fanfictions might explore how Harry, Hermione, and Ron decide on their career paths. Maybe Harry is conflicted between becoming an Auror or a teacher at Hogwarts. Hermione could be considering further studies in ancient magic, and Ron might be thinking about joining his brothers in the joke shop business. This exploration of their future dreams and how they support each other during this transition period can be really engaging.
One possible plotline could be that Harry is wrongly expelled due to false accusations by a dark wizard who has infiltrated Hogwarts. Harry then has to prove his innocence while on the run from the Ministry. Another plotline might involve Harry being expelled because of a new, strict and unjust headmaster who has a vendetta against him. He could then start his own school for outcast witches and wizards.
Perhaps the snake is a transformed wizard who was cursed. This would lead to a plot where Harry has to find a way to break the curse. He might have to go on a quest to find rare ingredients for a potion. Along the way, he and the snake face various challenges, like dark wizards trying to stop them, and they form a strong friendship through their shared experiences.
One interesting plotline could be where Harry discovers a hidden magic that was lost for centuries. This new magic gives him unique abilities and he has to figure out how to use it without Voldemort finding out. It could change the whole dynamic of the fight against the Dark Lord.
One interesting plotline could be a massive wizarding battleship battle where Hogwarts students and Death Eaters engage in a sea - based fight. The battleship could be enchanted with all sorts of magic, like shields made of Patronus charms.
Another plotline could involve a character jumping into different points in the Harry Potter timeline. They could interact with characters at different ages, like meeting a young Dumbledore and influencing his early views on magic. This would create a whole new set of relationships and story developments. Also, there could be a plot where a character uses the jumpchain to enter the world of Harry Potter from a completely different fictional universe, bringing with them their own set of skills and knowledge which then disrupts or enriches the magical world as we know it.
One interesting plotline could be how Harry's Veela heritage affects his relationships. For example, it might make his interactions with Hermione and Ron more complex as they deal with this new aspect of him. Another could be how his Veela side influences his magical abilities, perhaps giving him an edge in certain spells or magical duels.