Well, it could be about the students at Hogwarts in the Harry Potter universe learning about demigods. Maybe they discover the existence of demigods from Greek or Roman mythology and how their powers and worldviews differ from wizards and witches. It might involve some sort of cultural exchange within the fictional realm, like sharing magic and skills.
Maybe some new characters from the demigod side could also be main characters. For example, a demigod like Percy Jackson could be introduced to the Hogwarts world. And of course, Dumbledore would also play an important role as he guides the students in Hogwarts and would be involved in any new discovery like learning about demigods.
It could be a fanfic where characters interact with demigods and ask them various things. Maybe it involves a story where mortals or other beings get to pose questions to demigods, like about their powers or their adventures in the mythological world.
It could be about Harry Potter learning some long - forgotten or lost magical arts. Maybe he discovers ancient spells, potion - making techniques that have been lost for centuries, or unique forms of divination that are no longer practiced in the wizarding world.
It might be a story where Harry delves into the family magic in order to solve some sort of mystery. For example, he could be looking for a way to defeat a new dark force and realizes that the family magic holds the key. He could learn new forms of magic related to protection or divination that are unique to his family.
The 'harry learns the old ways fanfic' is likely centered around Harry's exploration of archaic knowledge or practices. It could be that he discovers an old library filled with dusty tomes that hold the secrets of the old ways. As he reads and learns from these, he might start to incorporate these old ways into his daily life in Hogwarts or his battles against the dark forces. He could learn things like how wizards used to communicate without wands, or ancient forms of defensive magic that have been long forgotten by most in the modern wizarding world.
One common theme is discovery. Harry discovers his magic in unexpected ways, like finding a hidden magical object or meeting a mysterious figure. Another theme is secrecy. Since he's not supposed to use magic outside of Hogwarts yet, he has to keep his newfound skills a secret from the Dursleys.
He might be more confident. Since he already has some knowledge of runes, he can participate more actively in classes related to ancient magic or spells. For instance, in a runes class, he could answer questions quickly and gain the respect of his peers and teachers.
The 'harry learns both sides of the force fanfic' might be a story where Harry is thrust into a situation where he discovers the duality of the Force. It could show his journey as he tries to understand the good and bad aspects of this powerful energy. For example, he might meet characters from the Star Wars universe who teach him about the Force, and he then uses this knowledge in his own battles or moral dilemmas back in the wizarding world.
There's a fanfiction called 'Early Magic for Harry'. In this story, Harry stumbles upon an old magic book in the cupboard under the stairs. This book helps him start learning magic even before he gets the Hogwarts letter. He begins with simple levitation spells and gradually progresses. It's a really interesting take on how Harry could have been more prepared for Hogwarts if he had known some magic beforehand.