Well, it could be about hidden alchemical knowledge within the wizarding world. Maybe it reveals how certain potions are related to alchemy in a deeper way than we knew from the original books.
The secrets might involve the connection between alchemy and magic spells. For example, some spells could be based on alchemical principles. In the fanfic, it could show that the way wizards manipulate magic has roots in alchemical practices that were long forgotten. It might also explore how alchemy is related to the magical creatures in the Harry Potter universe. For instance, how the properties of a phoenix or a basilisk could be linked to alchemical substances.
One secret could be about the true nature of certain magical artifacts that were only hinted at in the original books. For example, the Marauder's Map might have deeper secrets like how it was enchanted to show not just the castle but also hidden passages that lead to other magical realms.
One of the secrets could be about hidden relationships between characters. For example, a secret friendship that was never shown in the original books but explored in the fanfiction.
Hermione Granger might also be a main character. Given her thirst for knowledge and her skills in magic and research, she would be very interested in the secrets of alchemy. She could be the one who discovers clues and tries to piece together the alchemical mysteries. Ron Weasley could also be involved. Maybe his loyalty and courage are needed to help Harry and Hermione in their quest to uncover the secrets, and he might provide some comical relief during their adventures related to the alchemy secrets as well.
One possible secret could be about Naruto's real parents' untold past. Maybe there are hidden details about how his father and mother met that were not in the original story.
There could be a secret chamber in Hogwarts that no one has found yet in fanfic. This chamber might hold ancient magic or the key to a powerful spell. It could be hidden by powerful enchantments and only a select few characters, perhaps those with a special connection to the founders of Hogwarts, might be able to discover it.
Maybe it uncovers that there are other forms of magic that were lost over time but are now being rediscovered in the fanfic. Such as a type of magic that allows wizards to communicate with magical creatures on a deeper level, not just the basic interactions we saw in the books.
Well, one secret could be about the true origin of a certain character. Maybe in the fanfiction, it reveals that a side character has a much more important family lineage than was previously thought in the official Star Wars lore. For example, they might be related to a powerful Jedi or Sith from the past.
One family secret story was about a hidden inheritance. A family had an old attic that no one really bothered with. But when they finally decided to clean it out, they found a box full of old letters and a deed to a small property that had been forgotten for generations. Turns out their great - grandfather had bought it but never told anyone. Another story is of a family that discovered they had a famous relative. A young girl was doing some genealogy research and found out that her great - aunt was a silent movie star. It was a huge shock as the family had no idea about this part of their history.
There may be a dark secret about a character's family in fanfic. For example, Harry Potter might discover that his parents had a dark side or were involved in something very dangerous before they died. This could completely change his perception of his family and add a new layer of complexity to his character.
In Harry Potter fanfic, one travel secret could be the use of hidden Portkeys in unexpected places. For example, a seemingly ordinary pebble on a deserted beach might be a Portkey to a magical location only known to a select few in the fanfic. Another could be secret passages within the Forbidden Forest that lead to different parts of the wizarding world, like a hidden village of magical creatures.