Perhaps the Shadows Sword has the power to reveal secrets. In the fanfiction, Silena could be on a quest to understand her own family's past, and the sword is the key. Harry Potter gets involved because he realizes that the secrets the sword can uncover might also be related to the overall safety of Hogwarts. So they team up, with Harry using his knowledge of Hogwarts' secrets and Silena using her new - found knowledge of the Shadows Sword, to explore the mystery.
If there was some sort of danger associated with the Shadows Sword, Harry Potter would immediately take on a protective role. He would try to keep Silena safe while also trying to figure out what the sword is all about. Silena would not be one to just stand back and let Harry do all the work. She would want to be involved in every step of the investigation. This could lead to some small arguments between them as they both have strong opinions on how to handle the situation with the Shadows Sword.
Well, one interesting idea could be exploring the backstories of minor characters in more depth. For example, the house - elves' lives and their own magic that is not fully explored in the original books. Another idea might be alternate endings to major events, like what if Voldemort had won the Battle of Hogwarts? It could also involve creating new spells or magical creatures unique to the fanfiction world.
A possible plot could involve a time - traveling aspect. The Sword of Truth travels through time and lands in the Harry Potter era. It has a prophecy attached to it that only a true Gryffindor can wield it to save the wizarding world from a new, impending doom. Harry, being a Gryffindor, is naturally drawn to it, but he has to face many challenges and self - doubts before he can fully accept the power of the sword and use it to defeat the new threat which could be an ancient dark magic that has been awakened.
One idea could be Norberta getting lost in the Forbidden Forest and Harry has to find her. Another could be Norberta growing ill and Harry, with his knowledge of magical creatures, tries to heal her. Maybe Norberta could get into trouble with some other magical creatures and Harry has to step in to protect her.
One idea could be a story where a character has a special power to resist Dementors' effects more than others. Maybe they discover a hidden spell or have a unique magical ability that they use to fight off Dementors when others are in danger. For example, a young witch or wizard who can emit a positive energy that counteracts the Dementors' despair.
Perhaps Orochi is a hidden figure in the history of the wizarding world that has been forgotten. Harry discovers some old texts in the Hogwarts library that mention Orochi in relation to a long - lost magical artifact. This leads him and his friends on a quest to find the artifact before it falls into the wrong hands, as it has the power to either control Orochi or be used by Orochi to gain ultimate power over the wizarding world.
One idea could be that the scarecrow comes to life and becomes a magical creature that helps Harry Potter in a dangerous task. Maybe it has the ability to sense dark magic and warns Harry of approaching threats.
One plot idea could be that Harry and Angelina team up for a special Quidditch training session for the younger students. They discover a new flying technique together that gives Gryffindor an edge in future matches. Another could be that they go on a secret mission within Hogwarts to uncover a hidden artifact that has been causing strange magical disturbances. And a third idea is that Angelina gets injured during a match and Harry uses some of his unique magical skills, learned from his various adventures, to help her recover faster than normal.
One plot idea could be that Silena and Percy team up on a secret mission in the mortal world. They have to blend in and solve a mystery that's threatening the demigod world while also dealing with their own personal differences. Maybe Silena's skills in charm speak and Percy's water powers complement each other in unexpected ways during the mission.
Another plot idea is to create a parallel universe where the rules of the 'game of shadows' are slightly different. This could lead to new alliances and conflicts among the characters.