In some fanfictions, the blue fire could have magical properties that are different from normal fire. It could be used to heal wounds or even travel through time. A story could revolve around a character who gets injured and is healed by the blue fire, but then discovers it has unforeseen consequences on the timeline.
There might be a fanfiction where the blue fire is a symbol of a secret society within Hogwarts. The members use the blue fire to mark their meetings and protect their secrets. Harry and his friends stumble upon this society and have to decide whether to join or expose them.
One interesting 'Harry Potter Blue Fire' fanfiction could be about a new spell that creates blue fire and how it's used in a battle against the Dark Arts. For example, a young wizard discovers this spell in an ancient tome and has to learn to control it quickly when Voldemort's forces attack Hogwarts.
Another fanfiction might involve the Blue Scarab being part of a prophecy. It could be that the scarab's appearance signals a great change in the wizarding world. Maybe it is related to a new form of magic that Harry and his friends need to learn about in order to save Hogwarts from a new, unknown threat that is more powerful than Voldemort ever was.
One interesting 'Harry Potter White Fire' fanfiction could be one where the White Fire is a new magical element discovered in the Forbidden Forest. It might have unique powers that Harry and his friends have to learn to control to save Hogwarts from a new dark threat.
One interesting 'Harry Potter Fire Lord' fanfiction could be one where the Fire Lord's powers are incorporated into the wizarding world in a unique way. For example, the Fire Lord's ability to control fire might be combined with a Harry Potter character's magic, creating new spells or defenses. Another could involve a crossover where the Fire Lord is transported to Hogwarts and has to adapt to the magical school environment, causing all sorts of chaos and new friendships or rivalries.
There are fanfictions where Fem Harry's character development is more focused on her femininity. In the Goblet of Fire setting, she might deal with the added pressure of looking 'proper' for the Yule Ball. Some fanfictions explore how she uses her intelligence and female charm to get through the tasks in the tournament. For instance, she might use her wits in a different way than the original Harry to outsmart the dragons.
One interesting fanfiction could be about the aftermath in the graveyard. Maybe it focuses on how Harry copes with what happened there, like him having nightmares and his friends trying to comfort him. It could also explore the mystery of the dark magic residue left in the graveyard.
One interesting fanfiction could be about an alternate take on Harry's experience in the Triwizard Tournament. Maybe it focuses on his relationships with the other champions in a way that wasn't fully explored in the original book. For example, a deeper bond between Harry and Cedric.
One interesting fanfiction could be about a character's rage over being wrongly entered into the Triwizard Tournament. Maybe they feel like they've been set up and their rage fuels their actions throughout the tournament, leading to unexpected twists in the tasks.
One interesting fanfiction could be where Harry's anger at being entered in the Triwizard Tournament against his will leads him to discover a hidden plot much earlier. He might start to suspect that someone within Hogwarts is working against him and begins his own investigation. This could involve him using his skills in a more unorthodox way, like using the Marauder's Map to track the movements of the teachers and other suspicious characters.
One interesting Harry Potter 1945 fanfiction could be about the early days of Hogwarts and how the magical world was different back then. Maybe it focuses on the founding of certain magical traditions that we see in the main series but are not fully explored. For example, it could detail how the houses were originally established and what the selection criteria were like in 1945.
One interesting 'Harry Potter Lord Potter' fanfiction could be the ones where Harry discovers his true heritage as 'Lord Potter' much earlier and starts to reshape the wizarding world's politics. It often involves him being more assertive and using his family's ancient powers and influence.