In some goblin debt fanfics, the plot might revolve around how the goblin debt affects the wizarding economy. For example, if Harry's debt is so large that it starts to influence the value of Galleons. The goblins could use this debt as leverage to gain more control over Gringotts' operations in relation to the wizarding world. Harry then has to find a way to break free from this economic stranglehold.
One idea could be that the main character, perhaps Harry himself, befriends a goblin who has a secret knowledge about a hidden magical artifact. This could lead them on an adventure to find it before the wrong hands do. Another plot could involve a goblin friend helping Harry understand the complex and often unfair goblin - wizard relations in the wizarding world. Maybe the goblin has a personal vendetta against some wizards who have wronged his family and Harry gets involved in helping him seek justice.
A great plot could be that the goblin is a time - traveler. It has come from a future where Voldemort has won and is trying to change the past. The goblin teams up with Harry, using its unique goblin magic and knowledge of the future to give Harry an edge in the fight against the dark forces. They might have to travel to different magical locations and enlist the help of other magical creatures.
A really interesting plot could be that a goblin mate has a unique magical ability that is the key to saving Hogwarts from a new dark threat. The wizarding characters initially doubt the goblin but gradually come to realize their importance and the power of their bond.
Harry Potter himself is often the central character. Since he is the main protagonist in the original series, fanfic writers like to put him in the middle of the goblin debt situations. He has to deal with the consequences and find solutions.
One plot idea could be that the Goblin King has a secret alliance with a dark wizard that Harry and his friends have to uncover. They might find out through a series of mysterious events and clues left in Gringotts. Another could be that the Goblin King decides to rebel against the wizarding world's control over goblin - made artifacts and starts a movement for goblin rights, with Harry caught in the middle as he tries to maintain peace. A third idea is that the Goblin King discovers a powerful ancient magic that could change the balance of power in the wizarding world and Harry has to either stop him from misusing it or convince him to use it for good.
One idea could be that the Head Goblin discovers a long - lost magical artifact hidden deep within the vaults of Gringotts. This artifact has the power to change the balance of magic in the wizarding world. Another could be that the Head Goblin forms an unlikely alliance with Harry Potter to protect Gringotts from a dark wizard who wants to steal all the gold and magical items stored there. Or perhaps the Head Goblin has a secret past related to Harry's family, and this connection unfolds throughout the fanfiction.
Maybe the goblin is an outcast in its own community. Harry befriends it, and they discover a conspiracy within the wizarding world and the goblin banks. As they become friends, they use their combined knowledge of magic and goblin lore to expose the conspiracy. Along the way, Harry learns about the complex history and culture of goblins, which changes his perspective on the magical world.
Maybe the goblins are in danger from a new threat in the wizarding world. They decide to build rockets to escape to a different dimension or planet. Harry Potter discovers their plan and decides to help them. Along the way, they face challenges like magical interference with the rocket's engine (caused by other dark wizards) and they have to use their combined magic to overcome these obstacles. This could be a really exciting and action - packed fanfic plot.
One idea could be Harry Potter arriving in Skyrim and using his magic to combat the dragons. Maybe he teams up with the local mages and they learn from each other's magical techniques.
One idea could be exploring what would happen if a new, mysterious student joined Hogwarts during the Triwizard Tournament. This student could have a hidden agenda related to the Dark Arts and start influencing the events of the tournament in unexpected ways.