Some fanfictions create entirely new goblin characters. For example, there could be a young goblin prodigy who befriends Harry. This character could have extraordinary skills in metal - working magic, which is something goblins are known for in the Potterverse. They might use their skills to create powerful magical items for Harry or help him in his battles.
Griphook is often a popular goblin character in such fanfiction. Since he was already in the original books, he's a familiar face that fanfiction writers can expand on. He might be portrayed as a more heroic figure, helping Harry in ways he didn't in the original story.
There could be an entirely new goblin character created just for this fanfiction. This goblin lawyer could be an outcast from the goblin community because of his more progressive views on wizard - goblin relations. Harry, seeing his potential, hires him to help with his legal battles that require a fresh perspective.
It's hard to say without reading it, but it could be Harry Potter himself. Since it's set in the Harry Potter universe, he might be involved in the goblin - related surprise. Maybe Hermione and Ron could also be part of it, as they are usually by Harry's side in most adventures.
Harry Potter is the obvious main character. The goblin would be another main character. In addition, there could be a wizard or witch who is either helping or hindering Harry and the goblin in their adventures involving the lemon. Maybe it's a teacher from Hogwarts who has some knowledge about the goblin - lemon connection.
Obviously, the Goblin Prince would be one of the main characters. Harry Potter would also be a central figure. There might also be other characters like Hermione and Ron who could get involved in the story, perhaps as they try to understand the motives and actions of the Goblin Prince. And of course, there could be various goblin characters who are part of the Goblin Prince's court or family.
One popular theme is the goblins' relationship with wealth and magic items. Since they are the keepers of Gringotts, many fanfics explore how they manage and protect the treasures. For example, some fanfics might show a goblin's struggle when a valuable item goes missing from the vaults.
In fanfiction, goblins can help in various ways. For example, they might assist Harry Potter with getting access to certain Gringotts vaults that hold crucial items or information. Goblins are known for their skill in handling gold and guarding treasures, so they could use their knowledge to help Harry in his fight against Voldemort by providing him with financial resources or magical artifacts that were previously hidden away.
A common plot twist is that the goblin banker is actually a spy for an underground magical resistance. He has been using his position in Gringotts to gather information. Harry Potter discovers this by accident and has to decide whether to trust him or turn him in. This adds a lot of suspense and moral dilemma to the story.
Obviously, Harry Potter would be one of the main characters. And Griphook, the goblin we know from the books, could also be a main character as he has prior interactions with Harry. Another could be a young, rebellious goblin who wants to change the relationship between goblins and wizards and is the driving force behind the alliance.
Griphook is often an important character. In the original books, he had a significant role in relation to Gringotts, and in fanfiction, he could be the main goblin helping Harry. He might use his knowledge of the bank's secrets and security to protect Harry or lead him to valuable things.