It could be a new student at Hogwarts. A young wizard or witch who has always been curious about goblin magic. Maybe they come from a family with a long - standing interest in different magical cultures, so they jump at the chance to train with goblins.
It could also be a character from outside of Hogwarts. A young magical person who has grown up in a different magical community that has closer ties to goblins. They are brought into the Hogwarts - related goblin training to share their knowledge with the Hogwarts students and also to learn more about wizarding magic. This character could bring a fresh perspective to the whole goblin training experience.
Well, it could be about a young wizard or witch who is sent to learn from goblins. Maybe they study the unique magic goblins possess, like their skills in handling precious magical items. The plot might involve the main character facing challenges in understanding the goblin way of life and magic, and eventually using what they've learned to solve a big problem at Hogwarts or in the wizarding world.
Another possibility is that it's a character related to the Veela community. A Veela elder or a young Veela who is chosen for this special training. This character would bring the unique Veela culture and magic into the story, and their interactions with the wizarding world outside of the Veela community would be an interesting aspect of the fanfiction.
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.
It could be some of the pure - blood wizard families who have always looked down on goblins and consider them as inferior beings. They might oppose Harry's attempts to defend the goblin because it goes against their traditional views of the wizard - goblin hierarchy.
It could be a dark wizard who has a vendetta against goblins. This wizard might see goblins as a source of power or wealth and wants to enslave them. So when Harry tries to save the goblin, this dark wizard becomes the main obstacle.
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.
The goblin training could transform Harry into a more street - smart wizard. Goblins have their own set of rules and ways of doing things. Harry would have to adapt to these new ways. This could lead to him being less trusting of traditional wizarding institutions and more likely to question the status quo. His character might become more resourceful as he learns from the goblins' unique skills and knowledge.
The goblin could start off as a mysterious figure. For instance, he could first appear to Harry in a dream, giving him cryptic messages. As the story progresses, we learn that he has his own motives, like seeking revenge on a wizard who wronged him in the past. His character could develop from being a bit of an enigma to a fully - fleshed - out ally with a complex backstory.
It could be Zeus. He is a powerful god and might see Harry as a worthy candidate for training. He could teach Harry about leadership and power control.
Voldemort or his Death Eaters could be antagonists. They might want to raid Gringotts to get powerful magical artifacts or gold to fund their dark deeds. Another option could be a group of corrupt wizards within the Ministry of Magic who see Gringotts as a source of wealth and power that they can control. They could try to undermine the Head Goblin and Harry Potter if they stand in their way.