Hermione might also come across some magical creatures that are guarding certain vaults in Gringotts. For example, a dragon that she has to find a way to bypass without getting burned. These encounters would add more excitement and danger to her visit to the wizarding bank.
There's a chance she meets some old Death Eaters who are lurking around Spinners End. This would put her in a very dangerous situation, but it would also make for an exciting plot. She would have to use her wits and magic skills to outsmart them. Or perhaps she meets some of Snape's old school friends who can provide insights into his character and motives.
She could meet Bella Swan. They might start off as a bit of an odd couple, with Bella's more reserved nature compared to Hermione's boldness. But they could learn a lot from each other.
There might be Muggle soldiers who are initially skeptical of Hermione but later become her allies. She could also meet some higher - up military officials who either support or oppose her presence in the army. For instance, a general who sees the potential in Hermione's magical abilities and wants to utilize them for the greater good, or a colonel who is against having a witch in the military due to traditional beliefs.
In this fanfiction, Hermione could be on a mission to retrieve a valuable item from Gringotts. It might be an heirloom of her family that was wrongfully taken and stored there. Along the way, she has to face many challenges like dealing with the goblins' tricky rules and overcoming some magical traps. She may also meet some unexpected allies or enemies within the vaults of Gringotts.
She could meet the headmistress of St Trinians. That would be an interesting encounter as Hermione tries to understand the school's rules and the headmistress tries to figure out this strange, book - smart girl. Also, she might meet the troublemakers of the school, those girls who are always getting into scrapes and might see Hermione as either a threat or someone to rope into their schemes.
Perhaps she'll meet older, more experienced students who can act as mentors. These students could introduce her to secrets of the new school that are not easily accessible to newcomers. They might also help her with any homesickness she has for Hogwarts.
Often, the goblins can be antagonists. If they have their own motives that conflict with Harry and Hermione's, like protecting a dark secret in the vaults or trying to take advantage of the situation for their own gain. Another possible antagonist could be a Death Eater who has infiltrated Gringotts to either steal something important or to ambush Harry and Hermione.
They could meet American wizards who have a very different style of magic. Maybe some of the native American wizards who have their own ancient magical traditions. These wizards could teach Harry and Hermione about magic that is connected to nature in ways they've never seen before in Britain.
She might meet her old teachers. They would be surprised to see how much she's grown and changed. And of course, her former classmates. There could be the popular girl from school who is now a bit jealous of Hermione's confidence. Or the nerdy boy who has now become a successful scientist and they can have an interesting exchange about different kinds of knowledge, magical and Muggle.
In some fanfictions, Harry might meet a goblin with a special mission for him. This goblin could be an outcast among his kind and believes that Harry is the only one who can help. So, he takes Harry on a journey through the deepest parts of Gringotts, where Harry gets to see parts of the bank that no one else has ever seen. During this journey, Harry also meets other strange and interesting characters that are somehow connected to the goblin's mission.