Another plot might involve Harry facing a new kind of dark magic threat at the university. This could be a dark magic that is specific to the academic environment, like a curse on a certain magical textbook that starts spreading chaos among the students. He has to use his skills and knowledge gained at Hogwarts and develop new ones to deal with it.
Well, one interesting plot could be Harry making new and unique friends at the magical university. Maybe he meets a group of students from different magical backgrounds and they form a study group that gets into all sorts of adventures while trying to master new spells.
There might be a new mentor figure, perhaps a wise old professor at the university who takes Harry under his or her wing. This character could help Harry navigate the new and more complex magical education system.
There might be an ancient evil entity that has been trapped within the university grounds for centuries. When Harry arrives, it senses his power and tries to use him to break free. This entity could manipulate other students and staff to achieve its goal, making it a very dangerous and complex antagonist.
Well, one interesting plot could be Harry going to an American wizarding school and comparing it to Hogwarts. Maybe he discovers new magical creatures there that are unique to America.
One possible plot could be Harry being influenced by dark magic artifacts. For example, he might find an ancient cursed object that gradually corrupts his mind and makes him turn dark. Another could be that he is betrayed by those he trusts, which pushes him over the edge into darkness.
One interesting plot could be Harry having to deal with the Slytherin's traditional pure - blood supremacist views while trying to stay true to his own values. He might face challenges from some of his Slytherin housemates who initially look down on him for his 'half - blood' status.
Some fanfictions might have a plot where Harry goes to Azkaban to rescue someone. It could be a friend or a relative who has been wrongly accused. Along the way, he has to navigate the dangerous corridors of Azkaban filled with various traps and curses. He might also meet some old enemies who are also in Azkaban and they try to stop him from achieving his goal. In addition, the magic that keeps Azkaban intact could be a key part of the story, like Harry has to figure out how to manipulate it to his advantage.
One interesting plot could be the sorting of older students into Hogwarts houses when they enter the university. For example, a transfer student from a different magical school might struggle to find their place among the traditional Hogwarts houses. Another plot could involve new magical courses that are only available at the university level, like advanced potion - making for healing purposes. And there might be plots about inter - house relationships that are more complex at the university, as students are older and more independent.
One idea could be Harry making new friends who have no idea about his wizarding past and he has to keep it a secret. Another could be him joining a unique university club related to magic in a very subtle way, like a club for illusionists where he can use some of his real magic skills without being detected.
In some 'Harry Potter Goes Traveling' fanfictions, Harry might travel through time as well as space. He could go back to the time of the founders of Hogwarts to learn the original magic. Or he might visit different historical periods in the wizarding world, like the time of the Great Wizarding War in other countries. This would give him a broader perspective on the history of magic and how different wizarding cultures have dealt with conflict. Also, he could meet his ancestors or relatives from different parts of the world who were wizards and learn about his family's magical heritage.