Well, he might start by reforming the House system. Maybe he'd make it more inclusive and less competitive. He could also introduce new classes that focus on practical magic for real - world situations.
Well, when Harry Potter takes over Hogwarts in fanfiction, he'll surely face the challenge of modernizing the curriculum. The magical world is evolving, and the old curriculum might not be sufficient. He also has to handle the different magical families' influence on the school. Some families might want special treatment for their children, which he would need to resist to ensure fairness for all students. And then there's the matter of dealing with any dark magic remnants that might still lurk in the school's corners.
If Harry takes control, he would ensure the safety of all students. He has faced so many threats at Hogwarts, so he'd strengthen the security. He might set up new wards and have more regular patrols. And he'd be very strict about the Forbidden Forest, making sure students don't go there without permission.
His friends like Ron and Hermione would surely support him. They have been through a lot together, and they believe in Harry's leadership. Also, the Weasley family in general would be behind him. They have always been on Harry's side in his battles against the dark forces.
In this fanfiction, it could be that Harry takes over the House of Potter to restore its former glory. He might have to deal with dark forces that have been lurking around the property, and he uses his skills and the help of his friends to cleanse it. Maybe he uncovers a plot against the wizarding world that was somehow connected to his family's house, and he has to prevent it from coming to fruition.
If Harry takes over the Ministry in the fanfiction, he could use his experience to better protect the wizarding world. He has faced Voldemort, so he knows the importance of unity. He would probably encourage more cooperation between different wizarding communities. He could also use his popularity to inspire young wizards and witches to be more involved in making the wizarding world a better place, like starting volunteer programs within the Ministry.
Well, he might start by changing all the unfair rules she had imposed at Hogwarts. He could bring back the fun and freedom in the school, like allowing students to form their own clubs again.
Well, he might use his magic to solve Westeros' political problems. For example, he could use a spell to make the warring factions come to a peaceful negotiation. He might also introduce magic to the people of Westeros, which would completely change their way of life. And his skills in fighting dark forces could be useful in dealing with any threats in Westeros, like the White Walkers.
In such a fanfiction, perhaps Harry Potter could use his magic to bring about major political changes across the world. He might establish a new global wizarding order where magic and Muggle affairs are more intertwined. For example, he could introduce magical solutions to global problems like climate change, using spells to clean the air or water.
There could be some antagonists as well. Maybe some dark wizards who were enemies of the Potter family in the past and are still lurking around the house, trying to stop Harry from taking full control. There might also be some Ministry of Magic officials who are interested in the House of Potter for various reasons, such as the possible presence of powerful magic items. And Neville Longbottom could also be involved, as he was a key figure in the fight against Voldemort and could be there to support Harry in this new adventure.