Dumbledore could still be around as headmaster, guiding Harry in his new role as a professor. McGonagall would be an important colleague, sharing her wisdom and experience with Harry. There could also be some new characters introduced as professors. For example, a wizard who has studied extensively in the field of time - magic could be teaching a class on that. Or a witch who has traveled the world and is teaching a class on different magical cultures.
Hermione would be a likely colleague. She's highly intelligent and could be teaching a subject like Ancient Runes or Arithmancy. Ron could also be there, perhaps as a flying instructor or teaching something related to magical creatures. Neville might be a Herbology professor, given his love and talent for that subject. Luna could be teaching something really unique, like the study of magical creatures that are often overlooked or misunderstood.
Draco Malfoy could be an interesting colleague. Maybe he has changed over the years and is now teaching a subject like Wizarding Etiquette. Ginny Weasley could be a Quidditch coach, which is like a professor in the field of sports at Hogwarts. And there could be some older students who have graduated and come back to teach, like Oliver Wood coming back to teach advanced Quidditch strategies.
Hermione would be a likely colleague. She's extremely intelligent and could be teaching a subject like Transfiguration or Ancient Runes. She would often share her vast knowledge with Harry and they could collaborate on projects for the students. Another could be Neville. He could be the Herbology professor. Given his own experiences with plants, especially the Venomous Tentacula, he would be great at teaching students how to handle dangerous plants safely.
Hermione would be a likely colleague. Given her thirst for knowledge and academic excellence, she might be teaching a subject like Ancient Runes or Arithmancy. They could often collaborate on projects related to the overall betterment of Hogwarts' curriculum.
In Harry Potter fanfiction, a male professor can play various roles. For example, he could be a mentor figure like Dumbledore, guiding the young wizards. He might also be a villainous professor, creating obstacles for the main characters. Some fanfictions might explore a male professor's backstory, his relationship with other characters in the wizarding world, or his own magical research and discoveries.
Well, in this fanfiction, Harry might be a professor because of his extensive knowledge and experience in magic. He could be teaching younger students and sharing his wisdom.
Hermione would definitely be one of his allies. She is smart and resourceful and would be able to help Harry navigate the new political and magical situations he faces as a prince. For example, she could research ancient laws and prophecies related to his new status.
Voldemort and his Death Eaters would still be the main enemies. But now, Harry's guns would pose a new threat to them. They might not be used to dealing with such Muggle - like weapons, even if they are magically enhanced.
In some fanfictions, it could be an original character created by the author. Maybe a witch who was the result of an affair that his father had before he married his mother. However, this is completely against the canon of the original books, but in the world of fanfiction, anything is possible.
In some fanfictions, it could be Sirius Black. Some fans like to imagine that Sirius had a deeper connection to James Potter's family than just being best friends. They might create a scenario where there was some sort of magic or prophecy involved that made Sirius more than just Harry's godfather, but his actual father in this alternate story line.
Perhaps Hagrid could be his mentor. Hagrid has a lot of knowledge about magical creatures and their parts, which could be useful for Harry in his blacksmithing. He could show Harry how to use things like dragon scales or unicorn hairs in his creations.
One great Naruto and Harry Potter crossover fanfiction could be where Naruto is somehow transported to the wizarding world and meets a Professor Potter. In this kind of story, Naruto might use his ninja skills in Hogwarts, like using his chakra to perform amazing feats that baffle the wizards. He could team up with Professor Potter to fight against dark forces that are threatening both the ninja world and the wizarding world.