Hermione would be a likely companion. She loves learning and exploring, so she'd be eager to go on a traveling adventure with Harry. Ron might also tag along, especially if there's a chance of food and adventure. Neville could be another option. He has grown a lot in courage and his knowledge of plants could come in handy in different magical environments. Luna Lovegood would be a very interesting companion too. Her unique perspective on magic and the world would add a lot of fun and mystery to the journey.
In some fanfictions, Harry could be joined by older characters like Sirius Black (if he were somehow brought back). Sirius has a lot of experience and knowledge of the wizarding world outside of Hogwarts. Remus Lupin could also be a great companion. His calm and wise nature would be useful during travels. Another potential companion could be Dobby. Dobby's loyalty to Harry and his knowledge of the wizarding world from a house - elf's point of view could open up new avenues for exploration. Plus, Dobby could use his magic to help them in tricky situations.
Maybe Neville. He has grown a lot in his magical abilities and his courage. He could bring his knowledge of herbology, which might be useful in different parts of the world. Luna Lovegood could also be a great companion. Her unique perspective on magic would help Harry see things in a different light during his travels.
He could meet an Egyptian wizard who is an expert in ancient magic. This wizard could teach Harry a great deal about the history of magic in Egypt.
Obviously, Harry Potter himself. And there could be characters like Hermione and Ron who might either go with him or be involved in some way from afar. There may also be original characters created for Alfe, such as an Alfe wizard who becomes Harry's guide.
Obviously, Harry Potter himself. Then there could be Hermione and Ron, who might visit him at Harvard or communicate with him via magic. There could also be new characters like his Harvard roommate, who could be a normal Muggle but start to suspect that Harry is not an ordinary guy. And maybe some professors at Harvard who take an interest in Harry's different way of thinking.
In this 'harry potter goes to the sixth world fanfiction', we would expect Harry Potter. Besides him, there might be new wizards or witches native to the sixth world. They could have their own unique powers and personalities. Maybe there are also some half - magical beings that Harry has never encountered before. These new characters would add more complexity and freshness to the story.
Obviously, Harry Potter himself. There could also be some Beautox - natives, like a wizard or witch who is an expert in Beautox magic. Maybe Hermione would somehow find a way to follow Harry and she'd be there too, trying to figure out the new magic system.
He might meet Canadian witches and wizards. There could be a friendly wizard who shows him around the Canadian wizarding community.
He might meet international aurors. These are highly skilled wizards from different countries who are experts in dark wizard catching. They could teach Harry some new combat spells.
He could meet Fleur Delacour's family. Since Fleur is from France, her family might be an important part of the French wizarding community that Harry interacts with.
Harry could meet some local magical creatures that are unique to Africa. For example, there could be a magical creature similar to a hippogriff but with different characteristics. And he may also meet African witches who are experts in herbal magic, which they use to heal and protect their communities. They could teach Harry some of their techniques and knowledge.