His best friends Hermione and Ron would surely visit. They might come to help Harry set up new magical experiments or just to relax away from the hustle and bustle of the wizarding world.
Dumbledore, even as a spirit perhaps, could visit to offer Harry some sage advice on how to manage the island and its potential influence on the wider wizarding world. Also, Luna Lovegood might show up, being the curious and free - spirited witch she is, eager to explore the unique flora and fauna of the island. Neville could also visit, bringing with him some rare magical plants to add to the island's collection.
Well, in fanfiction, Neville Longbottom could be one of the visitors. He and Harry could exchange gardening tips as they explore the manor's gardens. Additionally, Dumbledore's portrait might be magically transported to Potter Manor, and he could offer his wisdom and guidance to Harry as he lives in the manor. And of course, Hagrid might come with some magical creatures to show Harry, adding more excitement to the manor.
Hermione would surely visit. She'd be there with a stack of books, ready to help Harry catch up on his studies while he recovers. And Ron would be right beside her, probably with some treats from the Hogwarts kitchen.
There could be some of the house - elves that Harry has freed. They might choose to live on the island, using their magic to help with various tasks such as farming magical plants or taking care of the island's infrastructure. Also, some of the students from Hogwarts who were inspired by Harry could be there. They might be learning new forms of magic that are specific to the island or studying the unique magical ecosystem there.
His best friends, Ron and Hermione, would most likely visit him. They have always been by his side through thick and thin, so they would find a way to get to the tent to check on him, bring him supplies, and offer their support.
Ron might be there too. He could use his skills in handling magical creatures to populate the island with friendly ones. And he could also help with fishing in the surrounding waters using magic, providing food for those on the island.
Perhaps Hagrid could assist. He has a deep understanding of magical creatures and could help Harry populate the island with them. He might also use his strength to help with the physical construction, like moving large rocks or trees.
Dumbledore, if he were still alive in the fanfiction, could offer his wisdom. He might guide Harry on the moral and magical implications of creating an island. He could also provide some powerful spells or artifacts that would aid in the construction process.
Some pure - blood supremacist wizards could be antagonists. They don't like the idea of Harry creating a haven for all kinds of wizards on the island. They might try to sabotage the island's creation or attack it once it's made, fearing that it will disrupt the 'purity' of the wizarding bloodlines.
The Nine - Tails could be considered as a 'visitor' in a way. Since Naruto is in seclusion, he has more time to interact with the Nine - Tails inside him. Also, it's possible that some of the spirits of the past Hokages might visit Naruto. They have a connection to Naruto, and they might want to guide him during this important time of self - improvement. They could share their experiences and knowledge to help Naruto become a better shinobi.
Perhaps he uses the island as a secret training ground. He could practice advanced spells away from the prying eyes of Hogwarts faculty and students. Harry might also build his own magical fortress on the island for protection and privacy.