His best friends, Hermione and Ron, would surely help. Hermione could contribute with her intelligent ideas and knowledge of magic for construction. Ron would be there for the physical labor part, using his strength.
Maybe Harry Potter builds a home in a hidden forest near Hogwarts. He could use magic to create a cozy cottage with a fireplace that always has a warm fire burning, and rooms filled with memories of his friends and adventures.
There might be a fanfiction where Harry decides to build a new home from scratch using magic. He invites all his friends to contribute in their own ways. Hermione might use her vast knowledge of spells to create a library within the home, Ron could help with the more physical aspects using magic, and they all have a great time creating a unique home filled with love and magic.
It could also include some of the Hogwarts professors as main characters. For example, Professor McGonagall, who has always been like a mother figure to Harry. Her wisdom and guidance would be crucial for Harry as he comes home to Hogwarts or the wizarding world in general. And Dumbledore, even if he's passed away, his influence could still be felt strongly throughout the fanfiction.
It could be about creating a new home or a sense of belonging for the characters in the Harry Potter universe. Maybe it focuses on a character who has lost their home and is trying to find a new place to call home within the magical world of Hogwarts or elsewhere in the wizarding realm.
One interesting story could be about Harry's life after Hogwarts in a fanfiction. Maybe he becomes a teacher at Hogwarts and has to deal with a new generation of magical students with their own unique problems.
In this fanfiction, Harry might be greeted by his friends at home. Maybe Hermione and Ron are already there waiting for him with a warm meal and stories to share.
Well, perhaps Harry misses the warmth and safety of the Burrow. He might be on some dangerous adventure away from home and his longing for home gives him the motivation to quickly finish whatever task he's on and return. For example, if he's in a dark forest full of unknown creatures while searching for a powerful magical item for the Order of Phoenix, he'd constantly think about going back to his simple but loving home environment.
One possible theme could be family. Since it's about being closer to home, family relationships, whether good or bad, might be explored. Another theme could be the contrast between the magical world and the normal world at home.