In many fanfics, Harry Potter might become an Auror after Hogwarts, using his skills to fight dark magic. He could also start a family with Ginny and raise their children in a world that's gradually recovering from the war.
One common plotline is Harry facing new dark threats that emerge after Voldemort's defeat. Another is his relationships with his friends evolving as they enter adulthood. For example, Ron and Hermione might have some marriage - related issues that Harry helps them with.
In the 'harry potter after hogwarts fanfic', a really interesting plot could be about the discovery of new magical creatures or lost spells. Harry, being the adventurous type, might go on quests to explore these new elements. He could also get involved in international wizarding relations, using his fame and experience to bridge gaps between different wizarding communities around the world. This would open up a whole new world of magic for the readers to explore.
Obviously, Harry Potter himself would be a central character. Ron and Hermione, his closest friends, would also likely be in it. Ginny, as Harry's love interest, would probably play a significant role too. Other characters like Neville, who has grown into a strong wizard, could also be featured. And of course, we might see some of the old Hogwarts professors, perhaps McGonagall still guiding the school in some way.
In fanfiction, Harry Potter might become an Auror and fight against the remaining dark forces. He could also start teaching Defence Against the Dark Arts at Hogwarts, passing on his knowledge and skills to the new generations.
He might focus on rebuilding Hogwarts. After all the destruction, it would be a huge task and he could use his influence and skills to bring it back to its former glory.
Often, fanfics show Harry Potter remaining very close to his old friends like Ron and Hermione. They might have regular get - togethers at the Burrow or at their own homes. He would also be part of the wider wizarding community, attending social events and making new friends among the younger generations who look up to him.
Draco Malfoy is often a popular character in these fanfictions. After Hogwarts, he might be trying to redeem himself, or there could be a love story between him and a character like Hermione. His complex past and family history make for interesting storylines. Another popular character could be Neville Longbottom. He has grown so much during his time at Hogwarts, and in fanfiction, he could be a great teacher at Hogwarts, passing on his knowledge of Herbology and his courage to the new students.
In the fanfic, Harry Potter could meet the new generation of students. They would be in awe of him. He might also encounter some of the ghosts, like Nearly Headless Nick, who would surely have some interesting stories to share since Harry left. And there's a good chance he'll meet the caretaker, who would probably give him a hard time about coming back and causing a stir. Moreover, he could cross paths with some of the older students who idolize him and want to learn from his experiences.